151Section 8 Decision-Makerr 3500 ControllerTP-6953 7/19
8.7 Synchronizing Test
Synchronizing is the action of matching the RMS
voltage amplitude, cycle frequency and phase of the
generator with the paralleling bus. The paralleling logic
contains a synchronizer which controls the engine
speed and voltage regulator RMS target to actively
match the frequency, voltage and phase of the
generatortothebus. Thedecisiontoclosethe
paralleling breaker is determined by a synchronism
check function (ANSI relay 25C). The synchronization
check function also includes a dwell timer. If the
frequency, voltage and phase of the generator do not
match the frequency, voltage and phase of the
paralleling bus, closing the generator breaker may
cause damage to the generator due to large circulating
fault currents and mechanical stress generated by the
power angle between the two generators. Follow the
Synchronizing Test below.
Synchronizing Test Sequence
1. Navigate to the Synchronizing Setup Menu
(under the Paralleling Operation Menu).
2. Place the Sync Mode in Auto to OFF.
3. Place the Sync Mode in Run to CHECK.
4. Scroll down until the Phase Difference, Phase
Match P (Proportional) Gain, Phase Match I
(Integral) Gain, Phase Match D (Derivative) Gain,
and Speed Bias are highlighted.
5. Provide the generator set with a start signal
(AUTO-RUN).
6. Allow another generator set to start and close to
bus.
7. Press the AUTO button to start, watch the screen
until the phase difference is at 30 degrees, press
the RUN button to observe sync behavior. Make
any necessary adjustments.
8. Press the AUTO button again, watch the screen
until the phase difference is at 60 degrees, press
the RUN button to observe sync behavior. Make
any necessary adjustments.
9. Repeat steps 7 and 8 above for 30, 60, 90, 120,
150, 180, - 150, - 120, - 90, - 60, - 30, and 0
degrees. Verify minimal overshoot in all cases,.
10. If overshoot is observed, try increasing the P
(Proportional) Gain first.
11. If overshoot does not improve, set the P
(Proportional) Gain to 1.00 and try decreasing the I
(Integral) Gain. If the phase difference does not
stay within the window, it may be necessary to
decrease to P (Proportional) Gain slightly.
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