Understand the duty terms
| Term | Typical meaning | Important note |
|---|---|---|
| Standby power | Emergency power during a normal supply failure. | Usually limited hours and not intended as a permanent daily supply. |
| Prime power | The generator is a main supply for variable loads within the stated rating. | Maintenance, average load and annual-hour limits may apply. |
| Continuous power | A stated constant load for extended operation under specified conditions. | Only claim this when the manufacturer documentation supports it. |
Different manufacturers may use rating terms differently. Always read the exact model data sheet and manual instead of relying on one word in an advertisement.
Appearance does not decide the duty
- A silent enclosure reduces noise but can still overheat if airflow is blocked.
- A large fuel tank increases time between refuelling but does not extend the oil-service interval.
- Water cooling can support larger or longer-duty systems, but the complete engine and generator rating still controls.
- An air-cooled generator may run for extended periods within its approved load and maintenance rules, but many small models are intended mainly for backup or intermittent use.
Checks for long or 24-hour operation
- Confirm the model's prime or continuous rating, not only maximum output.
- Calculate average load, motor starts, peak load and expected operating hours.
- Plan safe refuelling, oil checks, filter service and inspection shutdowns.
- Provide ventilation, weather protection, exhaust clearance and access for maintenance.
- For critical service, consider two generators or another backup source so one unit can stop for maintenance.
Even a continuous-rated generator must stop sometimes
Need help with your actual equipment?
Send the equipment nameplates, your location and the loads that must run together.