Question on converting 220V 50Hz to 110V 60Hz

Hello nyanthar

You are in a UK supplied area, with US supplied equipment.

Frequency is the issue, and there is no cheap and easy way around it.

Although the compressor will work, you risk burning out the windings, because it does not get to the designed speed.

It would be best to replace the compressor with the correct Voltage/Frequency unit, and sleep easy at nights.

Kind Regards....

When I was younger I had a motor coupled to an alternator with an appropriate v drive. (The thing was called a pig because of the sound it made)

This response is perfectly on-topic. What Hendrik is referring to is an MG set for those of fewer years. If using synchronous machines, a gear ratio change is in order to get the correct frequency. I'll put a GA in to cancel out that OT.

nyanthar; did you run it long enough to cool down? did the internal thermal overload open? the returning freon sprays over the motor winding to cool them, more then likely there is less iron in your motor, so the current would be higher,also the load on the motor would be higher from warm system perry

Can`t you find a new moter or a used one on ebay to match your power supply that turns at the right speed? I am not sure how it is coupled but find a welder if you need to adapt. Good luck

Pl note that the power (current) drawn by a hermatic compressor used for refrigeration purpose varies greatly. Note that it is not 'RLA' but it is 'LRA', means Locked Rotor Amps. It is the max current the compressor draws when the rotor is locked by any means.

by using 50c/s freqency in place of 60c/s will only reduces the speed of the motor or compressor, thereby reducing the capasity to 83%. In your case it does not matter.

Changing the compressor as you have done is not correct and will create an imbalance of the system. The system shall be designed to condense and evaporate the refrigerant pumped by the compressor. By increasing the capasity of the compressor, it will lead to imbalance.

In the first instance, I hope you must have checked the current on the compressor immeditely on starting the system which will be always 150% more than the rated current. This is because, the compressor will get ample 'return gas' which is already lying evaporated in the system during stoppage. To pump all the surplus gas, the compressor takes more load.

After a time of 3 minutes, the compressor pumps out all the surplus gas and the discharge pressure reaches around 160 psi while reducing the suction pressure to around 50 psi, the compressor will not get as much gas as in the above referred case. Hence the compressor takes a load of 150% or more at the time of starting and reduces to 100% with in 3-5 minutes and is in stead state. When the refrigerator inside temperature has reduced, the load on the compressor will reduce proportionally.

You have done absolutely correct in using a step down transformer. But replacing the compressor is not at all a correct solution. Pl note that the replacement of compressor has to be done by experts only. After the system leak test is completed, the system shall be evacuated using a 'deep vaccum pump' to remove all the air and moisture. Then only the gas shall be charged. Any air remaining in the system will form as a blind pocket in the condenser and reduces the performance of the condenser and eventually the system performance.

Hope your problem is solved. Should you need any further detail contact me at kiranengineers@rediffmail.com or kiranengineers2008@yahoo.co.in

TP

Hi Guest,

Thanks for trying to help.But the ampere I had mentioned was RLA(Running Load Ampere).I forgot to mentioned that all the amperes were in without load (refrigerant ) condition.

The LRA(locked rotor ampere) for the first compressor was about 26A and for the second was 32A.

Thanks.

Read this, it sums it up.

http://lmphotonics.com/motor_50Hz_60Hz.htm

Dear Friend,

With the help of information given in the site suggested by you, If we provide a step down transformer of 230V,50Hz to 92V,50Hz to the subject compressor of 110V,60Hz, it may work. Is it correct???

I think to get the right amount of refrigeration, speed of the compressor motor is very important and with 50Hz supply to a 60Hz motor (AC) the speed will come down considerably.

The only solution seems to use either a Frequency Converter as some one suggested or refer answer 6 & use 'sung transformer' with IC circuit which can supply the desired Voltage and frequency. I did not hear about this sung transformer earlier.

"With the help of information given in the site suggested by you, If we provide a step down transformer of 230V,50Hz to 92V,50Hz to the subject compressor of 110V,60Hz, it may work. Is it correct???"

It will work in that the motor will not burn up. BUT, at the slower speed on a compressor, it will move less refrigerant and therefore take proportionally longer to do the required work.

I have no idea what a "sung transformer" is. I think that perhaps he was not proficient at English and was trying to say "...220V to 110V by using transformer..." and then his referring to using an IC would essentially be the equivalent of using a VFD.

But the problem is, you cannot use VFDs on most types of single phase motors. VFDs can only work on PSC and Shaded Pole motors, neither of which are too common in refrigeration compressors.

Gentleman,

Thank you for enlightening. I am in full agreement with your first two answers. However, regarding Single phase VFD for the compressor motor, I am not very sure as why it shouldn't work. I have come across many single phase VFDs in Petrol filling stations and small plastic laboratory extruders where you require variable speed of motor keeping V/f ratio constant (within limit).

Could you please give the details of PSC and Shaded Pole Motors and how they differ from a refrigent motor?

Warm Regards,

NATWAR.

Most of the compressor motors operate as a PSC motor. Some times a hard start kit is added and then it works as a capacitor start motor.

You should be able to use a vfd to operate the compressor. A unit to run a PSC motor should work. You may or may not need the step down transformer.

Verify the motor name plate voltage. Most motors that are refered to as 110 volt are actually are 115 or 120v. If the motor is 120v, 60Hz and you are trying to operate is on 110v, 50Hz you are way off from the design of the motor.

The drives have the capability of controlling the voltage and frequency. You should be able to set the maximum voltage of the drive according to the name plate and then the frequency at 60 Hz. Set a short ramp time probably two seconds. Connect the Y1 or actual designation for the compressor control wire. You may need to use a relay as most drives operate as a dry contact. The compressor control wire will likely be 24v.

Using this information as a start your drive manufacturer should be able to help you complete the hookup

Dwight Hanson