BU Motors and Generators training. Start here menu. BU Motors and Generators April 18, 2011 Slide 1

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1 BU Motors and Generators training Start here menu April 18, 2011 Slide 1 1

2 Dear Student, Welcome to Technical introduction to motors and generators e-learning course program! K115e K110e K116e K111e K117e K112e K118e K113e K114e Database needed: ABB Library, (for ABB personnel only) Inside web pages, (for ABB personnel only) External web pages: Course administration: BU Motors and generators training Questions and discussions Technical assistance April 18, 2011 Slide 2 Welcome to the Technical introduction to motors and generators e-learning course program! This course program has been developed as an introduction to our products for new sales person in BU Motors and generators. It leads you to the basic electrical and mechanical structure of our motors and explains the technical details of the different types of motors and generators. To study the courses, you will need access to ABB Library, ABB Inside and our external web pages. Course consist of courses from K110e to K118e. Even though this course is on the Internet and you can study alone where and whenever your want, please be active and ask questions. Our training team will assist you in this training, please send an to motorsandgenerators.training@fi.abb.com 2

3 Course description Course duration Course type Prerequisites and Recommendations Main topics: Basics of electrical motors and standards DC Motors HV Motors LV Motors Motors for explosive atmospheres Servomotors Synchronous motors and generators Generators for wind turbine applications Permanent magnet motors April 18, 2011 Slide 3 These are a web-based training courses, which are designed to be studied according to your individual plan, usually within five weeks. The duration of the course depends on the participant. Each course is equivalent to 0,5 days classroom training. The language of the course is English. A basic knowledge and experience with using PCs and the Windows environment is recommended before attending the course. It is assumed users are new to e-learning software and methods. Course program K100e-K105e is recommended before studying Technical introduction to motors and generators course program. Main topics are: Basics of electrical motors and standards DC Motors HV Motors LV Motors Motors for explosive atmospheres Servomotors Synchronous motors and generators Generators for wind turbine applications Permanent magnet motors 3

4 Course material Access to course material / See Notes page-text and attachments Course material Final exam Course evaluation / feedback form Turn on the volume to hear the recorded material April 18, 2011 Slide 4 Choose Notes to see the whole course material. To exit from the unit, click Exit in the upper, right corner and Exit now. If you want to take a break in your studies, you can continue afterwards from were you left off by choosing Review and yes to resume your presentation. Once you start studying and open a unit, the status of this unit changes from Not Attempted to Incomplete. The status changes from Incomplete into Complete when you have studied all the material. The Student binder for this course can be found from the course in the Attachments. In connection to this course there is a final exam. 50% of the questions have to be answered correctly to pass the course. Remember to turn on the volume if you want to hear the recorded material Please remember to fill in the course evaluation form. We highly appreciate your feedback since it helps us to improve the quality of the course. The information you give is treated in strict confidence. 4

5 Learning paths Learning paths for motors and generators: d9.aspx Course K110e is mandatory for all technical sales persons in BU Motors and Generators Please look up a terminology in TermBank April 18, 2011 Slide 5 New employees in our motors sales have different educational backgrounds and work experience. Learning paths have been designed to help you to choose the correct courses for your individual needs. This course program has been developed as an introduction to our products for new sales person in BU Motors and Generators. We recommend to start your studies with K110e Basics of electrical motors and standards e-learning course which is a mandatory course for all sales people. It leads you to the basic electrical and mechanical structure of our motors and explains the technical details of the different types of motors and generators. After completing this first course, you may continue with other courses within this course program starting from K111e to K118e. You are recommended to select the courses you deal with in your job area. During your studies, you can look up a terminology through the Termbank linked in ABB Intranet. 5

6 Learning paths Technical introduction E-learning courses K110e K111e Seminars G977 G978 G951e1_2 K112e K113e G954/G982 G952/G953/G982 K114e K115e Course program G951e Technical introduction has been replaced by course program K110e K118e. K116e K117e K118e BU ABB Motors BU Motors and Generators and Generators April 18, 2011 Slide 6 BU Motors and Generators training offers technical introduction for motors and generators e-learning course program: K110e-K118e (former G951e1_2-G951e10). You may still find some of these courses with the old code G951e. For more information about our learning paths, please see our web pages. Code explanations: K110e Basics of electrical motors and standards (G951e1_2) K111e DC Motors (G951e3) K112e High voltage motors (G951e4) K113e Low voltage motors (G951e5) K114e Motors and Generators for explosive atmospheres (G951e6) K115e Servomotors (G951e7) K116e Synchronous motors and generators (G951e8) K117e Generators for wind turbine applications (G951e9) K118e Permanent magnet motors (G951e10) Former G951e Course program (G951e1_2 G951e10) equals to courses K110e K118e G977 DC Motor sales tool training G978 DC Motor hands-on training G953 LV Motor training G952 LV Motor technical training G954 HV Motors and generators technical training 6

7 Reference material Reference materials to Motors: Motor Guide Low voltage Process performance motors Low voltage Industrial performance motors Low voltage General performance motors High voltage induction motors technical catalogue High voltage induction motors for Chemical, Oil and Gas EN Motors for explosive atmospheres DMI Catalogue April 18, 2011 Slide 7 During the courses you will need to refer to ABB s internal or external web sites. Here you can also find links to catalogues which you can use during the course. 7

8 Introduction to Motors and Generators For information on our training events, please see: cede.aspx K110e K118e, produced for ABB, BU Motors and Generators, First Edition (v.1.0) Contact information: BU Motors and Generators training P.O.Box 633, FIN Vaasa, Finland Tel Fax April 18, 2011 Slide 8 For information on our training events, visit us at motors and generators training web site. The course program has been produced for ABB Business Unit Motors and Generators in This is the first edition, version 1.0, copyright 2011 by ABB, BU Motors and Generators All rights reserved. No part of this document may be reproduced or copied without permission of ABB, BU Motors and Generators Good luck and have fun in learning! 8

9 April 18, 2011 Slide 9 9

10 K110e Unit 1 Basics of electrical motors and generators April 18, 2011 Slide 10 10

11 Objectives After completing this course module you will understand: the basics of the electrical motor the structure and demands of a motor the physical background of the induction motor the electrical structure of ABB's low and high voltage induction motors and generators April 18, 2011 Slide 11 After successfully completing this course module you will be able to describe the basics of the electrical motors and understand the structure and demands of a motor. This module will also explain the physical background of the induction motor and the electrical structure of ABB's low and high voltage induction motors and generators, including the electrical motor components, torque and speed, power factor, efficiency, rating plate, winding, and insulation. 11

12 Electrical motor More than half of the electrical energy produced is used by electrical motors Electrical motors are used worldwide in many industrial, utility, commercial, or residential applications April 18, 2011 Slide 12 Electricity is an important source of energy in our society. More than half of the electrical energy produced is used by electrical motors. Electrical motors are used worldwide in many industrial, utility, commercial, or residential applications. 12

13 Principles of action of electrical motors and generators Used to convert mechanical power into electrical energy or vice versa All rely on electromagnetic induction April 18, 2011 Slide 13 Rotating electrical machines are used to convert mechanical power into electrical energy or vice versa. All electrical machines, whether motors or generators using direct or alternating current, rely on the principles of electromagnetic induction for their action. 13

14 Principles of action of electrical motors and generators A conductor moving across a magnetic field creates an electromotive force (emf) Resulting current flow and magnetic field around the conductor tend to oppose the motion that is producing the emf April 18, 2011 Slide 14 A conductor moving across a magnetic field becomes the seat of an electromotive force (emf). The direction of the emf is in the right angle to both the direction of the motion and the direction of the magnetic field. The amount of "induced voltage depends upon the length of the conductor actually in the field, the speed of the relative motion between the conductor and the magnetic field, and the strength of the magnetic field. Because of the direction or polarity of the induced emf, the resulting current flow and the magnetic field around the conductor produced by it tend to oppose the motion that is producing the emf. The principle of this action can be presented in best for instance, an elementary generator consisting of a loop of wire that is mechanically rotated within a magnetic field. 14

15 Principles of action of electrical motors and generators single-phase machine delta connection April 18, 2011 Slide 15 In the illustration, A will always be moving in the opposite direction of B, relative to the magnetic field, and hence emf induced in A will be in the opposite direction to that of B. These two emfs, therefore, add up when the coil sides are connected as shown. When the coil side A is in position 1, it will be moving parallel to the direction of the magnetic field. There is no relative motion across the field and no emf is induced. When the coil has rotated 90 to position 2, it will be moving at right angles to the field and an emf is induced towards the observer s direction, as shown by the arrows. Slip ring R1 will, therefore, appear to have positive polarity with regard to R2. After a further 90 rotation, coil side A will again be moving parallel to the direction of the field and no emf will be induced. After a 270 rotation, in position 4, the coil side will again be moving at right angles to the field and an emf will be induced in the opposite direction to that of position 2 since the direction of movement is now reversed. Slip ring R1 will now appear to have negative polarity with regard to R2. This elementary generator produces an emf that is alternating in direction with a complete cycle of positive and negative changes taking place once per revolution. Since it is relative motion between conductor and field, which includes the emf, it matters little whether the conductor is moving in a stationary field system or whether the field system is moving within stationary conductors. The alternator described in this example is known as a single-phase machine because there is only one circuit where the emf is induced. It is possible to install 3 separate groups. Now the stator has three separate groups of coils spaced 120 electrical degrees apart round the stator core. The voltages in each of these "phases" reach maximum values at different times as the magnetic field passes them in succession. The voltage, which appears between any of the 3 machine terminals, is that of two-phase windings in series. Since these are 120 out of phase, the terminal voltage is 1.73 times that of the voltage of one phase. Alternatively, the end of one coil group can be connected to the start of another to form a closed loop, the joints forming the terminal connections. This is known as the delta connection. The terminal voltage is the same as that of each phase and the line current is shared between the phase windings. 15

