KW or KVA

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Old 08-26-15, 11:23 PM
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KW or KVA

So, I have an ACCU with 9.2 KVA. The electrical characteristics of the ACCU is 4.30 KW, single phase, 230 Volts. The question is what current should I use for sizing the breaker - the one from KVA or the one from KW.

I = 9.2 KVA/230 = 40 A

I = 4.3 KW/230 = 18.7 A
 
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Old 08-27-15, 07:10 AM
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You have to use KVA for sizing the wiring and breaker.
 
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Old 08-27-15, 05:54 PM
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What is ACCU? Sorry for asking a dumb question!
Geo
 
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Old 08-27-15, 07:30 PM
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It's Ok now. I have used KVA to buy the breakers needed.

For your information, ACCU is Air Cooled Condensing unit.
 
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Old 08-27-15, 08:44 PM
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engrkira, while you are explaining, another dumb question. Since VA = W, why the difference?

Bud
 
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Old 08-27-15, 09:08 PM
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I have 2 ratings here and I don't know what to use. Maybe you should read again. I know that in a single phase VA = W but then there are 2 ratings presented so I am asking questions. Read First before posting.
 
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Old 08-27-15, 09:21 PM
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"Read First before posting." That isn't a very friendly reply, try again.

I did read and you didn't answer the question, yet you already bought a breaker. The breaker size should protect the wire and the wire and breaker should be large enough to not trip during normal operation.

What size wire did you install?

Bud
 
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Old 08-28-15, 05:51 AM
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Why not just go by the mfg. requirements for wire and breaker size?
Geo
 
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Old 08-28-15, 05:51 AM
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VA only equals watts with resistive loads. The full formula is KVA times Power Factor = KW. When you have inductive (or capacitive) loads like motors and fluorescent lighting, the current and voltage are not in phase. This phase difference is represented by the power factor. Resistive loads have a power factor of 1, but motors and the like will have a smaller power factor.

When you size the wiring for big inductive loads, such as the ACCU, you use the KVA rating because that tells you what the current flowing to the load will be, and it's the current that determines the wire size and breaker size needed.
 
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Old 08-28-15, 05:56 AM
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Thanks CT. My electronics background never had to deal with motors and phase relationships, although I do understand them. Makes sense.

Bud
 
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Old 08-28-15, 05:31 PM
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I'm thinking the ACCU also has electric heat which is why the large difference between KVA and KW.
 
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Old 08-28-15, 06:54 PM
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Nice CT. Good explanation. I have used the KVA by the way.

Bud thanks too and sorry if my words offended you. Didn't mean anything with that.
 
 

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