Frequency Converters

It would almost certainly be cheaper and more effective to replace the motor with one designed for the correct frequency.

Frequency converters do exist, but they are either a rotary machine - a motor coupled to a generator, or an electronic motor speed drive which, with rare exceptions needs a 3-phase motor and not a single-phase.

You could run your 60Hz motor on 50Hz, but it is my understanding that cooling will be an issue, and that it is best practice to keep the V/Hz ratio constant ie the supply voltage should be reduced to 50/60 x 230 = 192V.

Hello to the person with the frequency enquiry

In over 50 years working in the electrical trade and installing numerous motors and motor control equipment, all on the 50Hz system in Australia, the only problem I have ever accounted is with excessive heating and I have never seen a motot develop any serious problems within a year or two of being connected at 50 Hz instead of the nameplate rating of 60 hz, although several motors with multiple connection combinations have had to be reconnected in a suitable manner to restrict the current. The last one I had to install was a 240V 3phase 60 Hz unit that had a combination of Series and parallel connections with 9 sets of coils. Something I had never seen before, but had no option as it arrived late to be connected into a plant waiting to produce I connected it to 415V 50 Hz supply That ran for years driving the supply for a Hydraulic motor in a concrete block manufacturing plant. It was an old type TEFC unit with a tubular cover and did run fairly hot, but the last time I saw it it had two years duty as a second hand unit working long hours under fairly constant load. Before I spent a lot of money I would connect the unit and trial it under load conditions and monitor it for a reasonable period, for output and temperature. Lost speed can be compensated for with a different pully size if not directly coupled. Unfortunately if it is to be directly coupled you have a underspeed unit, which may or may not be a problem depending on demand. This may not be acceptable for the purists among us, but then they seldom have to make uniys work in the field

Regards
Bill P.

Go to www.globalspec.com and type 'frequency converter' into the search box.

Enter your specs and several manufacturers will come up. Depending on the power level it may well be cheaper to replace the compressor/motor.

Most frequency converters allow you to change the maximum frequency output. I've seen a few where people have set it to as much as 120Hz.

regards,

Vulcan

You could use a VFD. It would also allow you to keep your starting amps under control so you could avoid demand charges as well as change the frequency. Replacing the motor with a 60hz one - as one of the other forum members said is probably your best bet. Edmund

As I understand the problem is not with the motor.

The compressor if run at 50Hz instead of 60Hz will have the output down (almost proportion to N, with a correction factor may be about 0.95 so the flow is likely to be about 50/60*0.95 = 79%

If this reduction in the capacity does not matter to you, I don't see why you can not go ahead at the cost of a bit of efficiency loss.

Else if possible and economic, change the compressor rather than going for the extra cost of putting a VFD (and additional component → additional drop in system reliability and hence availability as I look from equipment maintenance direction)

Buy the right 50 Hz motor. That is the best and cheapest way in the long run.

Why buy 60Hz equipment in the first place, because it was cheaper and made in a country where 60Hz prevails, therefore calculate in the ciost of a replacement 50Hz motor before ordering if the manufacturer cannot build with 50 Hz motors for your area(USA usually has problems with smaller companys in that area.......!)

Hi Andy,

I would say to run his 50Hz motor before buying a new one if it does the job OK if it burns out then buy a new one.

If he can stand the downtime IF it fails......

Why he bought it with a 60Hz motor in the first place is a big question. Surely a manufacturing company can be worldly enough to offer both styles of motor with the correct pulley already mounted and tested......