Phase Rotation Tests.

                           Phase Rotation
Observe that the generator phase rotation matches the bus phase rotation. The following procedure may be used to verify that the phase rotation is correct and that the synchroscope in functioning correctly. Refer to Figure for illustration.

Test 1 - This test will verify synchroscope wiring and bus connections leading to the
generator are correct and also verify bus phase rotation.
a. Disconnect generator, secure leads, and isolate.
b. Apply rated voltage to bus and close breaker labeled A on Figure.
c. Connect phase rotation meter as shown and observe rotation.
d. Observe synchroscope, (SYN). Instrument should read 12 o'clock.
e. Open breaker, A, and remove (rack out) from the energized position.

Test 2 - This test will verify that the incoming generator and the bus phase rotation are correct and that the synchroscope is correctly monitoring the incoming
machine vs. the bus source.
a. Reconnect the generator.
b. Bring the generator to rated speed and voltage.
c. Observe phase rotation as shown on phase rotation meter. Phase rotation must be in the same direction as observed in Step 1 above.
d. Observe synchroscope. The hand will rotate clockwise when the generator frequency is higher than that of the bus or counter clockwise if slower than the bus frequency.