I like the idea of individually set Factors of Safety (FoS), but a random FoS=1.2 for a transformer is probably never achieved for a commercially available 220/240 or 230Vac transformer for domestic use.Due to core tolerances and other factors, I would recommend the transformer be designed to support at least 120% of the maximum voltage you expect to see. In this specific case that is 305 volts.
I like the idea of individually set Factors of Safety (FoS), but a random FoS=1.2 for a transformer is probably never achieved for a commercially available 220/240 or 230Vac transformer for domestic use.
Not quite so Andrew.
I wind power supply transformers with a maximum of 1,2 T at 230 Vac. Mostly not over 1 T.
So there is headroom, and also the transformer will not get hot, and have low strayfields.
As I use c-cores exclusively, I apply a very small airgap to prevent the core from appproaching saturation caused by DC like line pollution, which seems to be pretty common these days. I also apply an electrostatic shield (copper foil) between primary and secondary windings.
A good quality power supply transformer is the basis for a good amplifier.
There was a long discussion about this somewhere. The conclusion was that load current reduces core flux by creating ohmic drop in the primary. Not a huge effect, but if a mains transformer is not saturating off-load then it will not saturate at any load.Saturation in a transformer is independent of the load current.
To clarify one point.
Measuring the Primary current with the secondary open circuit. Is that the same as measuring the primary current with the secondary removed?
Winding resistance goes up with rising temperature, causing output drop and a potential runaway problem.That's the second time "hot" has been mentioned.
What is it about "hot" that makes the test condition more severe?