Answer / md0711

All electrical devices that supply power are usually rated in kVA. but generator put supply power in kVA because KVA is "apparent power" which does not take an account of power factor and KW is "true power". They generated own power factor
like :
VA = E X I
W = E X I COS PHI

Answer / shelleymuston

All electrical devices that supply power are usually rated in kVA. This includes transformers, UPS's & the like.

Simply put, the difference between kVA & kW is that kVA is "Apparent Power", which does not take into account the Power Factor & kW is "True Power" . See the below equations:

VA = E x I
W = E x I x Cos phi

The above equations are only for single phase.

When a manufacturer makes a transformer, generator, UPS etc, they have no idea of the type of load that will be used & consequently can only rate the device according to its maximum current output that the conductors can safely carry (at untiy Power Factor) & the insulation rating of the conductors (voltage & temperature).

Answer / dave mudra

The power √3 VL IL Cos φ delivered by the alternator for the same value of current, depends upon p.f. (Power Factor=Cos φ) of the load. But the alternator conductors are calculated for a definite current and the insulation at magnetic system are designed for a definite voltage independent of p.f. (Cos φ) of the load. For this reason apparent power measured in kVA is regarded as the rated power of the alternator.

I have a question, I visit 01 site and face a problem, there is 2.5 ton Air Con working, when air con compressor is running at that time rectifier voltages are increasing upto 290-295 v and rectifier is giving main high alarm (rectifier is APC single phase), before starting compressor rectifier voltages was 230v. when air con is going off rectifier voltages are decreasing smoothly at its actual voltages 230v. Load on Genset phases is this: Red-13.5 amp AC (Air Con load), Yellow-1.7 amp AC (BTS lights etc.) and Blew-4 amp AC (telecom system load), Genset phase to phase and neutral to phase voltages are also ok. These are 10 sites having same system and same rectifier APC brand at every site 02 genset are working but the problem is same at all these 10 sites. What will be the reason behind???

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