Transformer Help

[dmiller]

I recently returned from a trip to China where i installed an electrical system. They use 50hz and I recently removed a transformer in America that is labelled 60hz only. But it has the right turns ratio. Would I be able to use this transformer in China to go with my next shipment? Any help would be appreciated.


PS: It's a single phase transformer. Thx.

 

[iwire]

Re: Transformer Help

I suggest calling the manafacturer of the transformer to see what they have to say.

 

[petersonra]

Re: Transformer Help

many such transformers are labeled 50/60Hz.

others can be run at a lower frequency, but is not labeled as such for some reason.

I agree with the advice to contact the manufacturer.

I actually went through this one time way back when in a similar situation. The manufacturer told me to derate the transformer by some amount (that I have long forgotten) when applying a 60Hz labeled xfmr at 50Hz. I seem to recall it had something to do with the xfmr generating more heat at the lower frequency.

 

[charlie b]

Re: Transformer Help

The frequency influences the ability of the primary to generate a magnetic field. It also influences the ability of the secondary to detect that field, and to generate its own current because of that field. The lower the frequency, the lower the field. So a 60 HZ transformer operating at 50 HZ will not be able to generate the same amount of power. I would guess that the derating would be by a factor of 5/6, or 83.3%.

If you failed to derate by the appropriate factor, as given by the manufacturer, then yes, it will run hotter then it should.

I would also guess that the transformer itself would not suffer any damage, by being operated at a lower frequency, so long as you derate its available output power.

 

[rattus]

Re: Transformer Help

I moreorless agree with Charlie B.

The problem as I see it is saturation of the iron. The primary voltage must be reduced to 50/60 of its 60Hz rating. This would also reduce the core loss somewhat. That being the case, the load current could be increased a bit over the rated current.

It would seem that there is no need to reduce the KVA rating, but don't take my word for it!

 

[rcwilson]

Re: Transformer Help

Good comments. A transformer is designed for a certain volts per hertz ratio (V/Hz) so the voltage rating must drop by 50/60 to keep the V/Hz constant. ( 120 V 60 Hz = 100V 50 Hz). High V/Hz causes saturation and overheating of the core and surrounding iron.

The windings are designed to carry full load amps, so the KVA rating needs to drop also to keep the amps constant.

IMO a 480-120 V, 3 KVA, 60 Hz transformer should work OK at 50 Hz as a 2.5 kVA ,400V-100V.

But check with the manufacturer.

 

[dmiller]

Re: Transformer Help

The information is greatly appreciated, I will check with the manufacturer, and all of the answers are EXCELLENT you guys are very knowledgeable, and I agree with all of you.

Thanx a million

 

[rattus]

Re: Transformer Help

Bob, I am suggesting that since the core loss is less, the load current might be exceeded a bit without exceeding the rated temperature.

I must admit though that increasing the load current would cause additional internal voltage drops, so it may not be such a good idea to do so.