Sketch and describe about Synchroscope.

Synchroscope is used to parallel the incoming generator with running generator or bus bar. By this synchroscope two phases of incoming generator can be match with same two phases of switchboard.

The Synchroscope is a small motor with coils which have 2 poles. Poles are connected across red and yellow phases of the incoming generator. At the same time, armature windings supplied from red & yellow switchboard bus-bars. 

 

In armature circuit incorporates a resistance and an inductance coil in parallel. The inductance has the effect of delaying current flow through itself by 90 degree relative to current in the resistance. The dual currents are fed to armature winding via slip rings and produce there a magnetic field.

Here, the incoming gen polarity of the poles will alternate north/south with changes in red and yellow phases. Now rotating magnetic field react with the poles and trying to turning the rotor clockwise or anticlockwise. It depends on the incoming generator is running too fast or too slow. Normally incoming generator speed should be slightly fast than running on and pointer turning slowly clockwise. The circuit breaker is closed just before the pointer reaches the 12 O'clock position. Which indicate that the phase of the incoming generator and phase of the switchboard bus-bars is same.