Do I adjust the output voltage of a transformer if I change the input voltage?

[lvlr]

I want to buy a transformer:

The output voltage is: 34V.

But it says:
"They are specially designed to work on all standard 115V or 230V at 50Hz or 60Hz."

I live in the US, New England and the wall eletricity is 120V not 115V. So should I adjust the conversion factor?

Output Voltage = 34V * 120V / 115V = 35.48V

If this isn't how I should do this please explain what the error in my thinking is because I need to understand this.

If you want to check out the transformer I'm looking at it's:

**broken link removed**

Electrical Characteristics
Outputs	2x
Power	200VA
Output Voltage	Current
34V	3.0A

The 200VA toroidal transformers are commonly used in the noise sensitive equipment, high-end audio products, stepper motor supply, or servo motor supply. They are specially designed to work on all standard 115V or 230V at 50Hz or 60Hz. These transformers have heavier gauge wires then the normal requirement to avoid the copper lost during the full power output. The dielectric test is more than 3500V in between primary and secondary coils. Please see the test data for short circuit and open circuit. In most of the cases, this transformer can be output 20% more power from its rating at 60Hz power source without any problem. This transformer comes with 2 rubber pads and all mounting hardware.

 

[colin55]

As you will have already noted, the output voltage will be higher than 34v on no-load and will drop to 34v when delivering the full 200watts.
The no-load voltage will be as high as 40v or more, so the small voltage you are enquiring about will be swamped by the "regulation" of the transformer.

 

[crutschow]

Since this transformer specifically mentions that it has larger wires to minimize copper loss, then it's output may not vary the typical amount due to load changes and the no-load voltage may be less than 40V.

 

[Diver300]

If you look at the data sheet at https://www.antekinc.com/pdf/AN-2234.pdf it is very comprehensive. The regulation, as Carl suggests, is very good at about 3% with the voltage only rising about 1.3 V, which is much less than for most transformers of that rating.

You can't go raising the input voltage of a transformer a lot and expect the output voltage to follow. Run a 115 V transformer on 230 V and it will fail almost instantly. The core saturates and there is a big primary current.

However, for this transformer, three things are in your favour. The transformer is designed for 50 or 60 Hz, with 115 V on each winding at either frequency. Therefore the core must be designed for 50 Hz where there will be 20% more magnetic flux than at 60 Hz, so you could well go all the way to 138 V at 60 Hz without problems. Secondly, that data sheet has tests done at 120V 60 Hz anyhow, and thirdly, 120 V is within the accuracies of even less well specified transformers.

As a point of interest, the tests on that transformer show 2 W loss at 120 V, rising to 6 W loss at 140 V. It is obviously approaching saturation at that point. A resistive load would not increase its power anything like that amount from 120 to 140 V.