Need Information for AC Motor.

Go back to the machine's original manufacturer and ask for a replacement motor of the correct specification.

Also, determine the cause of the problem and eliminate it, thereby avoiding the need to replace the motor again in the future.

what is your system. is it single phase or 3 phase

It will probably work, what is your mains voltage and frequency?

Dear Sir,

Machine supplier not exist now. Original motor was connected with 470VAC (Thee Phase) 60Hz, but now I want to connect 500VAC three phase motor 50Hhz. is it right?

Well, the performance of the 50Hz motor at 60Hz is indeterminate. That is why a replacement motor, like-for-like, is of great interest in keeping the machine, whatever it does, in production.

Consider what might happen if this 50Hz motor were not up to the task, and make the right choice for the application.

you can do it as you are connecting a motor rated for 50Hz 500V againist 60Hz 470v. it will match( Flux characteristics.

No

What about RPM?

The motor will run at 5/6 rated speed, run hotter and draw more current.

May be OK, may not.

Hi Lyn,

I'm an HVAC guy so I might be wrong here but, if a motor designed for 50 Hz is operated at 60 Hz wouldn't it run faster instead of slower?

Troy

Sorry,

You're right. 6/5 speed.

Dear Sir, JRaef,

As you explained earlier, In this case current will increase ?

Please provide following information:-

1. What is supply 440 V, 3 phase, 50 Hz?

2. What is the rating of old motor and new motor.?

3. What is the application for which this motor is required?.

4.What is enclosure T.E.F.C or T.E?.

Without such information if will not be possible to clarify the suitablity of new motor.

1. What is supply 440 V, 3 phase, 50 Hz?

470VAC, 3 Phase, 60Hz

2. What is the rating of old motor and new motor.?

old= 2HP, 470VAC, 3 PHASE, 1400RPM, 60Hz

New= 2HP, 500VAC, 3Phase, 1400RPM, 50Hs

3. What is the application for which this motor is required?.

Motor working on machine for suction blower.

4.What is enclosure T.E.F.C or T.E?.

I don't know about it?

Best Regards,

In this case, the Motor will run faster by 6/5 times it's rated rpm (on the new motor), but since the supply frequency is higher, the motor will draw less current (Higher impedence). The increased rpm capability will compensate for the possible power loss....

If the original 2 HP was generously rated, you might be OK and the motor will run fine. (the cooling will be OK ...).

Another consideration would be if the motor application is of a "speciality" design wherein the torque curve has been intentionally manipulated to provide maximum load starting force at a speed (RPM) other than a conventional "off-the-shelf" SC motor.

You must gather and record all data from the original motor nameplate and/or IOM then match the new motor data precisely item by item.

All motor nameplate numbers and letters have a specific meaning to identify the design operating characteristics.

If you contact a major motor manufacturer distributor and surrender the gathered information they will provide you with their "direct" replacement technical specifications. (If one manufacturer cannot match the old unit solict a different one until you find a competent replacement motor with the same design specifications.)

Some electrical motors are now being designed that will operate at 50Hz as well as 60 Hz without suffering major failure (HP tradeoff).

However if the motor is not designed to do this it will most likley fail especially if operating at anywhere near full load demand.

If the motor is capable of operating at both 50 & 60 Hz, the nameplate data will indicate so.

Sir,

Please check for an error on your answer 2. You said: old= ... 1400RPM, 60Hz. That RPM is not a standard one for a 60Hz motor (usually 1725-1750 for 4-pole, or 1125-1160 for 6-pole motor). 1400RPM is at the low side of the typical range for a 50Hz motor. Is it possible that you have an error in reading the old motor's nameplate--that it is in fact a 50Hz motor?

--John M.

Now you have got answer from LAA which is absolutely correct.

Dear Sirs & specially suresh sharma & LAA,

Thank you very much for your detailed guide line. motor working perfectly as per your advice.