3PH Motor - Designed for US, but Good for UK?

At the plant I work in, we receive motors from Europe and they work fine despite all the different markings from US standard. We have not experienced any functional difference that I am aware of; I would say you'll be fine.

Yes, but not necessarily the other way around.

Since the motor is turning slower, The fields coils require more current to magnetize. This may become a problem in a number of areas:

1. The wire may not be rated for continuous use at the higher current levels. Thus causing the field coils to overheat, and possibly trip overtemperature protection cct.
2. The over current protection may trip or open.

Best - is to contact the manufacturer.

Agreed. I forgot that here we only use high end service duty motors and a standard duty motor may in fact fail prematurely. This needs a competent application engineer from the manufacturer-I wouldn't trust a sales guy.

Even if it did work it would be non-compliant if installed in a fixed electrical installation in a workplace in the UK, when inspected under the Electricity at Work Regulations. The voltage is not so much of a problem. but the different frequency is. The frequency determines speed of the output shaft and thereby the effect on the driven item, any quoted power factor would also be inaccurate and the whole ID plate would be incorrect and unless the motor was badged in integrated unit ( i.e. transformer or control unit which as badged as 415v 50Hz unit.)

In practical terms motor speed and overheating will be the two main problems

Get in touch with your supplier and have him get a Factory Engineer involved.

Reliance, GE, Baldor, etcetera have motors that have dual voltage.

I built a lot of equipment that was shipped off-shore and never had a problem using the motors that the factories specified.

I was taught that the critical factor for preventing problems was the ratio of voltage to frequency. Most motors in the USA are nameplated for 460-480V at 60Hz. This is a ratio of about 8 (for 480V). At 50Hz, a ratio of 8 suggests the desired voltage is 400V. Therefore, I believe that the motor will be within its design limits. The design of Variable Frequency Drives (VFD's) works on this same principle, reducing the applied voltage at the same rate as the frequency is reduced (and increasing it within limits if the frequency is increased).

You state that the motors are chosen with an ample reserve in their service factor, so I expect that there will be no problems with the application. Of course there are other factors to consider, such as code compliance mentioned by another post, but there should be ways to work within these limits also. The motor manufacturer may be very willing to give you a letter certifying the suitability of the motor for use at 50Hz at a reduced power output or reduced service factor.

One minor uncertainty-- you said power would be "down by 75%". I suspect you meant a 25% reduction in power output from the nameplate rating. The wording you used can mean differently.

--jmm

If connected to a VFD you could change the set up hz when programing, a common option on most VFD's & set up to run the name plate RPM's

It's probably too late to make a comment here but, do you really think it is a good idea to run something big at such low power rate?

On top of that it'll spin also slower due to the different freq over here! I guess the others stressed this already but, still - how big is that motor anyway?

When I shifted my residence from US to India I had a lot of power consuming equipment running on 115 V 60 Hz.

I had a long discussion in this regard with engineers from GE, the manufacturers of the equipment.

Here is what they had to say. In their opinion there would not be much problem by using simple transformer to bring down the Indian power voltage from 240 to 115. Now running the 60 hz equipment on 50 hz supply would pose a problem as the current loading would increase with rising temperature & would heat up the compressor on the AC. Their solution was to bring down the voltage further by 5 to 7 % from the rating i.e. in stead of 115 volts he suggested I run them around 105 to 110 volt. This also improved the power factor on the AC.

The AC after 5 years service in US gave me further service of about 9 years until the plastic body & the chassis fell apart due to harsh Indian conditions. The compressor & the fan never gave a single days trouble.