possibly confused about transformer

[SQ Kid]

i tried a search, but kind got confused on what i was reading. this is the first time i've had a toroid transformer and dont feel like blowing up a perfectly good piece of equipment, let alone myself.
what i'm confused about is the idea of dual primaries (so it can run 120 or 240). i tested the trans yesturday by having only one set of primaries hooked up and i ended up with 22v on the primaries (2 sets of 22v, one set of 11v). is it a bad thing to only run one set of primaries as opposed to both? will anything be damaged? the voltages i got are perfect for my amp in progress, but i dont want to skip safety just to get what i want.
any help is much appreciated. thanks

[lieven]

as long as you don't put mains on the secundaries, nothing ugly could happen.

If you put 230v on paralleled 115v windings, you'll end up with double output voltage on secundaries.(with of course same VA-rating, i.e. half of amperes mentioned)

!!! on single 115v winding 230v, would say you use only half the primary capacity, so also half the VA-rating, so only 1/4 amperes mentioned for secundary current!!!!

You'll have to connect the primaries in phase (dot-nodot-dot-nodot for series=230v, dot+dot...nodot+nodot in parallel=115v). If it's right on the primary side, you'll have the highest secundary voltage.
Think for normally coded primary wires, its yellow to orange connected for 230v series, blue and brown is mains 230v. (this is the mci transformer I have here in front of me)

use a breaker or fuse!!!!

This is no game!!!

Someone please read and reject or acknowledge.

[SQ Kid]

thanks for the reply. this isnt my first time "playing" with mains power, so i dont plan on blowing myself up anytime soon. this trans was pulled from a piece of electrical test equipment, so its not the typical colors. however, the pcb it was mounted to did list 2 sets of primaries (silk screened on was "0 120 0 120", so i take that as dual primaries, but feel free to correct me). i did hook up one of the "0 120" pairs and then did my secondaries testing. so i guess my question is: will i hurt anything by leaving the other set of primaries unhooked?

[sreten]

In the case in question there is no reason
to leave the other primary unconnected.

Simply wire the two primaries in parallel,
0 to 0 and 120 to 120 and apply voltage.

Your secondary voltages will not change,
you will halve primary resistive losses.

(For 240 volts one 120 is connected to
the other primaries 0 and 240 applied
across the other 0 and 120 connections)

sreten.

[unitgain]

If you leave one primary unhooked, the other primary will have to conduct twice as much current compared to the parallel hook-up. This migt exceed its rating.

[lieven]

You're living in usa, so I think your mains is 120v.

So put primaries in parallel: 0 tied to 0 (=first mains wire) and 120 to 120(=second mains wire). otherwise you use only half of the primary capacity. Compare it with two fuses you put in parallel: double current capacity versus a single one.

There's no harm in using a single winding, but it would be stupid not using the transformer to it's full ratings.

[Bob2]

http://sound.westhost.com/psu-wiring.htm

Give this a read, might help you out.

[johnnyx]

Be reassured that if you connect the primaries in parallel and one is out of phase with the other, you won't damage anything. The primary fluxes will cancel, so the output voltages will be very low. If this happens, reverse the connections to one of them, and all should be well.