16 Principles of action of electrical motors and generators Video: rotation Created by: Roger Busque Ingeniero Industrial & Master Project Manager por La Salle. Industrial Engineer & Master Project Manager by La Salle April 18, 2011 Slide 16 Here is a video clip showing the rotation phase described in the previous page. 16

17 Principles of action of electrical motors and generators To understand the basics, see: Faraday's law Fleming's left hand rule April 18, 2011 Slide 17 The illustration shows voltage in three phases of a three-phase alternator. To understand the basics more deeply, take a look at the following web pages: About Faraday's law: and About Fleming's left hand rule: It is not necessary to memorize the formulas, instead, try to understand the idea behind the theory. 17

18 Electrical motor components Active parts of an HV motor Stator Bearing Rotor Bearing April 18, 2011 Slide 18 Here a high voltage motor/generator is illustrated. The basic construction of the AC induction motor is simple and has changed very little over the years. Next, we will discuss the basic components of a motor. The stator windings are insulated copper wire, which are inserted into slots in the stator laminations. These slots have insulation between the windings and the steel laminations. This is called the "stator core". The different winding designs provide different output and speed combinations. The stator core is inserted into the stator frame. The ends of the winding are brought out through the motor casing to the terminal board in a terminal box mounted on the frame. This is where the mains leads are connected. The rotor consists of laminations, the shaft, and the rotor winding or bars. The type of winding will depend on the type of motor required. If the rotor has a winding similar to that of the stator, it is known as a "wound rotor motor" (also known as a slip-ring motor). If the "winding" consists of solid bars that are joined at either end by a short-circuit ring, it is known as a "squirrel cage" motor. This is because the cage of the rotor resembles the cage that squirrels play with when in captivity. The bars are generally aluminum, but can be copper or any such material. Aluminum is commonly used for LV induction motors and copper for HV motors and generators. The squirrel cage rotor motor is the most common type in use today as it requires simple control gear and, in most cases, can be used instead of a wound rotor motor. The stator core and rotor core constitute the active part of a motor. The bearings are used to support the shaft and to enable it to rotate. 18

19 Electrical motor components Active parts of an HV motor Video: the rotor packet Created by: Roger Busque April 18, 2011 Slide 19 Here is a video clip showing the stator packet and rotor packet, which constitute the active part of a motor. 19

20 Electrical motor components Active parts of a LV motor Bearing Stator Rotor Bearing April 18, 2011 Slide 20 The illustration shows an example of a low voltage motor. The main difference between a low voltage motor and a high voltage motor is the stator winding. The LV Motor is random-wounded, the HV Motor is formwounded. 20

21 Electrical motor components Active parts of a LV motor Video: rotor Created by: Roger Busque April 18, 2011 Slide 21 The rotor consists of laminations, the shaft, and the rotor winding or bars. 21

22 Voltage of a LV/HV motor and generator Motors: Low voltage 0 < U 1 kv Medium voltage 1 < U 6.6 kv High voltage 6.6 < U 11.5 kv Generator: Low Voltage: 0 1kV Medium Voltage: 1kV 15 kv April 18, 2011 Slide 22 Internally, sometimes the terms 'medium voltage' and 'high voltage' motors/generators can be used. It is good to know the difference between them. 22

23 Components of a HV motor/generator BU ABB Motors BU Motors and Generators and Generators April 18, 2011 Slide 23 The illustration shows an explosion view of a high voltage motor/generator (AMA). 23

24 Components of a LV motor Terminal box lid Terminal block D-end Bearing Terminal box Bearing Fan cover Fan N-end Shaft Frame Rotor Stator core & stator winding April 18, 2011 Slide 24 The illustration shows the main components of a low voltage motor. The active parts of the motor are: rotor, stator core, and stator winding. 24

25 Magnetism The illustration shows the equivalence between a permanent magnet and a current. April 18, 2011 Slide 25 A magnetic flux is created by the presence of magnetic poles, for example the north and south poles of a magnet. Flux is a term for the magnetic flow from the north to the south pole. The illustration shows the equivalence between a permanent magnet and a current. 25

26 Magnetism Video: Magnetic flux 1 Created by: Roger Busque Video: Magnetic flux 2 Created by: Roger Busque April 18, 2011 Slide 26 Video clips of Magnetic flux 1 and 2. 26

27 Magnetic field in a motor FLUX Stator core Stator winding Rotor packet Rotor bar Air gap between stator and rotor April 18, 2011 Slide 27 When a three-phase AC voltage supply is connected to the stator windings, a rotating magnetic field is formed. This results a magnetic flux in the air gap where the torque of the motor is produced. The rotating magnetic fields produced by the stator induce a current into the conductive loops of the rotor. The rotor has conductive bars, which are short-circuited to form conductive closed loops. The resulting form is similar to a squirrel cage. Once that occurs, the magnetic field causes forces to act on the current-carrying conductors, which results in a torque on the rotor. 27

28 Pole number The pole number is the number of magnetizing poles generated by the stator winding April 18, 2011 Slide 28 The pole number is the number of magnetizing poles generated by the stator winding. Poles exist in pairs, north and south poles, by the direction of the magnetic field, so the pole number is always an even number. One north pole (N) and one south pole (S) form one pole pair (p), and they follow each other. Stator winding produces a rotating magnetic field when supplied with a three-phase AC system. 28

29 Magnetic field in a motor April 18, 2011 Slide 29 The speed of the magnetic field rotating under a certain supply frequency depends on the pole number of the winding. Windings with different pole numbers differ from each other with regard to coil shape and location in the stator slots. Rotational speed of the magnetic field dependent on the winding pole number at 50 Hz supply frequency in the following way: 2-pole (2p=2) winding produces 3,000 rpm speed; 4-pole (2p=4) winding produces 1,500 rpm speed; 6-pole (2p=6) winding produces 1,000 rpm speed; and 8-pole (2p=8) winding produces 750 rpm speed. At 60 Hz supply frequency the speed values are 20 % higher. The abbreviation p stands for pole pair number and the abbreviation 2p means pole number. 29

30 Windings Windings designed for a specific voltage and frequency Slot windings used as stator windings rotor windings in the induction motors/generators April 18, 2011 Slide 30 The windings are designed for a given voltage and frequency. Slot windings are used as stator windings and also as rotor windings in the induction motors/generators. 30

31 Stator winding Random winding Form wound winding April 18, 2011 Slide 31 Windings in a motor provide a path for the AC current to flow along, which, in turn, produces the rotating magnetic field that causes the rotor to rotate. Winding is done by putting conductive copper into the stator slots so that the current flowing in the copper generates a rotating magnetic field in the air gap between the stator and the rotor. This magnetic field grabs the rotor bars and forces the rotor to rotate along with the magnetic field. In one slot there can be up to 150 turns of copper in random wound winding and up to 50 in form wound winding. There are two basic stator winding styles: random winding and form wound winding. In random winding the copper used in the winding is in the form of wire and in any one slot the turns are more or less in random order. There are many different ways of doing random winding - some are more suitable for machine winding, others have superior mechanical strength or desirable effects on efficiency. Random winding is the winding style used for most low voltage motors. In form wound winding rectangular copper wires are used instead of round wires. Form wound winding is used when high voltage motors and generators are wound. The stator winding design of the HV motors and generators combines the class F insulation system with vacuum pressure impregnation (VPI). This method has been used since 1977 and is well known for its high reliability. While the insulation meets the requirements of the thermal class F (temperature limit 155oC), the motors are normally rated to class B, which gives a good overload margin and provides a long life. The basic impulse level exceeds IEC requirements. The windings are designed to cope with the highest mechanical stresses, including the effects of rapid auto-reclosure in phase opposition. 31

32 Poles Winding Diagram Single layer 2p = 4 poles Q1 = 72 slots q1 = 6 slots (for every pole of every phase) W = 15 teeth (between entrance and exit of one turn) April 18, 2011 Slide 32 The diagram is a tool for transferring information between the designer and manufacturing. For different pole numbers there are different winding diagrams to indicate the order of the wires. In a winding diagram every phase is marked with a different color. 32

33 Insulation Insulation systems are dimensioned according to: voltage level Supply voltage type environmental conditions Endurance tests when new insulation systems are developed: electrical aging thermal aging mechanical aging aging due to surrounding conditions combined aging April 18, 2011 Slide 33 Insulation systems are dimensioned according to several factors: voltage level, supply voltage type (DOL = Direct On Line, PWM-converter, cycloconverter), environmental conditions, for example, height of the site above sea level, temperature, and humidity. Endurance tests are needed when new insulation systems are developed. Typical endurance tests are electrical aging, thermal aging, mechanical aging (for example vibration), aging due to surrounding conditions, and combined aging (for example, thermal and electrical). Aging tests are typically very long lasting, even years. To reduce the time, they are normally done as so-called accelerated tests with higher stresses (for example, voltage and frequency and temperature) than in real operation. The life-times corresponding to the stresses in real operation can be calculated from these results. When developing insulation systems, the manufacturing point of view also has to be taken into account, in other words, how to manufacture reliably and economically without occupational safety problems. 33

