Page 255 - Electrical Equipment Handbook _ Troubleshooting and Maintenance

SYNCHRONOUS GENERATORS

12.18 CHAPTER TWELVE

FIGURE 12.21 Steps taken to synchronize an incoming ac
generator to the supply system. (a) Existing system voltage
wave. (One phase only shown.) (b) Machine voltage wave
shown dotted. Out of phase and frequency. Being built up to
equal the system max. volts by adjustment of field rheostat.
(c) Machine voltage now equal to system. Voltage waves out of
phase but frequency being increased by increasing speed of prime
mover. (d) Machine voltage now equal to system, in phase and
with equal frequency. Synchroscope shows 12 o’clock. Switch
can now be closed.

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