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# Transformers......

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#### Painandsuffering

##### New Member
Hi its me again thanx to all of your help I passed my chpt 12 test wih an 84 without even talking to my instructor which he says is one of the best chpt 12 scores he's seen. I'm onto chpt 13 now and have hit a bit of a quandry..... What is the maximum source current for a transformer rated at 10kva, 1000/500 60 hz? I have a few other guys working on this question with me that are on the same chapter but they seem to think its 10 but when I put this answer into the practice test it comes up wrong and the answer should be 20 A. I am thinking that I need to do 10k/500 instead of 10k/1k.

What does 1000/500 mean? If it is a 2:1 voltage stepdown, you are correct at 10 amps. But, if it is 2:1 impedance ratio, that is a different animal, and 20 amps is not the answer.

I assume that 1000/500 means that the voltage applied to the primary is 1000 Volt and so the secondary voltage is 500 Volt. If this is true, then the maximum current that you can deliver from the secondary is

10k/500 = 20 Amp (Apparent Power = V x I)

The primary current will be 10k/1k if there is 20 Amp being delivered from the secondary.

Len

You are right, Len, I should have read the post more closely.

I have that problem also Russlk, ie. putting fingers into action before brain.

Len

thanx fellas that was a lot of help and I'm on chapter 14 now RCL Circuits. Its a major pain in the arse since I gotta learn imaginary numbers and stuff like that but it'll be simple the problem is the quality factors Q=Itank/Is and Q=Ztank/Xl what do they mean by the tank part do they mean the main body of it or what me and 3 other people can't figure this out??????????????

The parallel connected L & C is the "tank". The impedance of this circuit is "Ztank" and is resistive at resonance. Xl is the impedance of the inductor at resonance = 2*PI*f*L. I am not sure what Itank and Is are.

Hey guys thanx for all the help I'm out of chapter 14 now and am on my ac/dc final then I gotta do solid state which I will once again be asking for help on. so thanx a lot fellas!

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