Generac GEM750 / MD750 - GEM — Typical Operational Sequence
Operation · PowerManager control system (PM-SC / PM-PC)
For the Generac GEM750 / MD750 - GEM, from the Generac manual.
Applies to: Generac GEM750, Generac MD750 - GEM, Generac 12.0 DTA engine
Procedure
- A transfer switch in the PM-DCP configuration detects a utility failure and issues a start command.
- The command goes to the PM-SC which issues a start command to the PM-PCs.
- Each generator will start on its own.
- The first generator attaining rated frequency and voltage connects to the common generator bus via the switching mechanism.
- The second generator synchronizes and closes into the bus via the switching mechanism.
- When both gensets are paralleled to the bus, the PM-SC signals transfer switches to transfer to the load in up to 3 programmed steps.
- If an NFPA 10 second start requirement exists, the first unit connects to the bus so a separate emergency transfer switch transfers to the NFPA load.
- If a single generator fails, load shed contacts disconnect selected non critical loads.
- If load conditions are reduced (night time operation), one generator can be programmed off line (optional).
- When utility returns, PM-SC transfers loads back to utility and commands individual PM-PCs to disconnect from the bus.
- Each PM-PC operates its generator for the cool-down period and then issues a shutdown command.
Source: Generac 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.