PAC TRAINING PUMP MOTORS

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Horatio Sparks
5 years ago
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1 PAC TRAINING PUMP MOTORS 1

2 Basics Magnet supported from above N S N S Since unlike poles repel each other, the magnet will rotate Stationary Magnet 2

3 Basics N S Stationary Magnet 3

4 Basics N N S S Stationary Magnet 4

5 Basics N S Stationary Magnet 5

6 Basics S N When the unlike poles are lined up with each other, rotation will stop N S Stationary Magnet 6

7 BASIC THEORY OF MOTORS Machines that convert electrical energy to rotary or linear motion via electro-magnetic induction Motors consist of two basic electrical assemblies: wound stator & rotor assembly Rotor: laminated cylindrical iron cores with evenly spaced bars of copper /aluminium. Stator: consisting of insulated windings -start and run windings 7

8 Parts of an electric motor Housing and Stator Electrical Connections Rotor End Bell Mounting Base Shaft 8

9 c.s.a of a motor 1. Shaft with key 2. Ring of the squirrel cage 3. Terminal box 4. Cooling fan 5. Stator end-winding 6. Stator 7. Rotor 8. Motor case 9

10 THREE PHASE vs SINGLE PHASE Three phase -Allows motor to be self starting Single phase Starting mechanism for motor necessary. L1 L2 L3 THESE THREE POWER SUPPLIES ARE GENERATED 120 DEGREES OUT OF PHASE WITH EACH OTHER 10

11 GRID VOLTAGES KE / 415 ET - 220/380 RW 220/380 UK - 240/415 Equipment with CE mark 230 ± 10% 11

12 SINGLE PHASE AC MOTORS Up to 2.2kW Types: Resistance Start Induction Run Motor Permanent Split Capacitor Capacitor Start Induction Run Capacitor Run Capacitor Run 12

13 Single phase motors 13

14 Resistance Start Induction Run (RSIR) Motor Smaller wire size for start winding-higher resistance than run winding. Low starting torque Pros-no capacitors Cons-limited starting torque, limited kw ratings (up to 1.1kW) 14

15 Permanent Split Capacitor (PSC) Motor Run type capacitor in circuit Pros-Simple, low cost, reliable Cons-low locked rotor torque and efficiency 15

16 Capacitor Start Induction Run (CSIR) Motor Start cap boosts torque during start up-then disconnected by switch Pros-Locked Rotor Torque Cons-Noisy, relay used to cut out start capacitor 16

17 Capacitor Start Capacitor Run (CSCR) Motor Start capacitor boosts starting torque; run capacitor ensures smooth operation and boosts efficiency. Pros-Good starting torque, high efficiency Cons-Price of control box 17

18 THREE PHASE PHASE AC MOTORS Induction (squirrel cage & slip ring or synchronous among others) Commonest are squirrel cage since they are robust & comparatively cheaper 18

19 Starting Methods of Three Phase Motors High starting current- 5 to 10 times the full load current. Results in huge voltage drop on Mains. Different starting methods used to comply to local laws and regulations Common methods: DOL, Star Delta, Auto Transformer, Soft Starter, VFD. 19

20 DOL STARTING STAR-DELTA STARTING 20

21 DOL, STAR-DELTA STARTING 21

22 Direct-on-line starting Simple and cost efficient Highest possible starting torque High locked rotor current Used for motors <7.5kW Star Delta starting Reduction of locked rotor current by factor of 3 Reduced locked rotor torque Not suitable if the load has low inertia for instance borehole pumps Used for motors 7.5kW or greater. 22

23 Connection of Three Phase Motor 23

24 Mainly caused by: Power supply Motor Failure Motor operating conditions Motor installation conditions The breakdowns can be further divided into: Thermal Mechanical Environmental 24

25 Overload Thermal Breakdown Causes Voltage fluctuations Single phasing Short cycle Surges Improper ventilation Dirt and dust accumulation 25

26 Vibration Mechanical Breakdown Causes Improper alignment Bearing failure resulting in insulation rubbing of rotor and stator Bearing failure due to: Improper lubrication Excessive belt tension Mis-alignment 26

27 Moisture/Water Environmental Breakdown Causes Corrosion/Chemicals Rodents/Insects Age 27

28 Why motor fail... Bearing Failures 13% Rotor Failures 5% Overload 30% Contaminants 19% Misc 9% Old Age 10% Single Phasing 14% 28

29 Motor Performance as voltage varies 29

30 Motor Efficiency IE4-Super Premium IE3-Premium IE2-High IE1-Standard 30

31 Effect of (under)loading on efficiency & power factor 31

32 Conclusion Motors will last along time if operated within design parameters (voltage, current and temperature) Rules of thumb: A 10 C temperature rise above rated temperature will half the life of a motor A 3.5% voltage unbalance will cause a 25% temperature rise 32

Starting of Induction Motors

Starting of Induction Motors 1- Star Delta Starter The method achieved low starting current by first connecting the stator winding in star configuration, and then after the motor reaches a certain speed, throw switch changes the winding