why generators are rated in KVA?

Answer 1

he term KVA comes from volts x amps ( VA ) which gives a notional value of watts. However this is only true for items that have zero power factor such as heating elements, power supplies etc.

The rating of a generator is based on a power factor of zero, which motors don't have. so you might find a 2KW motor could not run off a 2KW generator.

but not all,u may find dc generator take it as a specific case where the rating is always given in KW.

But in case of transformers cu loss depends on current ans iron loss on voltage so the total loss is dependent on the product of vol and amperes,it is expressed in KVA.But here power factor ie the cosine of the angle b2in them is not taken into consideration.
KW=KVA* power factor

in case of alternators the theroy is somewhat same,in induction gen too,so they are given by KVA

Answer 2

kVA is volts times amps (x 1000). This equals kW only in purely resistive loads such as heaters, lights etc.

Motors have a lagging power factor which means that their kVA requirement will be higher than the kW rating.

Therefore its kVA that you need to keep below the generators rating or it trips out or worse still, burns the windings.

Answer 3

KVA or KiloVoltAmps is a measurement of apparent power in thousands. Apparent power is the theoretical power of the generator. Since the generator is mechanical and it also has electrical losses in generation, one needs to know the theoretical power in order to determine how much horsepower is needed to turn it. The device used to turn the generator must have enough horsepower to overcome the electrical and mechanical losses, not just the KW or KiloWatt output of the generator. Remember we are transforming one energy source to another and losses must be accounted for.

Answer 4

To add on to the conversation about why a 2KVA motor won't run off of a 2 KVA generator. After you determine the pf of the machine you use KVAR to express the actual load. The R stands for reactive.

Answer 5

Transformer and genrator PF depends on the nature of connected load ( Motor ), But motor has its own fixed Power factor.

Therefore Transformer and genrator capacity shown in KVA (Without PF ) and motor Capacity shows in Kw ( with power factor ) .

https://www.electrikals.com/products/r/generator-sets?cid=694&page=1&pagesize=15

Answer 6

generators are the device which generates current and current is measured using the unit called Ampere. not sure of volts but current generated and supplied is seen for every volts per ampere. Since it is in large amount , we have k i.e, Kilo

Answer 7

because that is a metric unit for electrical power.