Voltage Transformer ratings


i build a 3 phase current & voltage version with an arduino nano.
for the VT’s i choosed GERTH 150.09 with 9V at 0,35VA.
The VT’s get quiet warm.

what are the minimal ratings?

hear is the scematic.

regards maik

Welcome, Maik, to the OEM forum.

Your transformer has a rated full load current of 36 mA, the only load on it is the 110 kΩ voltage divider, so I think about 82 µA. I do not think that will be a problem.

It is much more likely that the transformer has been designed to be as small as possible, and it will be warm. The data says “Temperature class - ta 70°/B” which allows an 80 °C temperature rise of the windings, so if the outside is warm, I think it is OK.

Hi Robert,

thank you very much for your reply.
the transformer has a temp of ~40-50°C on the outside.
i thought this is quiet to much for only 0,000081818 Amps at 9V and 110k.
even under idle Voltage of ~ 15 V at 110k it is only 0,000136364 Amps = 0,002045455 W.

regards maik

There are two ways that a transformer can get hot. I think you are thinking of what we call “copper loss” - heating of the windings by the current passing through them. I think in your case it is “iron loss” - power that is being used to change the magnetic field in the iron core of the transformer - that is causing the heating.