Overspeed

Why generators show "overspeed": 3 documented causes and brand-specific fixes, compiled across 11 manufacturers.

Governed frequency exceeding 70 Hz will energize SDR relay and shutdown unit. Overspeed shutdown may be caused by governor malfunction/misadjustment or rapid loss of load.

2 brands

Defined as 120% of rated speed for engines rated from 1470 through 2600 rpm, and 110% of rated speed for engines rated from 2800 through 3000 rpm.

1 brand

Clarke: Investigate the cause and make necessary corrections before placing engine back in service. The OVERSPEED RESET BUTTON must be pressed to reset.

Battle Short mode is suspended and a shutdown occurs immediately

1 brand

Affected models

Cummins/Onan 100GGHH Cummins/Onan 1100DFLB Cummins/Onan 1120 DFLC Cummins/Onan 1250DFLC Cummins/Onan 125GGHJ Cummins/Onan 1290DFLE Cummins/Onan 1500DFLE Cummins/Onan 55GGHF Cummins/Onan 60GGHE

Related fault codes

Caterpillar fault codes Cummins/Onan fault codes Doosan fault codes Ford fault codes Generac fault codes Kohler fault codes SDMO fault codes

Common questions

What causes overspeed?

Common causes, most-reported first: Governed frequency exceeding 70 Hz will energize SDR relay and shutdown unit. Overspeed shutdown may be caused by governor malfunction/misadjustment or rapid loss of load.; Defined as 120% of rated speed for engines rated from 1470 through 2600 rpm, and 110% of rated speed for engines rated from 2800 through 3000 rpm.; Battle Short mode is suspended and a shutdown occurs immediately.