DC generators are dc machines that convert mechanical energy to dc electrical energy. The DC generator converts mechanical energy into electrical energy using electromagnetic induction principles. This interaction produces an electrical current that can power various devices and machinery. DC generators come in multiple sizes and configurations. In modern industry, however, using DC generators is quite rare. In this post Electrical Engineering Online shares MCQ questions on DC Generator with brief explanatory answers and solutions.
The armature winding in a DC generator is connected to
The armature winding in a DC generator is connected to
- The field winding
- The commutator
- The external load
- A separate source of DC
Answer: 2. The commutator
Explanation: The armature winding in a DC generator is connected to the commutator. The commutator is a rotating electrical switch that allows the connection between the armature coils and the external circuit to be periodically reversed.
The purpose of brushes in a DC generator is to
The purpose of brushes in a DC generator is to:
- Provide mechanical support to the armature
- Control the speed of the generator
- Maintain contact with the commutator
- Change the direction of the magnetic field
Answer: 3. Maintain contact with the commutator
Explanation: The brushes in a DC generator maintain constant contact with the commutator, allowing the transfer of electrical current between the armature coils and the external circuit.
The armature core in a DC generator is typically made of
The armature core in a DC generator is typically made of:
- Copper
- Aluminum
- Soft iron
- Silicon steel
Answer: 4. Silicon steel
Explanation: The armature core in a DC generator is typically made of silicon steel to minimize magnetic losses and provide a low reluctance path for the magnetic flux.
The efficiency of a DC generator is defined as
The efficiency of a DC generator is defined as:
- The ratio of output voltage to input voltage
- The ratio of output power to input power
- The ratio of armature resistance to field resistance
- The ratio of magnetic flux to armature current
Answer: 2. The ratio of output power to input power
Explanation: The efficiency of a DC generator is mathematically expressed as the ratio of the output power (electrical power delivered to the loa4. to the input power (mechanical power supplied to the generator).
The purpose of interpoles in a DC generator is to
The purpose of interpoles in a DC generator is to:
- Increase the output voltage
- Improve commutation
- Reduce armature resistance
- Minimize armature reaction
Answer: 2. Improve commutation
Explanation: Interpoles, also known as commutating poles, are additional small poles placed between the main poles of a DC generator. They produce a demagnetizing effect on the coils undergoing commutation, reducing sparking and improving commutation.
Field coils in DC generators are generally made of
Field coils in DC generators are generally made of:
- Copper
- Mica
- Cast Iron
- Silver
Correct answer: 1. Copper
DC Machines usually have a variety of losses occurring in them. The correct equation that indicates losses in DC Machines is
DC Machines usually have a variety of losses occurring in them. The correct equation that indicates losses in DC Machines is:
- Stray losses = Iron losses + Mechanical losses
- Stray losses = Iron losses – Mechanical losses
- Hysteresis losses = Iron losses * Eddy current losses
- Hysteresis losses = Iron losses + Eddy current losses
Correct answer: 1. Stray losses = Iron losses + Mechanical losses
The type of winding used in welding generator is
The type of winding used in welding generator is:
- Delta winding
- Lap winding
- Wave winding
- Duplex wave winding
Correct answer: 2. Lap winding
The value of full load terminal voltage in the DC generator is
The value of full load terminal voltage in the DC generator is:
- More than the no-load terminal voltage
- Smaller than the no-load terminal voltage
- Same as in the case of no-load terminal voltage
- None of above
Correct answer: 3. Same as in the case of no-load terminal voltage
A DC generator employs compensating windings to
A DC generator employs compensating windings to
- Reduce eddy current losses by providing local short circuits
- Neutralize cross-magnetizing impact of the armature reaction
- Provide a path for cooling air circulation
- All of these
Correct answer: 2. Neutralize cross-magnetizing impact of the armature reaction