Rating of DG sets 1

[urjaengrs]

I have observed that normally, low voltage DG sets ratings mentione din kVA and high voltgae DG sets in MW. Can somebody put his input regarding DG sets ratings. Is there any standard for mentioning these ratings? Whether it shall be mentioned in MW ort in MVA? I do agree that all electrical source rating generally to be mentioned in MVA and not in MW. However, valuable inputs are reuired.
In advanse Thank you.

 

[ScottyUK]

Engine power output is measured in Watts or some multiple thereof. Alternator ratings are measured in VA or some multiple thereof. The two are related but not interchangeable; both are required to correctly specify the generator.


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Sometimes I only open my mouth to swap feet...

 

[doehl1]

It is quite common in larger gensets for the alternator to be oversized as related to the mechanical power output of the prime mover, whether this be a turbine or reciprocating engine. This allows the OEM to provide a standardized frame size alternator for various models/options on the base prime mover variety. In addition, it is much more common for larger gensets to be operated in parallel with an infinite bus (utility). In this case, reactive power (VARs) supply, and hence the related kVA becomes less important and kW imported/exported is typically the tariffed quantity. In smaller sets, often these are connected in an island mode with a dedicated load, which has a much more specific kVA requirement.