Xentek 5kva isolation transformer runs hot!

bob91343

Member
2010-03-11 10:43 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.
 

lawname

Member
2010-10-11 2:01 am
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

Member
2010-10-11 2:01 am
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
 

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lawname

Member
2010-10-11 2:01 am
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.
 

bob91343

Member
2010-03-11 10:43 pm
That is one big transformer! I can't imagine why you'd want to use such a thing.

If it runs hot it must have a shorted turn. If you have a wattmeter, measure the power draw with no load. Obviously it's high or you wouldn't have that much heat.

I submit that the thing is defective.
 

bob91343

Member
2010-03-11 10:43 pm
AndrewT, looking for a compendium of troubleshooting tidbits - well just ask me. I have more information in my head than even I can believe. Seriously, these things require a certain talent to invent. For instance, I invented (I am sure I'm not the first) a method of discovering where a break is in a shielded cable. It's usually at one end but my method finds it without cutting or piercing, within an inch or so.

It also helps that I have a degree in Electrical Engineering, have been a radio amateur for over 60 years, and owned an electronics repair shop for many years.