Heating in isolation transformer

[jmacion]

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We have a 1800W isolation transformer that is overheating in 2 hours even though the measured VA is about 1800W.
Yes we have plenty of cooling on it, it just heats up very quickly.

We know that there is noise generated from the power factor correction algorithm on the amplifier on the transformer load side.
We believe the transformer is able to filter much of the noise.
The vendor of the power amplifier asked us to use the transformer as they say it has helped other customers get UL approval by reducing noise put back into the mains (i think it was conducted emissions).

Does the energy from the noise turn to heat in the transformer? If so, how much?

I dont understand enough of the magnetics theory.
Also, what about inefficiency of transformer, its typically 90% but do the losses go toward heat?

thanks

 

[wayne440]

Please define "overheating". Do you know the temperature rise rating of the transformer?

 

[jmacion]

overheating is thermal shutdown at 110c thermal fuse within ISO
we measure around 48C external

 

[FacEngrPE]

Not enough information, guessing to fill in a gap. You indicate the isolation transformer is intended to filter out "Noise" from an "amplifier".
You may need a k factor transformer selected for your particular conditions. Guide to transformer harmonics and k-factor

 

[iop95]

What kind of controller PFC use?
Some PFC schematics and/or loads may inject a DC component on grid/transformer that modify saturation limits.

 

[jmacion]

thank you all

FacEngrPE has the answer I was hoping for in the link

Higher frequency harmonics can have adverse effects on a transformer’s core as well. In an AC circuit, the polarity of the magnetizing current in the core switches back and forth with the direction of the applied current. In other words, the rate at which the magnetizing current in the core changes polarity is driven by the frequency of the applied current. If the frequency of a standard AC power supply is doubled from 60 Hz to 120 Hz, then the magnetizing current in the core will go from switching polarity 60 times per second to 120 times per second. The higher the rate of change in the magnetizing current, the greater the amount of heat loss in the core. These additional losses are known as hysteresis losses.