34 DC motors winding and insulation Windings designed for a specific voltage Coils used as stator windings Slot windings used as rotor windings April 18, 2011 Slide 34 The windings are designed for a given voltage. Coils are used as stator windings, and slot windings are used as rotor windings in these motors or generators. 34

35 DC Motor stator winding The main tasks of the DC motor stator: produce a fixed magnetic flux to interact with the armature house the commutating windings and compensation windings Main components of the stator: frame of laminated electroplates main poles and interpoles of laminated electroplates, stator windings and commutation windings of varnish-insulated copper wire compensation windings (not DMI ) April 18, 2011 Slide 35 The windings in the motor provide a path for the DC current to flow along, which, in turn, produces the rotating magnetic field that causes the rotor to rotate. The main task of the DC motor stator is to produce a fixed magnetic flux to interact with the armature. This is done by the excitation winding. The stator also houses the commutating windings and compensation windings, which are auxiliary devices that are used to prevent deformation of the main flux. A compensation winding is installed on the magnetic poles of the stator to smoothen the field across the pole. Without the compensation winding the left side of the N-pole would get saturated because of the additional magnetic field. Commutating windings or interpoles are installed between the magnetic poles to straighten the magnetic field. Because of armature reaction, the magnetic field bends and causes misplacement in the inducted voltage at the armature winding. The main components of the stator are: frame of laminated electroplates; main poles and interpoles of laminated electroplates; stator windings and commutation windings of varnish-insulated copper wire; and compensation windings (not DMI ). 35

36 DC 6 Poles winding diagram April 18, 2011 Slide 36 The winding diagram indicates the order of the wires, as shown in this diagram for 6 poles. 36

37 DC Insulation Insulation system: moisture-resistant suitable for use in tropical climates without modification Armature coils and stator windings have dual insulation coats Copper wire insulation, the Nomex and the impregnation varnish have a temperature index above class H April 18, 2011 Slide 37 The motors comply with the requirements of Class 200 /H insulation. The insulation system is moistureresistant and is suitable for use in tropical climates without modification. The armature coils and stator windings have dual insulation coats. The base coat is a polyesterimide with a top coat of polyamide-imide enamel. The insulation to earth is of amid fiber (Nomex). All windings are impregnated with varnish, which gives high mechanical strength. The copper wire insulation, the Nomex and the impregnation varnish have a temperature index well above class H. There is, therefore, a high margin of safety in addition to the high overload capacity. 37

38 April 18, 2011 Slide 38 38

39 K110e Unit 2 Torque, speed and formulas April 18, 2011 Slide 39 39

40 Torque and speed of an AC motor locked-rotor torque pull-up torque breakdown torque April 18, 2011 Slide 40 An asynchronous motor is a motor whose rotor does not rotate at exactly the same speed as the stator field. The locked-rotor torque is the minimum measured torque the motor develops at its shaft extension with the rotor stationary and the rated voltage and frequency applied. The pull-up torque is the smallest torque the motor develops between zero speed and the speed corresponding to the breakdown torque when the motor is supplied with the rated voltage and frequency. This definition does not apply to induction motors, whose torque continuously decreases with increasing speed. This value applies to the usual mean torque characteristic, which excludes transient effects. The breakdown torque is the maximum torque the motor develops with the rated voltage and frequency applied at the operating temperature and when constantly loaded. This term does not apply to motors whose torque steadily decreases with increasing speed. They do not have definite breakdown torque. If the rotor is mechanically driven by an external machine at a speed that is greater than that of the rotating magnetic field, with the machine connected to the power network and the direction of rotation the same as that of the stator field, the asynchronous machine becomes an asynchronous generator. The asynchronous generator returns the power applied mechanically to its rotor as electric power to the network, in this case over-synchronously because the slip is negative. The rotor currents are reversed and the torque produced opposes the rotation of the machine, that is, it tends to retard it. 40

41 AC Speed - magnetic field n s [ RPM] = f [ Hz] 120 pole number The synchronous speed can be calculated with the formulas April 18, 2011 Slide 41 The speed of the rotating field is constant and it rotates at synchronous speed. The synchronous speed is dependent on the frequency and the pole number of the winding. The synchronous speed can be calculated with the formula shown in this slide. The synchronous speed of the motor is determined by the frequency of the supply voltage and the pole number of the motor. f in the formula stands for Electrical frequency in Hz (50Hz or 60 Hz). 41

42 AC Voltage versus time April 18, 2011 Slide 42 An AC Voltage is defined by the value of volts and the frequency. p = Number of pole pairs (=number of poles / 2). The flux is rotated at a speed called "synchronous speed", corresponding to the electrical frequency of the network and to the number of pole pairs. As long as the rotor is rotated at synchronous speed, no current is induced in the rotor bar, and consequently no torque is developed by the motor. Current only exists in the rotor bar if the speed of the rotor (n) is below the synchronous speed (as soon as a load torque is applied to the shaft), which means that the speed of the rotor does not rotate at synchronous speed, and the rotor speed lags behind the speed of the magnetic field. In a case of generating, the speed of the rotor is above the synchronous speed. 42

43 AC Torque curve April 18, 2011 Slide 43 The difference between the rotating speed of the flux and the rotating speed of the rotor is called the slip of an asynchronous motor (the opposite of synchronous machines, where no slip exists, even in the presence of load torque). 43

44 Slip Slip [ RPM] = ns n e.g rmp 992rpm The slip can be expressed in either rpm or per unit n = nominal speed ns = synchronous speed Slip [%] = ns n n s e.g rmp 992rpm 1000 rmp April 18, 2011 Slide 44 The slip can be expressed in either rpm or per unit, as is shown in the formulas. n stands for nominal speed and ns stands for synchronous speed. 44

45 Torque v.s. speed for Asynchronous motor April 18, 2011 Slide 45 The illustration shows the effect of increased speed on torque for an asynchronous motor. The magnitude of the (mechanical) torque available at the shaft depends on the magnitude of the slip that is, on the amount the rotor speed lags behind the speed of the rotating magnetic field. The relationship between the torque and the speed of the motor is illustrated by the speed-torque characteristic. 45

46 Torque v.s. speed for Synchronous motor April 18, 2011 Slide 46 The illustration shows the effect of increased speed on torque for a synchronous motor. 46

47 Torque An increase in power increases the torque, whereas an increase in speed decreases the torque T = Torque (Nm) P = Output power (kw) n = Speed (r/min) April 18, 2011 Slide 47 Torque is generated when the magnetic field of the stator winding forces the rotor bars to turn around the centre of the axis shaft. From the equation one can see that an increase in power increases the torque, whereas an increase in speed decreases the torque. These three features are bound by the fact that T * n / P is always In the equation: T = Torque (Nm); P = Output power (kw); and n = Speed (r/min). When calculating torque, it is important to take into account: the starting torque; the maximum torque; the starting current; and the minimum torque. 47

48 Torque April 18, 2011 Slide 48 This graph is typical for an LV motor. It shows the Torque/speed curve. The shape of the torque/speed curve is determined by the slot shapes and slot alignment in the stator and rotor. The level of the Nominal torque is determined by the winding (number of turns). According to IEC, the maximum torque (Tmax) of the motor should always be more than 1.6 times the nominal torque (Tn). At a speed of 0 rpm the motor can give starting torque (Ts). This Ts should be big enough to counter the decelerating masses of the load and rotating rotor body in less than the given maximum permitted starting time. 48

49 Torque April 18, 2011 Slide 49 This graph is typical for an MV or large motor. The minimum torque (Tmin) is not always at 0 rpm, for example a double cage rotor has minimum torque at around 0.7 times the nominal speed. This should be taken into account when dimensioning motors for constant torque applications. At direct-on-line start the torque produced by the motor has to be greater than the load torque (with reasonable gap) at any speed. If the load torque at any speed is greater than the torque created by the motor, the motor will not be able to start or achieve nominal speed. 49

50 Torque April 18, 2011 Slide 50 The starting current of large motors may cause voltage dips, especially in weak grids. Therefore, motors have to be able to start with reasonable under voltage. 50

51 Torque April 18, 2011 Slide 51 51

52 Torque April 18, 2011 Slide 52 A high current is generated when an asynchronous motor is switched on. The starting current depends on the motor design; the value is usually between 6.5 and 7.5 times the nominal current and the shape is determined by the same parameters as the torque design. The illustration shows the "shape" of torque and current versus speed for small motors. 52

53 Torque April 18, 2011 Slide 53 The illustration shows the "shape" of torque and current versus speed for large motors. 53

54 Formulas P(kW) = T(Nm) x w(rd/s) / 1000 ω(rd/s) = 2pn / 60 (where n is rpm) P(kW) = T(Nm) x n x 2p / or P(kW) T(Nm) = [ 2π ] [ ] x n P(kW) [ ] [ ] x n T(Nm) = April 18, 2011 Slide 54 Torque is the rotational equivalent of linear force and, for any rotating machine, if Power and Speed are known, the Torque is given by the formula shown in the blue background. In the formula: T = Torque (Nm), P= Output power (kw), and n= Speed (r/min). In the formula, 9550 is a constant, which can be calculated with the either of the formulas shown on the right. 54

