[Top] [All Lists]

Re: [Amps] questions on my tranformer test

Subject: Re: [Amps] questions on my tranformer test
From: Steve Thompson <>
Date: Sun, 12 Jun 2005 21:14:21 +0100
List-post: <>
kenw2dtc wrote:
> Hi,
> I'm trying to figure out the current rating of a plate transformer.  This is 
> my test setup:
> Questions:
> 1.  Is this a valid way to find the secondary current capability?
I think so. Remember that what you have measured is the rms secondary 
current - which defines the heating effect. The dc current you can end 
up with depends on several factors but is likely to be 30-50% of the rms 
value. Best check is with the Duncan Amps PSU designer which will tell 
you the rms current in the winding for different configurations, 
capacitor values and load resistances, but you will have to edit the 
rectifiers file to create a diode with enough PIV.

It's also worth checking how much it heats up with full primary volts 
and o/c secondary, and derate the secondary current if necessary. I have 
transformers that run cold like that, and others with noticeable iron loss.

> 2.  Is the internal temperature of 180 degrees F too high for a transformer 
> under load for 5 hours?

I'll pass on that one - if you run it at 2.9A rms but, say, 50% duty 
cycle then the temperature rise will be much lower.
> 3.  Is there a problem running this center tapped beast in a full wave 
> capacitive input configuration?
Depends on the insulation between the centre tap and the frame. If the 
designer assumed the ct was going to be ground, it might not be rated 
for it. I've lost a transformer that way.

Amps mailing list

<Prev in Thread] Current Thread [Next in Thread>