EE1PEEE Refresher Class

Power Part 3

notes by T. Ernst

EE1 – Power Part 3 Notes Fall 2011, Page 1

Fall 2011, Page 2

EE1 – Power Part 3 Notes

• Induction Machines• Motors• Generators

• Synchronous Machines• Motors• Generators

• Double fed induction (variable speed synchronous)

Fall 2011, Page 3

EE1 – Power Part 3 Notes

Induction Motors•Squirrel cage

Fall 2011, Page 4

EE1 – Power Part 3 Notes

Only generate torque when slip is not equal to 0•Slip frequency [hz]•Slip speed [RPM]

Fall 2011, Page 5

EE1 – Power Part 3 Notes

Synchronous speed f(frequency & poles)

Fall 2011, Page 6

EE1 – Power Part 3 Notes

What is the difference between a motor and a generator?•Slip?•Power transfer?

Fall 2011, Page 7

EE1 – Power Part 3 Notes

Induction motor nameplate

Fall 2011, Page 8

EE1 – Power Part 3 Notes

Induction motor nameplate

Fall 2011, Page 9

EE1 – Power Part 3 Notes

Fall 2011, Page 10

EE1 – Power Part 3 Notes

Fall 2011, Page 11

EE1 – Power Part 3 Notes

Locked rotor current example: 250 HP, code F

Fall 2011, Page 12

EE1 – Power Part 3 Notes

Locked rotor equivalent impedance

Fall 2011, Page 13

EE1 – Power Part 3 Notes

If FL (250 HP) speed is 3450 RPM, what is speed at 200 HP?

Fall 2011, Page 14

EE1 – Power Part 3 Notes

Fall 2011, Page 15

EE1 – Power Part 3 Notes

Fall 2011, Page 16

EE1 – Power Part 3 Notes

Reduced Voltage Starting•Auto-transformer•Series inductor

Fall 2011, Page 17

EE1 – Power Part 3 Notes

Reduced Voltage Starting• ½ - ½ • Wye start – delta run