55 Operation U d I A E I f DC Motor Φ Toutput= k φ IA φ= f() If TAcc = Toutput T ( ) = Ud E IA Ri E= k n φ Ud = E+ = Ud Ri IA n k φ ( Ri IA) ( ) load April 18, 2011 Slide 55 (1) The output torque of the motor is proportional to the armature current as long as (2)the excitation is kept constant. (3) If the output torque exceeds the load torque, there is acceleration torque and the speed of the motor starts to increase. (4) The armature current and, accordingly, the output torque can be increased by increasing the voltage supplied by the DC converter. (5) When the armature starts to rotate through the magnetic flux of the stator, a voltage (emf) is induced, the polarity of which is the opposite of the supply voltage. (6) To maintain the current (and torque), the supply voltage has to be increased as the speed and armature emf increase. The speed can be controlled by the supply voltage until the nominal armature voltage has been reached. (7) This normally coincides with reaching the maximum output voltage of the supplying DC converter. The speed range from standstill up to this point is called the basic speed range. To increase the speed above the basic speed range, the armature emf has to be decreased. As we have seen (5), the armature emf depends on excitation as well as speed. The speed can be further increased by decreasing the excitation (7). However, since torque is a direct function of excitation (2), from this point on the available torque decreases in inverse proportion to the speed. This speed range is called the field weakening speed range. For motors without compensation windings the relationship between basic and field weakening speed range is 1:3, and for compensated motors 1:5. The ultimate speed limit of a DC motor is set by mechanical parameters. 55

56 Controlling torque and speed by excitation Armature Voltage U N U A Armature Current I A I N Excitation Current I N I f Torque T N T April 18, 2011 Slide 56 Power P N P Basic Speed nb Field n max Weakening Speed n As is evident from equations 1 and 2, it is also possible to control the magnitude and direction of the torque entirely by varying the field current. Nevertheless, this is rarely done in modern drives, because the excitation winding has a much higher impedance than the armature, which makes torque by this method slower. 56

57 DMI Motor characteristics Torque as a function of speed 1,2 Torque 1 Constant Torque (P=k x n) 0,8 Constant Power (P=k) Torque (Nm) 0,6 0,4 0,2 Basic Field Weakening Commutation limit (P=k/n) Commutation Limit (compensation winding) Mechanical Limit Speed [rpm] April 18, 2011 Slide 57 This graph demonstrates the relationship between torque and rotational speed (RPM). Maximum torque is generated when the rotor is stationary and to a very low speed. In the range for Constant power, torque drops off sharply, while the power generated is at a maximum. The commutation limit is where both torque and power fall due to limitation of current flow by the resistance of commutator brushes and the maximum voltage that can be applied across each winding. The mechanical limit is the maximum safe speed of the rotor. 57

58 DMI Motor characteristics Power as a function of speed Power 1,2 1 Constant Torque (P=k x n) Power (kw) 0,8 0,6 0,4 0,2 Basic Field Weakening Speed Range Constant Power (P=k) Commutation Limit (P=k/n) Commutation Limit (compensation winding) Mechanical Limit Speed [rpm] April 18, 2011 Slide 58 This graph demonstrates the relationship between power and rotational speed (RPM). Maximum torque is generated when the rotor is at an optimum speed. In the Constant Torque range, power developed rises sharply until it reaches its maximum. This maximum power output is maintained across a range of rotation speed. Again, the limitations of the commutator design for DC motors is shown by the fall of the power generated even as the motor speed increases. 58

59 Speed trimming Armature Voltage U N U A Armature Current I A I N Excitation Current I f I N Torque T N T Power P N P Nominal Speed Trimmed Speed n max n April 18, 2011 Slide 59 If the basic speed range is too low but the available torque is sufficient, permanently field weakening the motor can expand the basic speed range. This is referred to as trimming. Adjustment of the base speed of DMI motors by speed trimming should not exceed 30% of the nominal base speed. 59

60 Electrical formulas T n [ Nm] = [ RPM] = P [ kw ] f n [ Hz] 9550 [ RPM] 120 polenumber Calculation of the torque [Nm]: Calculation of the nominal speed [rpm]: T = Torque [Nm] P = Output power [kw] n = Speed [r/min] April 18, 2011 Slide 60 In many cases motor selection can be calculated manually. The most important formulas can be found in this section. The basic formulas for calculating the torque and the nominal speed are shown in the slide. In the formulas: T = Torque [Nm], P = Output power [kw], and n = Speed [r/min]. If there is a gearbox between the driven equipment and the motor, the following things should be taken into consideration when selecting a motor: the power [kw] is equal for the both speeds, the torque [Nm] will vary according to the ratio, and the moment of inertia J [kgm2] varies quadratically to the ratio. 60

61 Formulas Motor torque 3,5 3 T / T N 2,5 2 1,5 1 0,5 T L Resultant operating point where load torque curve crosses motor torque / speed curve Load torque Speed r/min April 18, 2011 Slide 61 In this example case we select a suitable motor according to the following criteria: Fan or Pump duty = Quadratic torque LV cast iron motor Supply Frequency is 50Hz Supply Voltage is 400V Load speed range is r/min, and Load is 108 kw at approximately 1500 r/min. To choose the right motor, Calculate the torque with the formula T = 108kW x 9550 / 1500rpm) = 688NM. Check the catalogue. The nominal torque at least 688Nm. The correct motor type is M3BP 315SMA 4. 61

62 Different environments To choose the correct motor: 1. Calculate the efficiency and power factor. 2. Check the Motor guide for ambient factors. 3. Calculate the required output. 4. Check the efficiency in the Motor Guide. 5. Check the power factor in the Motor Guide. April 18, 2011 Slide 62 In this example we select the suitable motor type according to the following criteria and environmental conditions: LV cast iron motor, Ambient temperature +50oC, Altitude 2500 m, Class B temperature rise, 380 V, 50 Hz supply, and 55 kw, 988 RPM. To choose the correct motor: 1. Calculate the efficiency and power factor. 2. Check the Motor guide for ambient factors: Temperature x Altitude = 0.93 x 0.88 = Calculate the required output: At least (55kW / ) = 67.2 kw. Motor: M3BP 315SMA 6 (Nominal output 75kW). 4. Check the efficiency in the Motor Guide, page 66, table for Efficiency: 55kW / 75kW = 73% --> 75% Efficiency = Check the power factor in the Motor Guide page 69, table for Power Factor: 55kW / 75kW = 73% --> 75% Power Factor = Note that MotSize can be used for making the calculations and datasheets for LV motors, and Cuusamo for HV motors and generators. 62

63 Some useful conversion factors (US -> SI) Power: 1hp (UK, US) = kw Inertia: 1lb - ft2 = kgm2 Torque: 1 lb - ft = Nm 5 Temperature: C = ( F-32) 9 Mass: 1 lb = kg April 18, 2011 Slide 63 Here are some useful conversion factors from US to SI units. The conversion factors for power, inertia, torque, temperature, and mass are shown. 63

64 Starting methods: Direct-On-Line (DOL) starting Direct-on-line starter only required starting method when motor is connected directly to the mains supply Preferred starting method Limitation: high starting current April 18, 2011 Slide 64 The simplest way to start a squirrel cage motor is to connect it directly to the mains supply. When it is connected directly to the mains supply, a direct-on-line (DOL) starter is the only starting equipment required. However, the limitation with this method is that it results in a high starting current. Still, it is the preferred method, unless there are special reasons for avoiding it. 64

65 Starting methods: Y/D starting April 18, 2011 Slide 65 The graph shows a Y-D start where the starting current is about 2,2 times the nominal current. The torque values in the Y connection are much lower than in the D connection, which is why dimensioning motors for Y- D starts should be done with care, especially in bigger motors. If it is necessary to restrict the starting current of a motor due to supply limitations, the Y/D method can be employed. This method where, for instance, a motor wound 400 VD is started with the winding Y connected will reduce the starting current to about 30 per cent of the value for direct starting. The starting torque will be reduced to about 27 per cent of the DOL value. However, before using this method, one must first determine whether the reduced motor torque is sufficient to accelerate the load over the whole speed range. The starting time depends on the characteristics of the load and on the starting method. Large inertias of the load will cause long starting times, which can cause overheating in the motor. It is important to remember that the term starting current refers to the steady-state rms value. This is the value measured when, after a few cycles, the transient phenomena have died out. The transient current, the peak value, may be about 2.5 times the steady-state starting current, but it decays rapidly. The starting torque of the motor behaves in a similar way, and this should be taken into account if the moment of inertia of the driven machine is high, since the stresses on the shaft and coupling can be very great. Please contact your nearest sales office for the MotSize calculation program. 65

66 Starting methods April 18, 2011 Slide 66 The different starting methods of a motor are evaluated to satisfy the voltage drop requirement. 66

67 Power factor F USEFUL = F * cos ϕ APPARENT April 18, 2011 Slide 67 The relationship between the useful force and the apparent force is calculated as shown in the formula. 67

68 Power factor magnetic field Reactive power (VAR) Q Apparent power (VA) S ϕ P Active power (W) heat April 18, 2011 Slide 68 The power factor (=cos j) is a relevant characteristic of each motor, defining the active power used for running the motor. This factor also depends on the need for a magnetic field to create the flux: reactive power. 68

69 Power factor P INPUT = 3 *U*I* cosϕ April 18, 2011 Slide 69 The power factor indicates the need of reactive power Q compared with effective power P. A power factor of 1.0 means that the machine only draws effective power from the supplying network. The power factor of the induction motor should be Power factors are likely to be lower in certain special cases, for example with multi-speed motors, motors with a high pole number, down-rated motors, and motors with frame sizes below 100. The power factor is determined by measuring the input power, voltage, and current at the rated output. The effective input power (active power) in the motor is given by the formula. 69

