Indian genset builders cover almost the whole range, from small portable sets of a few kVA to large industrial sets well above 1,000 kVA. Gujarat builders are strongest in the small and middle bands, while the largest sets are usually built around engines from major Indian engine plants.
The kVA number alone tells you little. You need to know what rating it is, at what power factor, and under what site conditions.
kVA and kW are not the same
kVA is apparent power, and kW is real power. The two are linked by power factor. Most gensets are rated at a power factor of 0.8, so a 100 kVA set delivers 80 kW of real power. The engine must supply that real power plus the alternator's losses.
If your load has a poor power factor, such as many motors starting at once, you may need more kVA than the kW figure suggests. Motor starting is the most common reason a set turns out too small.
Rating types under ISO 8528-1
ISO 8528-1 defines the main ways to rate a genset. Ask which one the quoted kVA follows:
- Continuous operating power: the set can run at this load without limit of hours.
- Prime running power: the set can run unlimited hours at a variable load whose average stays below the rating.
- Limited-time running power: the set can run at this load only for a limited number of hours a year.
- Emergency standby power: the set supplies power during a grid outage for limited hours, with no overload allowed.
Compare like with like
Standby ratings are higher than prime ratings for the same set, because the set runs only for limited hours. A set sold as 100 kVA standby may be closer to 90 kVA prime. If one builder quotes standby and another quotes prime, the cheaper-looking set may simply be smaller.
Ask each builder to state the prime rating, the standby rating and the engine model behind both. Then check the engine maker's own data sheet for that engine at your speed. If the engine's power does not support the claimed kVA, the rating is optimistic.
Derating for your site
Engine power falls as altitude and air temperature rise. A set rated at standard reference conditions can lose a meaningful share of its output on a hot site or at altitude. Ask the builder for a derating figure for your site, based on the engine maker's data.
For how these choices fit into a full specification, see how to write a genset specification. For the range of builders in the state, see gensets made in Gujarat.
Next step
We check that the rating on the nameplate matches the engine and alternator inside, and witness load tests before shipment. To size sets for your market, book a free sourcing review.