60hz RPC and transformer on 50hz supply?

mwr · Nov 8, 2015

I guess this is my week of asking electrical questions.

I have a 60hz 'only' RPC and 240-480 3ph transformer, and am wondering if they would be usable while I am overseas on 50hz mains. Both the RPC and transformer are somewhat oversize, 10hp and 9kva respectively while the largest driven motor would be 50hz 440v/400v 2hp. Does that let me get away with anything I might otherwise not be able to? Thank you for any insights.

JST · Nov 8, 2015

Maybe.... 480V 60Hz is the same as 400V 50 Hz, as far as the motors and transformers are concerned.

Problem is, it's an RPC, which means you do not have 3 phase, so you will be inputting 230V 50 Hz, presumably, with the transformer after it. That would be an issue that is not quite as easy to get around..

TDegenhart · Nov 8, 2015

JST said:
Maybe.... 480V 60Hz is the same as 400V 50 Hz, as far as the motors and transformers are concerned.

Problem is, it's an RPC, which means you do not have 3 phase, so you will be inputting 230V 50 Hz, presumably, with the transformer after it. That would be an issue that is not quite as easy to get around..

Why? Just means increasing the size of the capacitors.

Tom

mwr · Nov 8, 2015

I worried that the 50hz input causing the RPC to perform below rating could screw up everything down the line.

Another option is to cobble together an RPC with a 5hp/220v 50hz motor, which I happen to have. Would doing that improve the situation?

JST · Nov 8, 2015

TDegenhart said:
Why? Just means increasing the size of the capacitors.

Tom

It was stated to be a 60Hz ONLY device.... and 230 is the same voltage it was made to take 60Hz at.....

So it will probably draw extra current, heat up, etc. Motors don;t saturate so easily though due to the air gap.

TDegenhart · Nov 8, 2015

JST said:
It was stated to be a 60Hz ONLY device.... and 230 is the same voltage it was made to take 60Hz at.....

So it will probably draw extra current, heat up, etc. Motors don;t saturate so easily though due to the air gap.

I guess the issue is the RPC motor a "standard" design motor, in other words, passes a temperature test at full rated load or is it one that is designed specifically for RPC duty where there is no shaft horsepower? Does have a service factor greater than one?

Another option is to cobble together an RPC with a 5hp/220v 50hz motor, which I happen to have. Would doing that improve the situation?

Best solution yet.

Another option is to put the transformer before the RPC. I've done that, works well

Tom

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