Transformer labeling - VA rating (noob question)

SilverLaker · 1st December 2004, 06:44 AM

Couldn't find an answer to this by searching, so I hope someone might be able to give me an answer.

If a transformer is labeled as (for example) 25 V.C.T. @ 2 A, is there a way to deduce the VA rating from that information?

I found a formula on the web as follows:

WATTS = VDC x IDC (output)
VA = 1.4 x ( WATTS + 2 IDC* )

Which would make my example transformer:

WATTS = 25 x 2 = 50 W
VA = 1.4 x (50 + 2 x 2) = 75.6 VA ????

Am I on the right track with this? Or is there no way to find the VA rating from the label i mentioned?

I haven't seen the transformers in question in person, got the information from the website of my local electronics surplus store. So there may be a VA rating labeled on the transformers as AFAIK.
Just curious if that information is sufficient to figure it out...

Grateful for any help.

falcott · 1st December 2004, 07:38 AM

VA = V x A

Therefore, 25V x 2A = 50VA.

SilverLaker · 2nd December 2004, 06:08 AM

thanks falcott, I thought of that, but didn't believe it would be that simple.

Not quite enough for one channel in a GC then...

I appreciate the clarification.

1st December 2004, 06:44 AM	#1
SilverLaker diyAudio Member Join Date: Nov 2004 Location: Los Angeles	Transformer labeling - VA rating (noob question) Couldn't find an answer to this by searching, so I hope someone might be able to give me an answer. If a transformer is labeled as (for example) 25 V.C.T. @ 2 A, is there a way to deduce the VA rating from that information? I found a formula on the web as follows: WATTS = VDC x IDC (output) VA = 1.4 x ( WATTS + 2 IDC* ) Which would make my example transformer: WATTS = 25 x 2 = 50 W VA = 1.4 x (50 + 2 x 2) = 75.6 VA ???? Am I on the right track with this? Or is there no way to find the VA rating from the label i mentioned? I haven't seen the transformers in question in person, got the information from the website of my local electronics surplus store. So there may be a VA rating labeled on the transformers as AFAIK. Just curious if that information is sufficient to figure it out... Grateful for any help.

1st December 2004, 07:38 AM	#2
falcott diyAudio Member Join Date: Jul 2004 Location: Wherever I hang my hat...	VA = V x A Therefore, 25V x 2A = 50VA. __________________ "Everything should be made as simple as possible, but not simpler." - Einstein

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2nd December 2004, 06:08 AM	#3
SilverLaker diyAudio Member Join Date: Nov 2004 Location: Los Angeles	thanks falcott, I thought of that, but didn't believe it would be that simple. Not quite enough for one channel in a GC then... I appreciate the clarification.

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