Electrostatic Spray Painting

Transcription

1 Positive spray gun Electrostatic Spray Painting Static electricity can be used in spraying liquids e.g. spraying pesticides, spray painting The car gains electrons The gun looses electrons so the paint looses electrons The paint spreads out as each positive drop repels No paint is wasted as the negative car attracts the positive paint Negative car 1 Electrostatic Spray Painting During car production, the unpainted car body and the paint are given opposite electric charges. Unlike charges attract, so: The paint sticks to every corner of the car body The paint covers the car body evenly. 2

2 Electrostatic Precipitators Principle: Electrodes at high voltage create a corona effect (ionized atmosphere) surrounding them. This charges the passing particles. Once charged, particles are subject to a transverse electrostatic force that pulls them toward the collecting plates. Plates are periodically rapped (vibrated) to make the collected particles fall down into a receiver basket. 3 Static Electricity in a Photocopier (1) & (3) drum inside is charged. Light reflects an image of document on drum. Dark areas (writing and images on the original) retains a positive charge. (4 & 5) Charged parts of the drum attracts the negatively-charged toner ink (black powdered particles). (6) Toner ink transferred from drum to positively-charged paper, producing a copy of original. 4

3 The Xerographic Process 5 Applications of Electric Motors In an average American home, a total of approx. 125 motors accounts for 43% of the electricity consumption. 6

4 Basic Principles DC Motor By keeping flux constant, torque can be controlled by controlling armature current φ a T e = k I f I a φ f Current in Current out 7 DC Motor - Construction 8

5 Carbon brushes 9 AC Induction Motor 10

6 Three Phase Rotating Fields 11 Rotating Field 12

7 Operation Principle The rotating flux induces a voltage in the shortcircuited bars of the rotor. This voltage drives current through the bars. The induced voltage is proportional with the difference of motor and synchronous speed. Consequently the motor speed is less than the synchronous speed. Induction Motors The interaction of the rotating flux and the rotor current generates a force that drives the motor. The force is proportional with the flux density and the rotor bar current 13 Induction Motors Squirrel cage rotor. This rotor has a laminated iron core with slots, and is mounted on a shaft. Aluminum bars are molded in the slots and the bars are short circuited with two end rings. The bars are slanted on a small rotor to reduce audible noise. Fins are placed on the ring that shorts the bars. These fins work as a fan and improve cooling. 14

8 Induction Motors (5) 15 Rotor of Induction Motor Difference between angular velocity of rotor and angular velocity of the rotating field causes squirrel cage bars to cut the field magnetic field inducing current into squirrel cage bars. This current in turn magnetizes the rotor 16

9 Slip of Induction Motor Slip s = ϖ ϖ s ϖ s r 17 Torque Speed Curve 18

10 AC Permanent Magnet Motors New Designs for Compact Gearless Machines Torque Strength from Permanent Magnets 90 95% Efficient Compatible with Inverters to Control Speed Requires Synchronous Flux Vector / Angle Control to Regulate / Modulate Torque Supply Limited to Specialty Machine Builders Not Suitable for High Speed Geared Designs Can Act Like a Generator 19 AC Permanent Magnet Motor Three phase AC current Three phase AC current Phase 1 Coil 1 Phase 1 Coil 1 Phase 2 Coil 2 Phase3 Coil 3 Phase 2 Coil 2 Phase3 Coil 3 20

11 KONE EcoDisc 21 Rare-earth PM challenge Since early 2011, prices of NdFeB PMs have been increasing considerably, due to China s limited quotas and raised taxes on rare-earths exports. Increasing price of rare-earth magnets poses a possibility of magnet manufacturing in other countries, including Brazil. Prices of Rare-earth magnets are not stabilized yet. Search for efficient but non-rare-earth motor technologies Neodymium Samarium 22

12 The Electrical Elevator/Lift A permanent lifting equipment serving two or more landing levels, including a car for transportation of passengers, goods, running al least partially between rigid guide rails. 23 Brief History of Lift 236 BC First Passenger Lift, Archimedes 1853 Safe Elevator Demo, Elisha Otis 1857 First Safe Elevator Installation, Cooper Union, NYC 1861 Otis Elevator Patent 24

13 Brief History of Lift 25 Brief History of Lift 1873 First Modern DC Motor 1874 J. W. Meaker Door Opener Patent 1880 First Electric Motor Controlled Elevator Siemens / Sprague Tesla AC Induction Motor 3-Phase Squirrel Cage Design 1889 Otis Elevator uses DC Motor 26

14 Brief History of Lift Otis DC Elevator Motor Brief History of Lift 1891 Ward Leonard Variable Speed Control AC induction motor turning DC generator Rheostat to control the generated voltage DC Voltage Controls DC Motor Speed s Ward-Leonard M-G Sets and DC Motors used for Variable Speed Elevators AC Motors used 1 and 2 Speed Starters 28

