1. Star-delta motor starting is sometimes called double-delta starting.
a. True
b. False
2. Star-delta motors are similar in construction to standard squirrel cage motors.
a. True
b. False
3. Star-delta motors may be used where a reduced starting current is required.
a. True
b. False
4. A disadvantage of open transition starting is that it does not require accessory voltage reducing equipment.
a. True
b. False
5. Closed transition starting is accomplished by adding another three pole contactor and resistors to the circuit.
a. True
b. False
Name: Class: Date:
Unit 29 Automatic Starters for Star-Delta Motors
6. Star-delta motors are widely used on loads having high inertia and a ____.
a. lagging power factor b. reversing winding arrangement
c. 40C rating d. long acceleration period
7. The speed of a star-delta, squirrel cage induction motor depends on the number of poles of the motor and the supply
line ____.
a. resistance b. capacitance
c. frequency d. temperature
8. If the motor nameplate indicates only the delta-connected full-load current, divide this value by ____ to obtain the
winding current.
a. 1.73 b. 3.14
c. 6.33 d. 10
9. Wye-delta starting is accomplished by connecting the ____ in wye during the starting period and then reconnecting
them in delta for normal run operation.
a. stator windings
b. overload relays
c. timer contacts
d. motor terminals
Name: Class: Date:
Unit 29 Automatic Starters for Star-Delta Motors
10. Open transition starting may be objectionable in some applications if the transition causes spikes on the power line
when ____.
a. adding another three pole contactor and resistors
b. the motor changes from wye to delta
c. voltage reducing equipment is connected
d. an on-delay timer has been added to the control circuit
Name: Class: Date:
Unit 29 Automatic Starters for Star-Delta Motors