70 Benefits of a high power factor Feasible to transmit only effective power through the electrical network Production or compensation can be made with synchronous machines or capacitors April 18, 2011 Slide 70 A high power factor has the following benefits: It is feasible to transmit only effective power through the electrical network, so if the motor draws reactive power from the network, Q should be produced somewhere near the load. Production or compensation can be made with synchronous machines or capacitors. Power companies charge more for this compensation than the price of effective power P, hence a high power factor is a desirable feature in an electrical motor. 70

71 April 18, 2011 Slide 71 71

72 K110e Unit 3 Basics of efficiency April 18, 2011 Slide 72 72

73 Efficiency April 18, 2011 Slide 73 ABB Motors are designed to meet changing world attitudes towards energy efficiency and motor performance. For instance, by increasing the efficiency in the production processes, and installing energyefficient devices, industrial processes will consume less electricity and by this play a significant part in reducing CO2 emissions. An energy-efficient motor produces the same output power (torque) but uses less electrical input power (kw) than a motor with lower efficiency 73

74 Efficiency, definition η = P Output Energy supply U I P cosφ P Input P Input rpm η = P Output + P Output Σ P Losses P Output load η = P Input Σ P Losses P Input P Losses Efficiency is ratio between mechanical output and electrical input High efficiency means that the motor is converting electrical power to mechanical power with small losses April 18, 2011 Slide 74 Efficiency is ratio between mechanical output and electrical input. To the left you can find the formula for energy efficiency. High efficiency means that the motor is converting electrical power to mechanical power with small losses. 74

75 Losses split into five major areas P input P iron P rotor P friction & windage P winding P input P output = Electrical power input = Mechanical power output P output Stator winding losses (P ws ) Rotor losses (P wr ) Iron losses (P fe ) P LL Additional load losses (P LL ) Additional load losses are due to: Friction + Windage losses (P fw ) leakage flux, mechanical imperfections in the air gap and irregularities in the air gap flux density April 18, 2011 Slide 75 Additional load losses (P LL ): Stray losses, all other losses ( ~ 15% of all losses). Additional load losses are losses that are not clearly or easily measured. indefinite. 75

76 Losses and efficiency in electrical motors Electrical energy in (P in ) P out 94 % P cu1 35 % Stator winding Mechanical energy out (P out ) Mechanical energy out Losses 6 % P cu2 20 % Rotor winding P Fe 20% Iron η P out = 100 x [%] P in P Fr Friction 10 % P LL 15 % Additional April 18, 2011 Slide 76 Description of typical losses for a LV motor, the percentage of all losses are given based on the old standard: Friction (P friction): Caused by the fan and bearings. This loss is independent of the load (P output) ( ~ 10% of all losses) Iron (P iron): Needed energy to magnetize the motor ( ~ 20% of all losses) Winding (P winding): Heat created by the current running in the windings ( ~ 35% of all losses) Rotor (P rotor): Heat created in the rotor ( ~ 20% of all losses) Additional load losses (PLL): All other losses ( ~ 15% of all losses). Additional load losses are losses that are not clearly or easily measured. 76

77 Efficiency measurement methods IEC ; 2007 IEC/EN : 2007 establishes harmonized methods for determining efficiencies of rotating electrical machines and also the methods of obtaining specific losses Covers asynchronous, synchronous and DC electrical machines Published by the International Electrotechnical Commission in September, 2007 April 18, 2011 Slide 77 The efficiency measure method was published by the International Electrotechnical Commission in September, The standard establishes harmonized methods for determining efficiencies of rotating electrical machines and also the methods of obtaining specific losses. It covers asynchronous, synchronous and DC electrical machines 77

78 Efficiency measurement methods IEC ; 2007 IEC offers two ways of measuring efficiency Direct method Measurement of the input power based on voltage and current, and the output power based on rotational speed and torgue No change compared to the old IEC Indirect method Measurement of the input power and calculation of the output power based on the losses of motor Specifies following parameters for measuring efficiency according to indirect method: Reference temperature Three alternatives for determining additional load losses Measurement Assigned value Mathematical calculation April 18, 2011 Slide 78 Using the direct method, the MECHANICAL power on the shaft and the ELECTRICAL power on the terminals have to be measured. The efficiency is then calculated as the ratio between the mechanical and the electrical power. As it is very difficult and expensive to purchase and maintain equipment to measure the exact mechanical power, the indirect method is used. Using indirect method, measurement of the torque and speed is carried out at different loads. Based on these measurements, the additional load losses are calculated. Indirect method is also called the summation of losses method. IEC s new method is closer to the IEEE method 78

79 IEC ; 2007 Losses and uncertainty of measurement Winding, rotor, iron and frictions losses can be determined from input power, voltage, current, rotational speed and torgue Additional losses P LL are much more difficult to determine IEC/EN specifies different methods to determine the additional losses : Low uncertainty measurement (IEEE 112-B & CSA390-98) Medium uncertainty assigned value and/or mathematical calculation High uncertainty assigned value Which method can be used depends on the motor efficiency class determined by IEC/EN April 18, 2011 Slide 79 You can find more detailed information about the low, medium and high uncertainty from Table 2 in the IEC/EN standard. IEC/EN defines which IE classes are connected to which method. 79

80 April 18, 2011 Slide 80 80

81 K110e Unit 4 General about standards April 18, 2011 Slide 81 81

82 Objectives This course module gives an overview of the standards concerning electrical motors and generators After successfully completing this module, you will be able to recognize the different electrical and mechanical requirements of the commonly used standards (IEC, NEMA) April 18, 2011 Slide 82 This course module presents a brief overview of the standards concerning electrical motors and generators. After successfully completing this module you will be able to recognize the different electrical and mechanical requirements of the commonly used standards IEC and NEMA. 82

83 Standard definitions Standard: technical specification or other document available to the public based on the consolidated results of science, technology and experience aimed at the promotion of optimum community benefits and approved by a body recognized on the national, regional or international level The most common standards in the motor business: IEC EN NEMA April 18, 2011 Slide 83 Standard is defined in the following way: "A technical specification or other document available to the public, drawn up with the cooperation and consensus or general approval of all interests affected by it based on the consolidated results of science, technology and experience, aimed at the promotion of optimum community benefits and approved by a body recognized on the national, regional or international level. In some languages the word "standard" is often used with another meaning than in this definition, and in such cases, it may refer to a technical specification which does not satisfy all the conditions given in the definition, for example: "company standard". ( ABB low voltage standard motors and generators are of the totally enclosed, three phase squirrel cage type, built to comply with international standard IEC-standards, CENELEC and relevant VDE-regulations, and DINstandards. Motors conforming to other national and international specifications are also available on request. All ABB motor production units are certified to ISO international quality standard and conform to all applicable EU Directives. ABB strongly supports the drive to harmonize European standards and actively contributes to various working groups within both IEC and CENELEC. 83

84 Standard definitions Directive: EC document issued by the European Community aimed at harmonizing national provisions to ensure the environment and safety aspects within each State published in the Official Journal of European Communities (OJEC) CE as proof of conformity to the following directives: Low Voltage Directive 73/23/EEC, amended by 93/68/EEC EMC Directive 89/336/EEC, amended by 92/31/EEC and 93/68/EEC April 18, 2011 Slide 84 A directive is an EC document issued by the European Community, the aim of which is to harmonize national provisions to ensure the environment and safety aspects within each State. A directive is published in the Official Journal of European Communities (OJEC). Products are stamped "CE" as proof of conformity to the following directives: Low Voltage Directive 73/23/EEC, amended by 93/68/EEC and EMC Directive 89/336/EEC, amended by 92/31/EEC and 93/68/EEC. Refer to the EC Declaration of Conformity delivered with each motor. 84

85 IECEx System The IECEx System is the International Electrotechnical Commission (IEC) System for the certification of equipment and services for use in explosive atmospheres The IECEx System was created in September 1999 IECEx certification is not the same as IEC certification, even though both relate to the same IEC standards The final objective of the IECEx System is worldwide acceptance of one standard, one certificate and one mark Four different certification Systems available More information about IECEx: April 18, 2011 Slide 85 The IECEx System is the International Electrotechnical Commission (IEC) System for the certification of equipment and services for use in explosive atmospheres. The IECEx System was created in September IECEx certification is not the same as IEC certification, even though both relate to the same IEC standards. The final objective of the IECEx System is worldwide acceptance of one standard, one certificate and one mark. There are four different certification Systems available: IECEx Certified Equipment System IECEx Certified Service Facilities System IECEx Conformity Mark Licensing System IECEx Certification of Personnel Competencies System More information about IECEx can be found from 85

86 Standard definitions The International Electrotechnical Commission (IEC): International standards and conformity assessment body for all fields of electrotechnology Created in 1906 Head office in Geneva, Switzerland Standards cover the whole electromechanical branch Status of the IEC standards not strong: national electrical standards are in common use in many countries April 18, 2011 Slide 86 The International Electrotechnical Commission (IEC) is the international standards and conformity assessment body for all fields of electrotechnology. It was created in 1906 and the commission's head office is situated in Geneva, Switzerland. The membership consists of more than 50 participating countries, including all the world's major trading nations and a growing number of industrializing countries. ( The standards cover the whole electromechanical branch. The essential content of the rotating electrical machine standardization is in section 34 "Rotating electrical machines", where there are 18 parts. Each part covers a particular issue in the rotating electrical machine s construction or performance. The main problem with the IEC standards is that their status in the world is not strong enough; national electrical standards are in common use in many countries. 86

