Transformer Amps

[ronsimpson]

For power design (buildings), 80% is a safe maximum number. Now, for small transformers I don't know what the percentage is.

Robert

The transformer power rating is with a resistive load. If you use diodes and a capacitor to make DC then the transformer should be de-rated to 50%. Because of the diode/capacitor, current only flows near the peak of the sign wave. The current only flows for about 20% of the time and is 5x larger than with a resistive load.

[The Master]

I think ill go with a chassis transformer then. Ill get a much bigger one so i can run more lights from it too.

Thanks for your help. I understand transformers a little better now

[rsocor01]

The transformer power rating is with a resistive load. If you use diodes and a capacitor to make DC then the transformer should be de-rated to 50%. Because of the diode/capacitor, current only flows near the peak of the sign wave. The current only flows for **Databases
about 20% of the time and is 5x larger than with a resistive load.

There are ways of using 100% of the current cycle with diodes and capacitors, so there is no need to "de-rate to 50%". The VA rating is given for RMS values and yes it is for resistive loads. By the way, the power rating of the transformer depends on the maximum Vrms and Irms that the windings can handle at any given time. How much of the sine wave is utilized in the load is irrelevant.

Robert