Size of Generator for (2) 500 KVA Transformers

[nemoid]

Very, very dumb question, but I haven't done this in a while and I am blanking.

I have (2) 500 KVA transformers. I want to provide a generator to back up both transformers (each will be provided with a manual transfer switch). What is the size of the generator?

2*500*.8= 800kW?

 

[Smart $]

The necessary generator output rating under the NEC is determined by the calculated load, which could be substantially less than the sum of transformer kVA ratings.

 

[GoldDigger]

Just make sure that the generator can handle the transformer inrush from random switching or else provide for a phase-controlled transfer.

 

[ron]

Very, very dumb question, but I haven't done this in a while and I am blanking.

I have (2) 500 KVA transformers. I want to provide a generator to back up both transformers (each will be provided with a manual transfer switch). What is the size of the generator?

2*500*.8= 800kW?

That will work from a simplistic method.

Consider the inrush of the transformers and whether the load is significantly less than 1000kVA or very high power factor. If the load is close to 1000kVA and a high power factor >80%, then you need a bigger gen.

 

[nizak]

If this is an established business, POCO will have history of monthly useage. Many times that info is more than sufficient to determine back up/stand by power requirements.