87 Standard definitions The International Organization for Standardization (ISO): worldwide federation of national standards non-governmental organization established in 1947 The mission: to promote the development of standardization and related activities in the world to facilitate the international exchange of goods and services to develop cooperation in the spheres of intellectual, scientific, technological and economic activity April 18, 2011 Slide 87 The International Organization for Standardization (ISO) is a worldwide federation of national standards bodies from approximately 140 countries, one from each country. ISO is a non-governmental organization established in The mission of ISO is to promote the development of standardization and related activities in the world with a view to facilitating the international exchange of goods and services, and to developing cooperation in the spheres of intellectual, scientific, technological and economic activity. ISO's work results in international agreements that are published as International Standards. The scope of ISO is not limited to any particular branch; it covers all technical fields except electrical and electronic engineering, which is the responsibility of IEC. The work in the field of information technology is carried out by a joint ISO/IEC technical committee. 87

88 Standard definitions CENELEC: the European Committee for Electrotechnical Standardization established in 1973 as a non-profit-making organization under Belgian Law officially recognized by the European Commission as the European Standards Organization in its field in Directive 83/189/EEC works with 35,000 technical experts from 19 European countries to publish standards for the European market CENELEC standards covering the rotating electrical machines are harmonized with the IEC standards April 18, 2011 Slide 88 CENELEC is the European Committee for Electrotechnical Standardization. It was set up in 1973 as a nonprofit-making organization under Belgian Law. It was officially recognized by the European Commission as the European Standards Organization in its field in Directive 83/189/EEC. Its members have worked together in the interests of European harmonization since the late 1950s, developing alongside the European Economic Community. CENELEC works with 35,000 technical experts from 19 European countries to publish standards for the European market ( CENELEC standards covering the rotating electrical machines are harmonized with the IEC standards. CENELEC also includes standards for the construction and testing of electrical apparatus for use in potentially explosive atmospheres. 88

89 Standard definitions The National Electrical Manufacturers Association (NEMA): one of the leading standards development organizations in the world attempts to promote: the competitiveness of its member companies the establishment and advocacy of industry policies on legislative and regulatory matters the collection, analysis and dissemination of industry data April 18, 2011 Slide 89 The National Electrical Manufacturers Association (NEMA) has been developing standards for the electrical manufacturing industry for more than 70 years and is today one of the leading standards development organizations in the world. NEMA contributes to an orderly marketplace and helps ensure public safety. NEMA also attempts to promote: the competitiveness of its member companies by providing a forum for the development of technical standards that are in the best interests of the industry and the users of its products; the establishment and advocacy of industry policies on legislative and regulatory matters that might affect the industry and those it serves; and the collection, analysis and dissemination of industry data. NEMA publishes over 200 standards and offers them for sale along with certain standards originally developed by the American National Standards Institute (ANSI) and the International Electrotechnical Commission. The association promotes safety in the manufacture and use of electrical products, provides information about NEMA to the media and the public, and represents industry interests in new and developing technologies ( 89

90 IEC compared to NEMA Temperature rise: similar rules Tolerances: IEC defines some tolerances, but in NEMA standards these are so-called guaranteed values Methods of cooling and enclosure: IEC defines a very detailed numeric coding system, but NEMA standards are more general Starting characteristics: differences in the starting characteristics for normal starting torque cage motors; locked rotor apparent power versus kw rating is also different. April 18, 2011 Slide 90 Normally, if the NEMA standards are fulfilled, the corresponding IEC standards are also fulfilled. However, if the IEC standards are fulfilled, the corresponding NEMA standards are not necessarily fulfilled. The main differences and some comments on the similarities are discussed in the following: 1. Temperature rise: IEC and NEMA include similar rules for the adjustment of temperature rise as a function of non-standard coolant air, coolant water and/or altitude. There are some variations in the allowed temperature rise: a higher temperature rise is allowed in service factor 1.15 of the NEMA standard. Generally, a higher or equal temperature rise is allowed in the NEMA standards than in the IEC standards. Note that IEC and NEMA define the maximum allowed temperature rise in a different way when the ambient temperature is more than 40 ºC. 2. Tolerances: IEC defines some tolerances in efficiency, locked rotor current and power factor, but in the NEMA standards these are so-called guaranteed values. 3. Methods of cooling and enclosure: The IEC standards define a very detailed numeric coding system whereas the NEMA standards describe the cooling and enclosure systems more generally. 4. Starting characteristics: There are some differences in the starting characteristics for normal starting torque cage motors; locked rotor apparent power versus kw rating is also different. BU Motors and Generators strongly support the drive to harmonize European standards and actively contribute to various working groups within both the IEC and CENELEC. 90

91 April 18, 2011 Slide 91 91

92 K110e Unit 5 Electrical standards April 18, 2011 Slide 92 92

93 Electrical standards IEC Electrical standards: IEC : Rating and performance IEC : Methods for determining the losses and efficiency of rotating electrical machinery IEC : Terminal markings and direction of rotation of rotating machines IEC : (for LV only) Starting performance of single-speed three phase cage induction motors IEC/EN : 2008: Harmonization of efficiency classification standards April 18, 2011 Slide 93 Here is a list of the IEC Electrical standards. The IEC/EN standard was published by the International Electrotechnical Commission in October The standard defines new efficiency classes for motors. Target is to harmonize the different requirements for induction motor efficiency levels around the world. It provides a single international scheme for motor energy efficiency rating, measured by a common test method. 93

94 Motors covered in IEC/EN : 2008 IEC/EN covers almost all motors (for example standard, hazardous area, marine, brake motors): Single-speed, three-phase, 50 and 60 Hz 2, 4 or 6-pole Rated output from 0.75 to 375 kw Rated voltage U N up to 1000 V Duty type S1 (continuous duty) or S3 (intermittent periodic duty) with a rated cyclic duration factor of 80% or higher Excluded are: Motors made solely for converter operation Motors completely integrated into a machine (for example, pump fan or compressor) that cannot be tested separately from the machine April 18, 2011 Slide 94 IEC/EN covers almost all motors. Excluded are motors made solely for converter operation and motors completely integrated into a machine (for example, pump fan or compressor). 94

95 New efficiency classes defined by IEC/EN Premium efficiency IE3 Premium High efficiency IE2 Comparable to EFF1 Standard efficiency IE1 Comparable to EFF2 The standard also introduces IE4 (Super Premium Efficiency), a future level above IE3 efficiency values have yet to be defined for this class. April 18, 2011 Slide 95 The table shows the new efficiency classes defined by IEC/EN

96 IE efficiency classes for 50 Hz 4-pole motors EFF Classes 4 pole IE Classes 4 pole April 18, 2011 Slide 96 Here are the EFF- and IE efficiency classes for 4-pole motors illustrated. The standard also introduces IE4 (Super Premium Efficiency), a level above IE3. Please note that there is now a lowest level in efficiency, which was missing in the old CEMEP classification. 96

97 Electrical standards Type Tolerance Note Voltage deviation ±5% (+10K) ±10% Continuous Short time Power factor -1/6 of (1-cos) Min.0,02/Max.0,07 Efficiency -15% of (1- ) 10% of (1- ) P 2 < 50 kw P 2 > 50 kw Speed ± 20% of guaranteed slip Overspeed 120% for 2 min. Start torque 15 to + 25% Pull-up torque -15 % Maximum torque -10% Min. 160% of Mn Locked rotor current (or starting current) +20% April 18, 2011 Slide 97 The nominal tolerances given by the IEC are large and easily met; with the current manufacturing technology, the quality variation is smaller than that allowed by IEC. Some of our competitors may use this and ride with the IEC tolerances to gain benefit or hide their weaknesses. This line is not encouraged by ABB but is something worth keeping in mind. The table shows the eelectric tolerances according to IEC See the graph in the next slide for term definitions. 97

98 Electrical standards Maximum torque T MAX Starting current I s Locked-rotor current Starting torque T s Minimum torque T MIN Nominal torque T N Names in blue are IEC designations Names in black are NEMA designations April 18, 2011 Slide 98 The graph includes definitions for the terms used in the table shown in the previous slide. The graph illustrates the starting performance of an LV motor. 98

99 Electrical standards Θ Θ Θ Θ April 18, 2011 Slide 99 The duty types S1-S3 will be discussed in the following. S1 is a continuous duty that is an operation at constant load long enough for thermal equilibrium to be reached. S2 is a short time duty that is an operation at constant load for a given time that is shorter than the time needed to reach thermal equilibrium, followed by a rest and a de-energized period that is long enough to allow the motor to reach a temperature within 2 K of that of the coolant. S3 is an intermittent duty that is a sequence of identical duty cycles, each including a period of operation at constant load and a rest and a de-energized period. In this duty type the cycle of the starting current does not significantly affect the temperature rise. The load period is generally not long enough for thermal equilibrium to be reached. The illustration shows the characteristics of duty types S1, S2 and S3. In the illustration: P = output, PV = power losses, Q = temperature, tb = load period, ts = cycle duration, and tst = rest period. 99

