how to calculate if transformer will saturate

Easier to test.

John

If V/f is

"mynick"

** The primary saturation voltage for a transformer is proportional to frequency.

So, for a given primary magnetisation current, the voltage doubles if the frequency is doubled.

.... Phil

As John said, test it. Data is often not very useful. My setup:

Function generator -> big stereo amp -> reverse transformer.

The reverse transformer is one of those tube deals, probably more than

50 years old, has a 340V winding. The stereo amp feeds its 12V winding. Now I can vary the frequency from 35Hz to hundreds of Hertz. Luckily this one works well even at 400Hz which allows me to test aircraft circuit designs. A small series resistor has a scope probe hooked to it (careful!) so I can easily see saturation effects.

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Regards, Joerg

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Rough rule of thumb: Keep V / F constant. So a 120V, 60 Hz transformer will work OK with 100V at 50 Hz.

--
Paul Hovnanian  paul@hovnanian.com
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Have gnu, will travel.

Ok, but I guess at around 10,000V at 5kHz ... phhffffft ... tsssss ...

*BAM* :-)

--
SCNR, Joerg

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At lower than designed frequencies?

--
Paul Hovnanian  paul@hovnanian.com
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Have gnu, will travel.

Joerg, I'm a bit confused. At first I thought you were driving the 'transformer under test' (TUT) from the Amp in reverse. And I was going to ask what you used as a high voltage load.

But then I realized that the TUT would hang on the end of your reverse transformer. (I think)

So how 'bout the first mistaken idea. If I don't have a fancy tranny, could I just run the TUT in reverse? Perhaps with light bulbs as load?

George H.

Yep. That's because I am designing some gear for mains voltages that are way different or less stable than in the US. Some designs have to withstand >260V for long periods of time. In lesser developed areas the line frequency fluctuates quite a bit because they use local generators. So I needed something that let me test for all this. Of course during one longer test ... *phut* ... gone was the Wavetek generator so had to buy a new one.

You could do that but not when testing a whole unit with rectifier, switcher and whatnot. As for a load, in order to measure where a transformer saturates you do not need that.

--
Regards, Joerg

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