Author Topic: Toroidal transformer - problem at connecting  (Read 201 times)

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Offline mike_mike

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Toroidal transformer - problem at connecting
« on: December 07, 2019, 03:38:19 pm »
Hi, I received a toroidal transformer that had the secondary 2x24V / 100VA with median socket. This secondary has been opened in order to be able to connect in parallel the two 24V windings resulting from the opening of the median socket. Unfortunately, the two windings were connected incorrectly and the transformer was powered this way for a few seconds and it heated up (but not very much). Then it was disconnected from the 230V network.
I checked it, it is functional, both secondary have the voltage of 25.5V with no load when 230V at network.
I checked the primary by measuring with the Ohmmeter and comparing it with another transformer that had the primary winding for the same voltage, and the results were very close.
Also, I also checked using the Ohmmeter the secondary and both had the same resistance.
Then I connected in parallel the 2 secondaries (this time correctly) and I powered the transformer and let it powered for 4 hours and it did not heated up.

Are there any other ways I could figure out whether or not there are or will be any problems with this transformer?
« Last Edit: December 07, 2019, 04:06:40 pm by mike_mike »

Online andy3055

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Re: Toroidal transformer - problem at connecting
« Reply #1 on: December 07, 2019, 05:24:22 pm »
The only test you can do is an insulation test. Between the windings and from windings to the core (if the core is visible anywhere). For that, you will need something like a megger.

Offline Jwillis

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Re: Toroidal transformer - problem at connecting
« Reply #2 on: December 07, 2019, 11:26:14 pm »
You probably connected the secondaries so they were out of phase with each other . Heating of the transformer would be the result . Most transformers can handle a fair amount of heating as long as the shielding on the coils doesn't melt .  Most windings on transformers now use a Polyurethane ,Polyester or Polyimide coating and can stand temperatures from 155C to 180C and Polymides can be higher. That quite a bit of heat. Even 60C can be hard to touch.  If your getting the correct readings when the secondaries are configured properly you should be alright.

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