100 NEMA MG 1 NEMA MG 1, Part 4 defines symbols for mounting dimensions Section I - General Standard Applicable to All Machines Section II - Small (Fractional) and Medium (Integral) Machines Section III - Large Machines April 18, 2011 Slide 100 NEMA MG 1, Part 4 defines symbols for mounting dimensions. It only defines dimensions up to frame number series 500 (shaft height 12.5" = mm). NEMA MG 1 consists of four sections, which are as follows: Section I, - General Standard Applicable to All Machines includes: Reference Standards and Definitions Terminal Markings Dimensions, Tolerances and Mounting Rotating Electrical Machines - Classification of Degree of Protection Provided by Enclosures for Rotating Machines Methods of Cooling (IC Code) and Mechanical Vibration - Measurement, Evaluation and Limits. Section II - Small (Fractional) and Medium (Integral) Machines includes: Small and Medium AC Motors Tests and Performance - AC and DC Motors Tests and Performance - AC Motors and Frame Assignments for Alternating Current Integral Horsepower Induction Machines. Section III - Large Machines: Induction Machines 100

101 How is the IE class marked? Example of the ABB s new rating plate Rating plate marking required The lowest efficiency value and the associated IE-code Efficiency at the full rated load and voltage (%), 75% and 50% Year of manufacture ABB has taken the new rating plate design into use in 2009 for all the motors valid according to IEC/EN As standard ABB will stamp 400V, 415V and 690V 50Hz and the efficiency value is given for 400V Material stainless steel April 18, 2011 Slide 101 IEC/EN defines: As a minimum, the lowest efficiency value and the associated IE-code (of all rated voltage/frequency/output combinations) shall always be printed on the rating plate. ABB will follow the standard. ABB motor design is normally optimized to 400V/50Hz operating point, and has highest efficiency in that point. Therefore 400V/50Hz value shall be the one we mark. If the motor is designed to other voltage/frequency, that will be the IE value stamped on the rating plate. All other voltage ratings, which have the same or higher efficiency may be in the same rating plate. Other ratings having lower IE value, need their own separate rating plate. ABB has taken the new rating plate design into use in Efficiency logo eff1 or eff2 has been removed and new IEC/EN defined IE rating must be in all our motors. 101

102 Rating plates April 18, 2011 Slide 102 The illustration shows examples of rating plates. The rating plate on the left is for an HV motor/generator according to IEC. The rating plate on the right is a typical rating plate of an AMA motor/generator according to NEMA. 102

103 Rating plates April 18, 2011 Slide 103 The rating plates are for LV motor according to NEMA. 103

104 Direction of rotation and terminal marking According to the IEC standard, the following terminal markings are required: windings are marked by letters (U, V, W), end points are marked with an additional numerical suffix (U1, V1, W1), and similar windings of a group are marked with a numerical prefix (1U, 1V, 1W). Direction of rotation is the one observed or clockwise April 18, 2011 Slide 104 According to the IEC standard, the following terminal markings are required: windings are marked by letters, end points are marked with an additional numerical suffix and similar windings of a group are marked with a numerical prefix. Direction of rotation is the one observed or clockwise. 104

105 Direction of rotation and terminal marking April 18, 2011 Slide 105 The illustration shows the connection diagram for main and auxiliary terminal boxes (HV motors). The connection diagram for the main and auxiliary terminal boxes gives the customer the necessary information for the main terminal cabling, control device cabling and layout. The following connections are shown in the connection diagrams: phases U, V, W (or T1, T2, T3 acc. to NEMA); temperature detectors in windings; anti condensation heaters; bearing temperature detectors; wire numbering (the same numbers are stuck onto the terminal blocks); and other specific order-related accessories. 105

106 Direction of rotation and terminal marking Diagram of connection Anschluss-Schema Schema de branchement Connection of terminals Anschluss des Motors Branchement des bornes W2 U2 V2 W2 U2 V2 W2 U2 V2 U1 V1 W1 L1 L2 L3 PE U1 V1 W1 Y-connection Y-Schaltung Connection etoile L1 L2 L3 PE U1 V1 W1 D-connection D-Schaltung Connection triangle Direction of rotation with phase sequence shown in picture Drehrichtung nach Schaltbild Direction de rotation avec branchement ci-dessus Direction of rotation with reversed phase sequence Drehrichtung mit umgekehrter Phasenfolge Direction de rotation avec sequence de phase reversée Motor No Maschine Nr No du moteur ABB Oy, Electrical Machines LV Motors 3GZF C April 18, 2011 Slide 106 The illustration shows a connection diagram for a main terminal box (LV motors). LV motors are supplied with a separate connection diagram for auxiliaries. 106

107 NEMA MG 1, Part 2 - Terminal Marking Terminal markings: line - L1, L2, L3, L4, etc. stator - T1, T2, T3, T4, etc. auxiliary markings, e.g. space heater H1, H2, H3, H4 April 18, 2011 Slide 107 NEMA MG 1, Part 2 covers terminal markings, direction of rotation, and the relation between the terminal markings and the direction of the rotation. The following terminal markings are covered: line (L1, L2, L3, L4, etc.); stator (T1, T2, T3, T4, etc.); also covers auxiliary markings, e.g. space heater H1, H2, H3, H4. The standard direction of rotation for AC generators is clockwise when facing the end of the motor/generator opposite the drive end (standard ABB practice is the IEC method). Terminal marking of polyphase induction motors/generators are not related to the direction of rotation. 107

108 Direction of rotation and terminal marking April 18, 2011 Slide 108 The illustration shows the connection diagram for main terminal box according to NEMA (LV motors). 108

109 April 18, 2011 Slide

110 K110e Unit 6 Mechanical standards April 18, 2011 Slide

111 Mechanical standards Shaft height Shaft height April 18, 2011 Slide 111 Shaft height is the distance from the centre line of the shaft to the bottom of the feet. For example, the motor type M3BP 315SMB 4 B3 has a shaft height of 315 mm. 111

112 Mechanical standards IM mounting arrangements IEC : Dimensions and output series for rotating electrical machines - Part1 IEC : Dimensions and output series for rotating electrical machines - Part2 IEC : Classifications of degrees of protection IEC : Methods of cooling IEC : Classification of types of construction, mounting arrangements and terminal box position (IM code) IEC : Noise limits (only low voltage motors) IEC : Measurement, evaluation and limits of vibration April 18, 2011 Slide 112 IM is an abbreviation for International Mounting. IEC defines the following mechanical standards: IEC covers the dimensions and output series for rotating electrical machines, part 1, frame numbers from 56 to 400 and flange numbers from 55 to IEC covers the dimensions and output series for rotating electrical machines, part 2, frame numbers from 355 to 1000 and flange numbers from 1180 to IEC covers degrees of protection provided by the integral design of rotating electrical machines (IP code) and classifications. IEC covers the methods of cooling. IEC covers the classification of types of construction, mounting arrangements, and terminal box position (IM code). IEC covers noise limits (only low voltage motors) IEC covers mechanical vibration of certain machines with shaft heights of 56 mm and higher, as well as measurement, evaluation, and limits of vibration. IEC defines symbols for the mounting dimensions and several different dimensions for symbols (footmounted: A, B, C; flange-mounted: M, N, P, R, S, T; shaft extension: D, E, F, GD, GE, GA). 112

113 Mechanical standards IM mounting arrangements April 18, 2011 Slide 113 The diagram shows an example of designations according to Code II. The first characteristic numeral indicates the basic construction of the motor/generator (mounting to foundation, bearing arrangement). The second and third numerals indicate more detailed construction, depending on the first numeral. The fourth numeral indicates the amount and shape of the shaft extension(s). IEC specifies two ways of stating how a motor is mounted. According to Code I, an alpha-numeric designation is applicable to motors/generators with end shield bearing(s) and only one shaft extension. According to Code II, an all-numeric designation is applicable to a wider range of types of motors/generators, including types covered by Code I. 113

114 Mechanical standards IM mounting arrangements Code II First numeral Second and third numeral Fourth numeral Motor/ generator type Code I Sketch IM 1001 Foot-mounted motors/generators with end shield bearing(s) only Two bearings, normal feet, feet down, shaft horizontal One cylindrical shaft extension HXR, AMA, AMK IM B3 IM 3011 Flange-mounted motors/generators with end shield bearing(s) only, with a flange as part of an end shield Two bearings, flange at D-end, access to back of flange, face of flange faces towards D-end, shaft vertical downwards One cylindrical shaft extension HXR IM V1 IM 4011 Flange-mounted motors/generators with end shield bearing(s) only, with a flange not part of an end shield but an integral part of the frame or other component Two bearings, flange at D-end, access to back of flange, face of flange faces towards D-end, shaft vertical downwards One cylindrical shaft extension AMA, AMK IM V10 April 18, 2011 Slide 114 The table shows examples of common HV motor mounting arrangements. 114

115 Mechanical standards IM mounting arrangements April 18, 2011 Slide 115 Examples of common LV motor mounting arrangements are shown in this slide. 115

116 Mechanical standards IM mounting arrangements Letter Numeral F - 1 April 18, 2011 Slide 116 The diagram above shows symbols for mounting arrangement for high voltage motors and generators according to NEMA MG 1. The letter indicates the mounting to the foundation, the numeral indicates the location of the terminal box. The illustrations below the diagram are examples of standard mountings (floor mounting). 116

117 International Standards Method of Cooling (IC code, short one normally used) IC = International cooling A = Air as coolant W = Water as coolant April 18, 2011 Slide 117 The diagram shows the method of cooling for low voltage motors according to IEC ABB can deliver motors as below: IC 410 Totally enclosed motor without fan IC 411: Totally enclosed standard motor, frame surface cooled with fan IC 416: Totally enclosed motor with auxiliary fan motor IC 418: Totally enclosed motor, frame surface cooled without fan IC 01 : Open motors IC 31W: Inlet and outlet pipe or duct circulated: water cooled Note: Motors without fan can deliver same output power provided installation are according to IC

