3 Phase motors

Slip speed is the difference between:

• standstill & rotor speed

• rotor and stalling speed

• synchronous & rotor speed

• synchronous and standstill speed

The voltage applied to a winding of a Delta connected 3 phase motor is:

• 240V

• 415V

• 240A

• 415A

The voltage applied to a single winding of a star connected motor is;

• 240V

• 240A

• 415V

• 400A

The load type that causes the current to lead the voltage in a Sine wave is:

• Inductive

• Capacitive

• Resistive

• Amphibious

Electric motors operate due to the effect of:

• The visible light spectrum

• Mutual recognition

• Simple circuits

• Mutual induction

If a 3 phase motor has a synchronous speed of 750rpm when connected to a 50Hz supply, determine the number of poles?

• 2

• 8

• 6

• 4

Electric motors consume up to 7 times running current upon

• slowing

• dyno magnetic braking

• start-up

• reduced rpm

Interchanging any two supply lines in a three phase motor will cause

• the motor to stall

• the motor to start

• the motor to stop

• the motor to reverse

The stator field poles are laminated to:

• eddy current gains

• eddy current losses

• primary significance

• dynamic stippling

PTC Thermistors provide the best

• form of over speed protection

• reliable over temp protection

• reliable undertime protection

• accurate temperature reading