Isolating transformer disparity on reading volts out

[paddy ryan]

I have a BLOCK TIM 100 isolating transformer, designated at 230 Volts 1 amp primary and 2x115 volts out, or 230 volts out, but my DMM reads the output as 265 volts. Why is that? Advice please?

 

[crutschow]

my DMM reads the output as 265 volts.

What is the measured transformer input voltage?

Transformers have a rated output voltage at their rated load, so an unloaded transformer will likely read somewhat higher to allow for voltage reduction under load due to primary and secondary winding resistances.

 

[rjenkinsgb]

As Crutschow says.

The variation from no load to full load is called the Regulation; for a tiny transformer it could be eg. 30% high off load, for larger ones the difference gets steadily smaller.

The one you have has a regulation of 8% according to the data sheet? (1.08 x nominal voltage, off load).

If you are in the UK, the mains input could easily be anything up to 250V, which will increase the output proportionally.

 

[Diver300]

With the no load output of 1.08 times nominal, 265 V mean that the input is 245 V, which is well in the normal range for the UK.

 

[Diver300]

I have a BLOCK TIM 100 isolating transformer, designated at 230 Volts 1 amp primary

https://www.block.eu/en_EN/productversion/tim-100/
That transformer is rated at 100 W, so on 230 V primary that is a bit under half an amp.

 

[paddy ryan]

Thanks for all that, it eases my mind. There was no load on it when I tested it for the output, so it all makes sense. Thanks again.