Prime-power generating set
A set that is the supply rather than the back-up, running for thousands of hours a year on a site with no usable grid connection. Everything about it is sized for running, not waiting.
Features
- The prime rating carries a 10 % overload allowance for one hour in twelve, and continuous duty without that allowance is a separate, lower rating again.
- Fuel becomes the dominant cost within months, so specific consumption in l/kWh at the expected load is the number that decides the purchase.
- Service intervals arrive on a calendar rather than a plan, so oil, filter and coolant holdings have to be stocked locally from day one.
- Running two smaller sets in rotation usually beats one large set on both fuel and availability, because each runs nearer its efficient load.
- A load bank or dump load is worth specifying where the site load falls below about 30 % of rating for long periods.
- Where the site also has renewable generation, the set's minimum stable load is what limits how much of it can be used.
Specifications
| Figure | Typical range | Unit | Why it matters |
|---|---|---|---|
| Prime output | 100 - 2 250 | kVA | The continuous duty rating. |
| Specific fuel consumption | 0.24 - 0.30 | l/kWh | The figure that dominates total cost of ownership. |
| Minimum recommended load | 30 | % | Below it, running damages the engine. |
| Oil sump capacity | 20 - 180 | l | Drives consumable volumes and disposal arrangements. |