Should a toroidal transformer hum?

Question

Do it yourself

Good people, help me figure it out. I wind my first trance for galvanic isolation from the network 220v> 220v. I removed the torus from the Soviet stabilizer measuring 12.5x6.5x7cm. For 400W of power, the program counted 595 turns of the primary (wire diameter 1mm), taking into account network surges up to 250V. Wound 630 turns. I plugged it into the socket, if you put your ear close to the trance in complete silence, a buzz is barely audible. Tell me, is this normal, or should the trans be completely quiet at rest (there is nothing to measure its current, but the 60W lamp does not light up in series)? I also noticed that after a time, if you plug it into an outlet, there is also a barely audible rumble, but a little louder and then subsides after three seconds (also audible if you just put your ear in silence), is this normal, or do you need to wind up more turns?

The trans is not flooded with anything, between the turns there is insulation with masking tape in two layers.

Answer 1

this is normal
if there is a lot of noise under load,
then the windings can be put on varnish / paint (in short, fill with compound)

Answer 2

I guess, yes. for example magnetostriction .
measure the current consumption of the transformer at idle.
in trance calculations, they usually calculate the winding inductance along the way, do not calculate the estimated no-load current through. it should not differ much from the measured value.
if the trance goes into saturation, then a lot of energy will go into heat and the measured current will be many times greater.

Answer 3

So it should be, if you put your ear on, and the transformer does not buzz - it burned out.
To make it buzz quieter, the wire is wound more tightly and then impregnated with varnish or something else.
Fastening to the body can still be done through a thin rubber gasket.
Paraffin is not a good option, it can leak when heated.
Okay, since this is the case, I'll shake the old days.
Radio 6 number for 2015, impregnation installation =) a person winding a trance will surely cope.
With such a stray, it will even leak under the masking tape.