Question: The purpose of providing dummy coils in a generator is__________________?

• 1. to reduce eddy current losses
• 2. to enhance flux density
• 3. to amplify voltage
• 4. to provide mechanical balance for the rotor

Question: If residual magnetism is present in a D.C. generator, the induced e.m.f. at zero speed will be____________?

• 1. zero
• 2. small
• 3. the same as rated voltage
• 4. high

Question: Armature reaction in a generator results in_____________?

• 1. demagnetisation of leading pole tip and magnetisation of trailing pole tip
• 2. demagnetisation of trailing pole tip and magnetisation of leading pole tip
• 3. damagnetising the center of all poles
• 4. magnetising the center of all poles

Question: Following energized winding of a D.C. machine should not be opened as it would produce high inductive voltage which may be dangerous to personnel and may cause its own insulation failure.

• 1. Series field
• 2. Compensating field
• 3. Inter pole field
• 4. Shunt field

Question: Which generator would you prefer for feeding long D.C. transmission lines ?

• 1. Series generator
• 2. Shunt generator
• 3. Over compound generator
• 4. Flat compound generator

Question: In a D.C. generator the critical resistance can be increased by_____________?

• 1. increasing its field resistance
• 2. decreasing its field resistance
• 3. increasing its speed
• 4. decreasing its speed

Question: In a D.C. generator:___________________?

• 1. external resistance = internal char-acteristic – armature reaction
• 2. internal characteristic = magnetisation characteristic – ohmic drop
• 3. external characteristic = magnetisation characteristic – ohmic drop – armature reaction
• 4. magnetisation characteristic = external characteristic

Question: The number of armature parallel paths in a two-pole D.C. generator having duplex lap winding is______________?

• 1. 2
• 2. 4
• 3. 6
• 4. 8

Question: Wave winding is composed of_______________?

• 1. any even number of conductors
• 2. any odd number of conductors
• 3. that even number which is exact multiple of poles + 2
• 4. that even number which is exact multiple of poles

Question: For both lap and wave windings, there are as many commutator bars as the number of_____________?

• 1. slots
• 2. armature conductors
• 3. winding elements
• 4. poles