The correct answer is: A. Voltage of the incoming generator should be same as that of bus bar.
The other options are incorrect because:
- Option B: The polarity of the incoming generator does not need to be the same as that of the bus bar. As long as the voltages are equal, the generators will synchronize and operate in parallel.
- Option C: The series fields do not need to be run in parallel. In fact, it is not recommended to do so, as this can cause instability in the system.
- Option D: The series fields of all generators do not need to be either on the positive side or negative side of the armature. They can be on either side, as long as the voltages are equal.
In order to parallel two or more DC compound generators, the following steps should be taken:
- Ensure that the voltages of the generators are equal.
- Ensure that the frequencies of the generators are equal.
- Ensure that the polarities of the generators are the same.
- Connect the generators in parallel using a switch.
- Adjust the field current of each generator until the output voltages are equal.
It is important to note that the generators should be synchronized before they are connected in parallel. This can be done by slowly increasing the field current of each generator until the output voltages are equal. Once the generators are synchronized, they can be connected in parallel using a switch.
After the generators are connected in parallel, the field current of each generator should be adjusted until the output voltages are equal. This is necessary to ensure that the generators share the load equally.