Trying not to face the music on 50Hz

[davey5060hz]

I have an Acme T-2-53010-S general purpose 240x480-120/240V 1.0KVA transformer which is rated at 60Hz only on the nameplate. I bought this transformer in the US and I live in Switzerland. Winding rise is 115? C, insulation class 180. I would like to connect this transformer to 230V 50Hz to get 115V 50Hz out of it. The load will probably not exceed 600 watts or 600VA. I have contacted Acme and they say derate the input voltage proportionally but this is not really practical for me. In your opinion, can I operate this transformer without problem at 230V input by ensuring load stays at 600VA or lower?

Actually looking for someone who knows this particular transformer and might know what its headroom to saturation would be. Actual mains voltage usually measures to about 227-228 V. I do have an o-scope and current probe standing by to test this transformer as soon as I get some small parts on order from the US. Hoping to not see a distorted current waveform and even if it is slightly distorted (causing secondary to be same), how serious is this on most normal loads?

 

[Smart $]

I have an Acme T-2-53010-S general purpose 240x480-120/240V 1.0KVA transformer which is rated at 60Hz only on the nameplate. I bought this transformer in the US and I live in Switzerland. Winding rise is 115? C, insulation class 180. I would like to connect this transformer to 230V 50Hz to get 115V 50Hz out of it. The load will probably not exceed 600 watts or 600VA. I have contacted Acme and they say derate the input voltage proportionally but this is not really practical for me. In your opinion, can I operate this transformer without problem at 230V input by ensuring load stays at 600VA or lower?

Actually looking for someone who knows this particular transformer and might know what its headroom to saturation would be. Actual mains voltage usually measures to about 227-228 V. I do have an o-scope and current probe standing by to test this transformer as soon as I get some small parts on order from the US. Hoping to not see a distorted current waveform and even if it is slightly distorted (causing secondary to be same), how serious is this on most normal loads?

If I were in your shoes, I'd fuse the primary at 3A and put the power to it :wink:

 

[LarryFine]

Davey, I agree. Whenever I've seen 50 Hz derating, it's been much less of a drop than the 60% you intend to load it with. My opinion, you should be okay. Check for heat build-up when you first energize it.

 

[winnie]

The _potential_ problem here is the voltage. Usually when operating a 60 Hz transformer at 50 Hz, you need to drop the input voltage by the frequency ratio to maintain constant V*T product on the primary and not saturate the core. Since the current capability remains constant, the VA rating goes down by 5/6 and other than that everything remains fine.

davey wants to operate a 240V 60Hz transformer at 230V 50Hz. As rated, this transformer should be able to operate at 200V 50Hz, 833VA. But at 230V I would expect significant core saturation unless the transformer was originally designed to operate at low flux density.

Note that since the primary can be connected for 480V, then there is the choice of using a 480V 60Hz device at 230V 50Hz. This will eliminate the core saturation issue, but will result in a roughly a 480VA rating. If the original transformer was designed with high flux density (and thus high core heating and high primary magnetization current) then the reduced flux density might let you tolerate the excess load current of a 600VA load.

Smart$ has a good suggestion, fuse it at low current and try it out. If that works fine, then clamp the scope probe on and see how distorted the supply current looks. It will always look terrible without load, so be sure to look with some significant load on the secondary.

-Jon