Correct option is A
A synchroscope is the device used to measure the phase difference between the voltage generated by a synchronous alternator and the grid voltage. It also measures the frequency difference between the two systems.
A synchroscope works on the principle of an AC motor. It has a pointer that rotates on a dial, and the direction of rotation indicates the speed of the machine:
· Anticlockwise: The machine is running slower
· Clockwise: The machine is running fast
· Vertically upwards: The speed is correct
Connecting two unsynchronized AC power systems can cause high currents to flow, which can damage equipment.
