Can a toroid be reversed?

[leadbelly]

I have a toroid with 2 115V primaries and 1 115V secondary. Can I wire it with the secondary connected to the AC line, just as if it were an EI transformer? It is rated 50/60 Hz if that makes a difference.

[richie00boy]

The primary may be thermally fused, you will probably miss out on this protection if you use it the other way round. It's probably not legal either...

[AndrewT]

Hi,
for use in a 115Vac country it sounds like a 1:1 transformer.
reversing it is certainly feasible.
But besides the problem Richie has pointed out, the primary is usually wrapped first and then insulated, the secondary is usually wrapped on top and insulated.

When done this way it is very difficult to physically damgae the primary.
Reversing it brings the primary to the outside and thus susceptible to damage.

I did strip down an Avel transformer to find they had wound it inside out. I cannot understand why!!

[mpmarino]

I am currently using a 115v secondary/32v primary toroid in my KSA50. It is a specialty item that is spec'd as such. The 115v tap is wired over the 32v taps. I'm not recommending it for the reasons above - but reversing should work fine.

[star882]

Originally posted by leadbelly
I have a toroid with 2 115V primaries and 1 115V secondary. Can I wire it with the secondary connected to the AC line, just as if it were an EI transformer? It is rated 50/60 Hz if that makes a difference.

Why would you use it backwards?
I suppose it's OK if you use a fuse in series. And handle it carefully to avoid damaging it.

The primary handles more power than the secondary so it would make some sense to put it on the outside to allow it to dissipate heat. But that shouldn't make too much of a difference.

[AndrewT]

Hi,
110/120 input and a dual 110/120-0 + 110/120-0 output.

In reverse the voltage is likely to be about 4% to 10% low due to the turns ratio being about 1:1.04 or more.