118 International Standards Method of Cooling COMPLETE DESIGNATION SIMPLIFIED DESIGNATION IC 8 A IC 8 1 W 7 1 W Code letters Circuit arrangement Primary coolant Method of movement of primary coolant Secondary coolant Method of movement of secondary coolant April 18, 2011 Slide 118 The diagram shows the method of cooling for high voltage motors and generators. 118

119 International Standards Method of Cooling Characteristic numeral Circuit arrangement Method of movement 0 Free circulation Free circulation 1 Inlet pipe or inlet duct-circulated Self-circulation 2 Outlet pipe or outlet duct-circulated - (reserved for future use) 3 Inlet and outlet pipe or duct-circulated - 4 Frame surface-cooled - 5 Integral heat exchanger (using surrounding medium) Integral independent component 6 Motor/generator mounted heat exchanger (using surrounding medium) Motor/generator-mounted independent component 7 Integral heat exchanger (using remote medium) Separate and independent component or coolant system pressure 8 Motor/generator-mounted heat exchanger (using remote medium) 9 Separate heat exchanger (using surrounding or remote medium) Relative displacement All other components April 18, 2011 Slide 119 The table shows the characteristic numeral for circuit arrangement as well as the method of movement. 119

120 International Standards Method of Cooling Characteristic letter A F H N C W U S Y Coolant Air Freon Hydrogen Nitrogen Carbon dioxide Water Oil Any other coolant Coolant not yet selected April 18, 2011 Slide 120 The table shows the characteristic letter for each coolant. 120

121 Symbols for degree and protection IP code IEC and NEMA MG 1 Part 5 April 18, 2011 Slide 121 In the International Protection code (IP code), the first characteristic numeral indicates the degree of protection against contact and ingress of foreign bodies and the second indicates the degree of protection against ingress of water. When necessary, the degrees of protection for electrical motors/generators may have the following letters added after the second numeral: W = open weather-protected motor/generator (NEMA specifies after the IP Code), S = motor/generator tested for harmful ingress of water at standstill, and M = motor/generator tested for harmful ingress of water when running. IP protection is protection of persons against getting in contact with (or approaching) live parts and against contact with moving parts inside the enclosure. Also protection of the machine against ingress of solid foreign objects. Protection of machines aginst the harmful effects due to the ingress of water. Classification of degrees fo protection provided by enclosures of rotating machines refers to Standard IEC or EN for IP code. 121

122 Protection Classes (IEC ) April 18, 2011 Slide 122 The table shows the explanations of the protection codes. 122

123 Protection Classes (IEC ) Protection Brief Description Definition Cooling Motor/ NEMA generator type IP23 Motor/generator protected against solid objects greater than 50 mm ( in) Motor/generator protected against spraying water Contact with or approach to live or moving parts inside the enclosure by fingers or similar objects not exceeding 80 mm ( in) in length. Ingress of solid objects exceeding 12 mm ( in) in diameter. Water falling as a spray at an angle up to 60 from vertical shall have no harmful effect. IC01 AMA, AMK ODP IP24W (IEC) IPW24 (NEMA) Motor/generator protected against solid objects greater than 50 mm ( in) Motor/generator protected against spraying water Contact with or approach to live or moving parts inside the enclosure by fingers or similar objects not exceeding 80 mm ( in) in length. Ingress of solid objects exceeding 12 mm ( in) in diameter. Water splashing against the machine from any direction shall have no harmful effect. Weather-protected so designed that ingress of rain, snow and airborne particles into the electrical parts is reduced. IC01 AMA, AMK WP I WP II IP55 Dust-protected motor/generator Motor/generator protected against water jets Contact with or approach to live or moving parts inside the enclosure. Ingress of dust is not totally prevented but dust does not enter in sufficient quantity to interfere with satisfactory operation of the machine. Water projected by a nozzle against the machine from any direction shall have no harmful effect. IC411 IC611 IC81W HXR AMA, AMK AMA, AMK TEFC TEAAC TEWAC April 18, 2011 Slide 123 The table shows the standard IP protection for high voltage motors and generators. 123

124 Degrees of protection IK code April 18, 2011 Slide 124 IK code is the classification of degrees or protection provided by enclosure for motors against external mechanical impacts. Classification of degrees fo protection provided by enclosures of rotating machines refers to Standard EN for IK code. 124

125 Insulation April 18, 2011 Slide 125 ABB uses class F insulation systems, which, with temperature rise B, is the most common requirement among industry today. The use of Class F insulation with Class B temperature rise gives ABB products a 25 C safety margin. This can be used to increase the loading by up to 12 per cent for limited periods, to operate at higher ambient temperatures or altitudes, or with greater voltage and frequency tolerances. It can also be used to extend insulation life. For instance, a 10 K temperature reduction will extend the insulation life. Class F insulation system Max ambient temperature 40 C Max permissible temperature rise 105 K Hotspot temperature margin + 10 K Class B rise Max ambient temperature 40 C Max permissible temperature rise 80 K Hotspot temperature margin + 10 K Insulation system temperature class Class F 155 C Class B 130 C Class H 180 C 125

126 Frequency converter drives Customer values April 18, 2011 Slide 126 Squirrel cage induction motors offer excellent availability, reliability and efficiency. With a frequency converter a variable speed drive (VSD) the motor will deliver even better value. A variable speed drive motor can be started softly with low starting current, and the speed can be controlled and adjusted to suit the application demand without steps over a wide range. Also the use of a frequency converter together with a squirrel cage motor usually leads to remarkable energy and environmental savings. Speed control has several benefits: it allows accurate process control, and thus creates better end product quality. Speed control also creates less stress to mechanics and electrical network due to soft starting and precise control. It increases production capacity without additional investments. An AC induction motor, that is, an asynchronous squirrel cage AC motor, is most commonly used in industry. It has some basic advantages like robust design, simple construction, high IP class, and so on. An asynchronous motor needs frequency converter to control its speed. A modern frequency converter has many advanced protection features that protect the drive itself, equipment connected to the drive and even the production process. It has inbuilt programmability that allows it to control a production process without an additional external controller, or PLC. Programmability means the user can fine tune the variable speed drive, or VSD, to get the most out of the whole equipment. Requirements for the flexibility and accuracy of external control methods can best be fulfilled with a modern VSD which can be connected to just about any fieldbus or analog or digital control signal. Even remote monitoring via the Internet is possible. 126

127 Rotor Construction Balancing Standards for mechanical vibration: ISO 1940/1: Balance quality requirements for rigid rotors, Part 1 ISO 1940/2: Balance quality requirements for rigid rotors, Part 2 ISO 11342: Methods and criteria for the balancing of flexible rotors Balancing quality grades: G2, 5 for medium and large armatures with special requirements G6, 3 for medium and large armatures without special requirements April 18, 2011 Slide 127 The following standards cover the balancing of the rotor construction: ISO 1940/1 for mechanical vibration covers the balance quality requirements for rigid rotors in Part 1: Determination of permissible residual unbalance. ISO 1940/2 for mechanical vibration covers the balance quality requirements for rigid rotors in Part 2: Balance errors. ISO for mechanical vibration covers the methods and criteria for the balancing of flexible rotors. Imbalance is a condition, which exists in a rotor when a vibratory force or motion is imparted to its bearings as a result of centrifugal forces. The balancing quality grades are: G2, 5 for medium and large armatures with special requirements and G6, 3 for medium and large armatures without special requirements. As standard, rotors are balanced with half key; the coupling must also be balanced with half key. The balancing procedure is permanently marked on the shaft end with 'H' (H = half key, F = full key). 127

128 Vibration Vibration is a response of a system to an internal or external stimulus causing it to oscillate or pulsate Three important parameters: frequency amplitude phase April 18, 2011 Slide 128 Vibration is the response of a system to an internal or external stimulus causing it to oscillate or pulsate. While it is commonly thought that vibration itself damages motors and structures, it does not. The damage is done by dynamic stresses that cause fatigue in the materials. The dynamic stresses are included in the vibration. Vibration has three important parameters, which can be measured: Frequency, that is, how many times does the motor or structure vibrate per minute or per second. Amplitude, that is, how much is the vibration in microns, mm/s or g's. Phase, that is, how is the member vibrating in relation to the reference point. The following standards cover mechanical vibration: ISO Mechanical vibration: Evaluation of machine vibration by measurement of non-rotating parts, NEMA MG 1, Part 7: Mechanical vibration - Measurement, evaluation and limits, ISO 7919: Mechanical vibration of non-reciprocating machines - Measurement of rotating shafts and evaluation criteria, and IEC : Mechanical vibration of certain machines with shaft heights of 56 mm and higher - Measurement, evaluation and limits. 128

129 M, IP, IC International Standards CEI EN 60034: CEI EN : degrees of protection provided by the integral design of rotating electrical machines (IP code) Classification, CEI EN : degrees of protection provided by the integral design of rotating electrical machines (IP code) Classification, and CEI EN : classification of types of construction, mounting arrangements and terminal box position (IM Code). April 18, 2011 Slide 129 The following issues are covered by the International Standards CEI EN 60034: CEI EN covers the degrees of protection provided by the integral design of rotating electrical machines (IP code) Classification, CEI EN covers the degrees of protection provided by the integral design of rotating electrical machines (IP code) Classification, and CEI EN covers the classification of types of construction, mounting arrangements and terminal box position (IM Code). 129

130 April 18, 2011 Slide