Understanding Three-Phase Motors

What is a rotating magnetic field?

• A static magnetic field that does not change over time.

• A magnetic field created by permanent magnets only.

• A magnetic field that only exists in a vacuum.

• A rotating magnetic field is a magnetic field that changes direction and magnitude over time, typically produced by alternating currents in coils.

How many phases does a three-phase motor have?

• 5

• 3

• 4

• 2

What creates the rotating magnetic field in a motor?

• The flow of direct current in the rotor.

• The mechanical rotation of the rotor itself.

• The presence of permanent magnets in the stator.

• The interaction of alternating current in the stator windings.

What is torque in a three-phase motor?

• Torque is the amount of current flowing through the motor.

• Torque is the voltage supplied to the motor.

• Torque is the rotational force produced by the electromagnetic interaction in a three-phase motor.

• Torque is the speed of the motor's rotation.

How is torque measured in motors?

• Torque is measured in Newton-meters (Nm) or pound-feet (lb-ft).

• Torque is measured in joules (J)

• Torque is measured in kilograms (kg)

• Torque is measured in watts (W)

What happens to torque when the load increases?

• Torque decreases with an increase in load.

• Torque remains constant regardless of load changes.

• Torque is unaffected by the load applied.

• Torque increases with an increase in load.

What is slip in an induction motor?

• Slip is the difference between synchronous speed and rotor speed, expressed as a percentage.

• Slip is the speed at which the motor operates under full load.

• Slip is the torque produced by the motor at synchronous speed.

• Slip is the maximum speed of the rotor in an induction motor.

How is slip calculated?

• Slip = (Actual Speed - Theoretical Speed) / Theoretical Speed * 100%.

• Slip = Actual Speed / Theoretical Speed * 100%

• Slip = Theoretical Speed - Actual Speed

• Slip = Actual Speed + Theoretical Speed

What does a high slip value indicate?

• Enhanced durability of components.

• Increased efficiency in a mechanical system.

• Improved performance of machinery.

• Inefficiency or excessive wear in a mechanical system.

What are common applications of three-phase motors?

• Solar panels

• Common applications of three-phase motors include pumps, fans, compressors, conveyors, and industrial machinery.

• Household appliances

• Automotive engines