Engineering · Electrical — Paralleling Generators
Before closing the breaker to parallel an incoming generator with one already on the bus, the incoming machine must match the running bus in voltage, frequency, phase rotation, and:
- AOil pressure
- BExhaust temperature
- CPhase angle (synchronism)✓ Correct
- DFuel rack position
Explanation
A synchroscope (or synchronizing lights) confirms the incoming generator is in phase with the bus. Closing the breaker out of synchronism causes a heavy current surge and severe mechanical shock that can damage the machine and trip protection.
Authority: Modern Marine Engineer's Manual; AC paralleling
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