dc machine Quiz Practice Quiz | DC Machines

Q: In a DC machine, the armature winding resistance primarily affects which performance characteristic?

Voltage regulation — Armature resistance causes voltage drop, affecting the terminal voltage and hence, voltage regulation.

Q: What is the primary function of compensating windings in a DC machine?

To reduce armature reaction — Compensating windings counteract the demagnetizing and cross-magnetizing effects of armature reaction.

Q: How does increasing the number of poles affect the generated EMF in a DC machine, assuming all other parameters remain constant?

Increases the EMF linearly — Generated EMF is directly proportional to the number of poles (P), assuming constant flux per pole and speed.

Q: In a DC shunt motor, if the field winding suddenly opens while the motor is running under load, what is the most likely outcome?

The motor speed will increase dramatically, potentially causing damage. — Loss of field flux causes the motor to accelerate uncontrollably due to inverse proportionality between speed and flux.

Q: What is the purpose of interpoles (commutating poles) in a DC machine?

To improve commutation by neutralizing the reactance voltage. — Interpoles are designed to neutralize the voltage induced in the armature coils undergoing commutation, improving sparkless commutation.

Question 1 of 5

In a DC machine, the armature winding resistance primarily affects which performance characteristic?

Armature resistance causes voltage drop, affecting the terminal voltage and hence, voltage regulation.

Question 2 of 5

What is the primary function of compensating windings in a DC machine?

Compensating windings counteract the demagnetizing and cross-magnetizing effects of armature reaction.

Question 3 of 5

How does increasing the number of poles affect the generated EMF in a DC machine, assuming all other parameters remain constant?

Generated EMF is directly proportional to the number of poles (P), assuming constant flux per pole and speed.

Question 4 of 5

In a DC shunt motor, if the field winding suddenly opens while the motor is running under load, what is the most likely outcome?

Loss of field flux causes the motor to accelerate uncontrollably due to inverse proportionality between speed and flux.

Question 5 of 5

What is the purpose of interpoles (commutating poles) in a DC machine?

Interpoles are designed to neutralize the voltage induced in the armature coils undergoing commutation, improving sparkless commutation.

dc machine Quiz