Power Rating on Toroids w/ Multitaps?

[ccochran]

Provided Link: http://www.partsexpress.com/pe/showdetl.cfm?&DID=7&Partnumber=129-095


When a toroidal transformer has more than one set of output taps, how do you know the VA rating on each.
Take for example:
<A HREF="http://www.partsexpress.com/pe/showd...number=129-095">http://www.partsexpress.com/pe/showd...number=129-095</A>

It has 2x55 and 2x16.2 and 1x14.
The VA rating on it is 350VA

Suppose I only want to use the 2x16.2 to power an amplifier or whatever, would I get the full 350VA out of it, or do you only get the full rating on the "main" output - the 2x55 in this case?

Or a different scenario - suppose you are using all three sets of taps. I'm guess the 350VA would somehow be divided amoung the them.

[hongrn]

There are no specs on this buyout, but if you picked an Avel Linberg toroid, the spec sheet will give you the current for the secondary. See this link, and click on the manufacturer's spec sheet.

<A HREF="http://www.partsexpress.com/pe/showd...number=122-640">http://www.partsexpress.com/pe/showd...number=122-640</A>

[jonpike]

> When a toroidal transformer has more than
> one set of output taps, how do you know the
> VA rating on each.
> Take for example:
>
> <A HREF="http://www.partsexpress.com/pe/showd...number=129-095">http://www.partsexpress.com/pe/showd...number=129-095</A>
> It has 2x55 and 2x16.2 and 1x14.
> The VA rating on it is 350VA

> Suppose I only want to use the 2x16.2 to
> power an amplifier or whatever, would I get
> the full 350VA out of it, or do you only get
> the full rating on the "main"
> output - the 2x55 in this case?

The way to look at is is, you have a total of 350VA available to you, due to the capacity of the core. Theoretically, ANY winding could deliver up to 350 watts.

In the real world though, the various windings might NOT be able to handle that, due to the size of the wire they are wound with only being able to handle a certain amount of current before overheating. Say, you have a 5V winding rated for 1A, and try to draw 350W... you'll be trying to pull 70A thru a probably 28ga winding, and the wire will try to glow red... causing smoke, flames, and other transformer annoyments.

If the winding was up to it, you actually COULD do 70 amps @ 5V, without the core overheating...

Hope the extreme examples helped show the issues.
Without actual ratings... about all you can do is try to see the actual winding wire size, (not neccicarily the size of the lead coming out of the transformer) and look up the current rating of that size.

HTH..

Jon