Ringing Transformer from overloading or overdriving

[Simmon]

When you hear a transformer ringing sound or sounds from a transformer how do you know if it's from overloading the secondary or overdriving the primary? or what else can it be?

When overloading a transformer it makes rings sounds
When overdriving the input it makes ringing sounds

What test can i do with the O-scope to know if the transformer is overdriven or overloaded?

What else would cause ringing in transformer?

 

[(*steve*)]

It all depends.

Sometimes transformers can make noises when used within their specs. They can also be totally silent when grossly overloaded.

The sound s are caused (generally) by changes in magnetic flux causing parts to move. Another cause is heating which can cause sounds. Or even the sound of venting gasses or liquids as insulation fails...

 

[KrisBlueNZ]

In addition to what Steve said (which I totally agree with). You can detect core saturation by monitoring the primary current - either insert a low-value non-inductive resistor in the return line to 0V and scope the voltage across it, or use a current probe on the scope. If you see the current suddenly start to increase rapidly at some point in the drive waveform, that's because the core is saturating. (Unless it's an artefact of something strange happening at the secondary load.)

Overloaded transformers will get warm or hot. I think that might be the only way to tell (I don't know that much about transformers).