A 25 kVA silent genset is a diesel generator set of 25 kilovolt-amperes in a sound-attenuating canopy. At the usual power factor of 0.8 it delivers about 20 kW of real power.
For gensets for construction sites, size the set for the largest motor you must start and for the total running load, then choose a canopy and tank that suit unattended site use.
What does 25 kVA actually give you?
kVA is apparent power. Real power in kW equals kVA times the power factor, so 25 kVA at 0.8 gives 20 kW. Most site loads, such as motors and welders, have a power factor below one, so do not size the set on kW alone.
Check the rating basis. Makers quote standby and prime ratings, and the two differ. Our guide to genset kVA ranges available from India explains what sizes exist. Ask which rating applies at your site temperature and altitude.
How do you size a genset for a construction site?
List every load and note its starting behaviour. A motor draws several times its running current for a moment at start-up. Tower cranes, concrete pumps, hoists and compressors can all need more than their running power.
Work through these steps:
- Add up the running load of everything that will run at the same time.
- Identify the largest motor and ask the alternator maker how much starting load the set can take.
- Allow margin so the set does not run at its limit all day.
- Consider two smaller sets if the load varies a lot, so one can be shut down at light load.
What should the silent canopy and set include?
A silent canopy reduces noise and protects the set from weather. Compare silent and open sets in silent versus open gensets. Ask for the noise level at a stated distance, and for the standard used.
Outdoor generators sold in the EU fall under the Outdoor Noise Directive 2000/14/EC, which sets noise marking requirements. Confirm with your authority or conformity adviser which rules apply to your set.
Specify voltage and frequency, such as 415 V three-phase at 50 Hz, the controller type, the fuel tank size and the engine and alternator make. See how to write a specification for a diesel genset and alternators in Indian gensets.
Think about fuel and access as well. On a site with few visits, a larger tank or an external fuel connection saves refuelling trips, and a lockable canopy with a lifting frame helps when the set is moved with a crane. Ask for the fuel use at stated load steps, so you can plan deliveries.
What should you check before shipping?
Insist on a load test on the actual set. A load bank test at stated steps shows voltage, frequency, temperature and fuel use under load. Record the engine and alternator serial numbers and compare them with the quote.
Check the canopy: door seals, lifting points, cable entries and exhaust. Check the battery, the emergency stop and the earth connection. Ask what the packing is, since sets shipped on open frames can be damaged in transit.
Next step
We shortlist genset builders, witness the load test and inspect the set before loading. Book a free sourcing review with your load list and site conditions.