VA rating?

Discussion in 'General Electronics Discussion' started by Arnak, Aug 6, 2011.

1. Arnak

22
0
Apr 1, 2011
Hi,

I would like to know how to calculate the VA rating of a transformer and to perform the revers calculation.

The transformer in question is a 240vac input with 2x 6vac outputs.

The VA rating is 6VA, but what does that work out to in Amps available?

I had understood that the VA rating is calculated by the secondary voltage x the secondary amperage is that correct?

Does the calculation include the 2 secondary windings or just use one x 6vac?

My calculation gives 1amp but that seems very high for a 6VA.

Any advice would be great thanks.

Martin

2. duke37

5,364
769
Jan 9, 2011
The 6VA will be the total input, so 1A output split into two secondarys i.e.500mA each.
Nos da.

3. Arnak

22
0
Apr 1, 2011
VA Rating calculation.

Hi TBennettcc,

Thank you for the URL's.

I did have a look at them, one of them was too complex for me to fully understand.

However I did not see the actual calculation anywhere that differed from my understanding.

If you wouldn't mind, could you please take a look at this transformer and see what you believe the amperage would be?

http://www.rapidonline.com/Electric...rs/Chassis-mains-transformer/82716/kw/88-3710

What confuses me is that I have seen other transformers with a higher VA rating that do not appear to have such a high amperage rating.

All I need is a transformer to supply 12vac at 450ma, so I have assumed that I can series link the 2 x 6vac secondaries together to get 12vac @ 450ma max current.

Thanks,

Martin

4. Arnak

22
0
Apr 1, 2011
VA Rating calculation.

Hi Duke,

Aha!

A light dawns...

I get it now, thanks very much.

Martin