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-   -   Xentek 5kva isolation transformer runs hot! (http://www.diyaudio.com/forums/power-supplies/175191-xentek-5kva-isolation-transformer-runs-hot.html)

lawname 11th October 2010 05:05 PM

Xentek 5kva isolation transformer runs hot!
 
I purchased a Xentek 5Kva isolation transformer from ebay. I configured this transformer as 120v in and 120v out. It runs hot! I cannot stand it when I hold my hand on it after 45 minutes of use. Any ideas?

bob91343 11th October 2010 08:15 PM

I assume you are testing it with no load. If it runs hot with no load, the reason could be the core is saturating or there is a shorted turn or more.

Put it on an inductance bridge and then short the secondary to see how much the inductance changes. A ratio of 1000 to 1 is not unusual and means you don't have a shorted turn. A slight change means a shorted turn.

If you don't have a shorted turn then the core is saturating. Recheck your connections to make sure you are really applying 120 V to a 120 V winding. Try connecting it to a higher voltage tap if you have one.

AndrewT 12th October 2010 11:15 AM

Quote:

Originally Posted by bob91343 (Post 2329481)
Put it on an inductance bridge and then short the secondary to see how much the inductance changes. A ratio of 1000 to 1 is not unusual and means you don't have a shorted turn. A slight change means a shorted turn.

is there a compendium of these troubleshooting titbits?

AJT 12th October 2010 11:28 AM

how hot is hot? did you measure actual temperature rise?

how heavy is your traffo?

cores used for traffos have a definite core loss stated in watts per pound of core, these together with magnetizing and no load primary current contribute to a hot transformer......

lawname 12th October 2010 11:57 PM

Thanks for your reply! I have 120V receptacle on the output. I tried my Coda 2.5 class A power amplifier. It runs hot with or without the amplifier. I don't have the knowledge to try the way you mentioned at your reply. I connected it 120v in and out based on the diagram at the panel of this transformer. I will attach some pics. Maybe it will help an expert to understand the situation.

lawname 13th October 2010 12:26 AM

Xentek 5kva isolation transformer runs hot!
 
4 Attachment(s)
Many thanks for all your replies! I attached some pics. I think this will help you experts here understand the situation better. I followed the diagram at the panel of this transformer for 120v in and out.

I don't have any knowledge regarding this transformer other than that. I didn't measure the temperature. I touched it with my hand and couldn't hold it after its 45 minutes running with or without my coda class A amplifier.

Thanks, again. Jim

lawname 13th October 2010 12:30 AM

This transformer weighs around 120 lbs.

lms 13th October 2010 12:32 AM

to dramatically reduce the core loss connect the transformer as 240v to 240v and use on 120v. You will have a cool running 2.5kw isolation transformer and save up to 50w of power at idle

Speedskater 13th October 2010 12:39 AM

If I remember correctly a Model 5410 weighs about 42 pounds. This puppy has 0.005 pF leakage capacitance. I'll try to find the terminal wiring schematic.

lawname 13th October 2010 12:58 AM

Quote:

Originally Posted by lawname (Post 2330845)
Many thanks for all your replies! I attached some pics. I think this will help you experts here understand the situation better. I followed the diagram at the panel of this transformer for 120v in and out.

I don't have any knowledge regarding this transformer other than that. I didn't measure the temperature. I touched it with my hand and couldn't hold it after its 45 minutes running with or without my coda class A amplifier.

Thanks, again. Jim

Note: The first two photos are from my 1kva Xentek. They have same diagram at the panel.


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