Marathon — Synchronizing
Operation · paralleling generator sets
From a Marathon service manual — check it applies to your exact model before use.
Before you start
- If an attempt is made to parallel generators which have opposite phase sequence, extremely large currents will be generated which may be injurious to equipment and dangerous to personnel.
Procedure
- Make sure both main switches, breakers or contactors are open.
- Start both sets and adjust the frequency without load by adjusting governor controls.
- Adjust both sets to the same voltage.
- Put both synchronizing switches in the on position.
- Close the circuit breaker on one of the sets.
- The synchronizing lamps will flash at a frequency depending on the difference in speeds.
- Adjust the speed of the unit whose breaker is open until the lamps flash about once every two seconds.
- When the lamps are dark, close the set main breaker.
Source: Marathon service manual. Steps and values are as documented; always cross-check against the official manual and any later revisions for your exact serial number before servicing.