15 Otis No. 1 Geared DC Machine (1915) 29 Otis Gearless DC Machine (1919) 30

16 M-G Set Controls (Otis Elevator, 1920 s) 31 Otis Type 84 Broadway,NYC 1930 s 32

17 Brief History of Lift 1975-Present Thyristor (SCR) DC drives All analog components in the 70 s Replaces aging M-G Sets 1980 s Microprocessors Improve Car Dispatch and Motor Drive Controllers 33 Elevator Control System Elevator Control System is the system responsible for coordinating all aspects of elevator service such as travel, speed, and accelerating, decelerating, door opening speed and delay, leveling and hall lantern signals. It accepts inputs like (button signals) and produces outputs like (elevator cars moving, doors opening, etc.). 34

18 Aims of the control system To bring the lift car to the correct floor. To minimize travel time. To maximize passenger comfort by providing a smooth ride. To accelerate, decelerate and travel within safe speed limits. 35 relay logic solid state 32-bit microprocessor 36

19 Brief History of Lift Late 1980 s Variable Frequency Inverters AC Induction Motors, Geared applications only Early 1990 s More AC inverters and motors begin to displace small DC, 3-15 HP Mid-1990 s Vector Control AC Inverters HP almost as good as SCR-DC. KONE Introduces PM EcoDisc AC Machine 37 Brief History of Lift Late 1990 s Custom Gearless AC Induction Machines First Fully Regenerative AC Elevator Drives Much Discussion on PM-AC and Machine Room- Less (MRL) SCR-DC still used for medium and large building 38

20 Brief History 2000-Present More PM-AC Motor manufacturers. PM Gearless begins to replace AC Geared EU focus on efficiency and harmonics/emc Lower cost IGBT inverter components North America begins to focus on energy reduction New construction leaning toward AC SCR-DC still used 39 Basic Components of Traction Elevators - Controller Machine room - - Motor with sheave - Speed governor Car - - Guide rails - Counter weights Hoistway doors -

21 Operating Modes Speed Profile Lift Car Typical Speed Profile Acc/Dec normally limited to m/s 2 Jerk normally limited to 1 m/s 3 42

22 DC Lift Drive Power Regeneration DC-motor, SCR drive 80m / 3.6m/s / 1600kg 60 Motor power Motor Power [kw] velocity Time [s] Lift System Configuration 44

23 Elevator Machine and Drive System Driving machine is the power unit of the elevator, and usually located at the elevator machine room. The Driving machine used to refer to the collection of components that raise or lower the elevator. These include the drive motor, brake, speed reduction unit, sheaves and encoders. 45 Hoistway Hoistway is the space enclosed by fireproof walls and elevator doors for the travel of one or more elevators, dumbwaiters or material lifts. It includes the pit and terminates at the underside of the overhead machinery space floor or grating or at the underside of the roof where the hoistway does not penetrate the roof. (Hoistway is sometimes called "hatchway" or "hatch".) 46

24 Hoistway 47 Landing (Hoistway) Doors The door that is seen from each floor of a building is referred to as the outer or hoistway door. This hoistway door is a part of the building (each landing). It is important to realize that the car door does all the work; the hoistway door is a dependent. These doors can be opened or closed by electric motors, or manually for emergency incidents. 48

25 Landing Door 49 Hoisting Cables (or ropes) Suspension Ropes are Suspension means for car and counterweight, which are represented by steel wire ropes. They are used on traction type elevators, usually attached to the crosshead and extending up into the machine room looping over the sheave on the motor and then down to the counter weights. 50

26 Hoisting Cables (or ropes) Sheave 51 Hoisting Cables (or ropes) traditional rope new flat belt 52

27 Elevator Car Elevator Car is the vehicle that travels between the different elevator stops carrying passengers. It is usually a heavy steel frame surrounding a cage of metal and wood panels. 53 Elevator Car Cross head 54

28 Guide Rails Roller guides on Cross head 55 Counterweight Counterweight is a tracked weight that is suspended from cables and moves within its own set of guide rails along the hoistway walls. Counter weight The elevator car is balanced by a heavy counterweight that weighs roughly the same amount as the car when it's loaded half-full. 56

29 Brake Traction machines are provided with a mechanical brake, designed to stop and safely hold an elevator. A centrifugal force governor is provided on most elevators to guard against over speeding (when a car travels in excess of 20% of top speed, the governor will activate a safety stop device). Safeties are installed at the bottom of an elevator car and occasionally on counterweights to provide positive emergency stopping when activated by the governor. 57 Brake 58

30 Governor and Safety Clamp Governor rope 59 Progressive Safety Gear Safety gear is a mechanical device for stopping the car (or counterweight) by gripping the guide rails in the event of car speed attaining a pre-determined value in a downward direction of travel, irrespective what the reason for the increase in speed may be. 60

31 Buffers in the pit A Buffer is a device designed to stop a descending car or counterweight beyond its normal limit and to soften the force with which the elevator runs into the pit during an emergency. They may be of polyurethane or oil type in respect of the rated speed. 61 Buffers 62

32 Safety system Safety system components: 1- Device for locking landing doors (Hoistway Door Interlock). 2- Progressive safety gear. 3- Overspeed governor. 4- Buffers. 5- Final Limit switches. 6- Other safety devices and switches. 63 Car Positioning Every Floor Top of Car 64

33 Car Positioning 65 Geared Traction Elevator Geared traction machines are driven by AC or DC electric motors, they use gears to control mechanical movement of elevator cars by rolling steel hoist ropes over a drive sheave which is attached to a gearbox driven by a high speed motor. These machines are generally the best option for basement or overhead traction use for speeds up to 2.5 m/s. In order to allow accurate speed control of the motor, to allow accurate leveling and for passenger comfort, a DC hoist motor was the preferred solution in high-traffic elevator installations for many decades. 66

34 Gearless Traction Drive Gearless traction machines are low speed (low RPM), high torque electric motors powered either by AC or DC. In this case, the drive sheave is directly attached to the end of the motor. Gearless traction elevators can reach speeds of up to 10 m/s, or even higher. A brake is mounted between the motor and drive sheave (or gearbox) to hold the elevator stationary at a floor. This brake is usually an external drum type and is actuated by spring force and held open electrical. a power failure will cause the brake to engage and prevent the elevator from falling. 67 Geared and Gearless Drives 68

35 ThyssenKrupp Elevator: TWIN Two independent cars in one shaft Save the building space, reduce waiting time and increase the capacity. Buildings floors can exceed 100. Landing floor selection system TWIN panorama elevator 1350kg, 2.5m/s, 60m Counterweight 69 Hydraulic Elevators Conventional hydraulic elevators: They use an underground cylinder, are quite common for low level buildings with 2-5 floors (sometimes but seldom up to 6-8 floors), and have speeds of up to 200 feet/minute (1 meter/second). Holeless hydraulic elevators were developed in the 1970s, and use a pair of above ground cylinders, which makes it practical for environmentally or cost sensitive buildings with 2, 3, or 4 floors. Roped hydraulic elevators use both above ground cylinders and a rope system, which combines the reliability of inground hydraulic with the versatility of holeless hydraulic, even though they can serve up to 8-10 floors. The low mechanical complexity of hydraulic elevators in comparison to traction elevators makes them ideal for low rise, low traffic installations. The main disadvantage is their lower efficiency with no counterbalancing, they require more power to operate. The design of a hydraulic elevator is shown in the next slide. 70

36 Hydraulic Lifts Piston and cylinder Hydraulic oil reservoir Pump and piping Control system 71 Hydraulic Pump 72

37 Guide Rails Guide rail Guide rail 73 Elevator Technologies Summary 74

38 Escalators Jesse Reno, a graduate of Lehigh University, produced the first working escalator (he actually called it the "inclined elevator") and installed it alongside the Old Iron Pier at Coney Island, New York in Piat installed its "stepless" escalator in Harrods Knightsbridge store on Wednesday, November 16, 1898 Customers were given Brandy to recover from the experience! 75 Escalators A single 1m wide escalator can move up to 4500 passengers in an hour Can be used in stacks to cover up to 4 floors Suitable for able bodied adults Not unsupervised children, persons with disabilities or elderly persons. 76

39 Step Each step in the escalator has two sets of wheels, which roll along two separate tracks. The upper set (the wheels near the top of the step) are connected to the rotating chains, and so are pulled by the drive gear at the top of the escalator. The other set of wheels simply glides along its track, following behind the first set. 77 Step Chain Drive The Step Chains are endless links connected with link pins to make a complete loop and are attached to an axle on each side of the steps forming a loop which runs for the length of the truss from the upper Main Drive Axle to the lower Tension. 78

40 Step Chain Drive 79 Handrail The Handrail provides a convenient handhold for passengers. The Handrail is constructed of four distinct sections. At the center of the handrail is a "slider. The next layer, known as the tension member consists of either steel cable or flat steel tape. On top of the tension member are the inner construction components. Finally, the outer layer, which is a blend of synthetic polymers and rubber. 80

41 Basic components of an escalator 81 Moving Walks Available as flat walkways to reduce walking times Or inclined at up to 12 degrees (10 degrees is best) Can transport up to 3600 passengers per hour Or 900 shopping trolleys with passengers Not suitable for unsupervised children, the elderly and disabled 82

42 Moving Walks 83 Other Escalators 84