Problems with motors from europe 1

[7182]

Hello. I purchased a machine that has a motor 220/380v, 3 phase, 50 hertz. The machine seems sluggish and I just found out that my place of business only has 208 v, 3 phase. Can anyone give me any suggestions on what to do????

 

[jraef]

220V 50Hz = 4.4 V/hz. 60Hz x 4.4 = 264V.

You need a buck-boost transformer that will boost your voltage to 264V, +- 10%. Right now you are effectively giving your motor only 79% of the voltage it need to run correctly, so the torque drops by the square of the voltage reduction. You have therefore reduced the motor torque to 62% of it's capacity and unless the load is reduced to 62%, it will increase slip, pull more current and (hopefully) trip the overload relay before it catches on fire.

If you can't find a suitable buck-boost transfomer (or have no idea what one is), and alternative is to get a common off-the-shelf distribution transformer to take the voltage from 208V to 480V, then change your motor connections to the 380V pattern. That's because 380V/50Hz = 7.6 V/Hz and 480V/60Hz = 8 V/Hz, within an acceptable range. You will however need to change your motor protection devices accordingly.

"Dear future generations: Please accept our apologies. We were rolling drunk on petroleum."
— Kilgore Trout (via Kurt Vonnegut)
For the best use of Eng-Tips, please click here -> faq731-376

 

[jraef]

Oh and no matter what, your motor will be running 20% faster.

Forgot to mention alternative #3 which is to buy a VFD. But a VFD, although it can effectively provide the correct frequency, cannot create voltage from tin air. So you would STILL need to get a buck-boost transformer to get up to 220V to begin with, then use the VFD to change to 50Hz.

"Dear future generations: Please accept our apologies. We were rolling drunk on petroleum."
— Kilgore Trout (via Kurt Vonnegut)
For the best use of Eng-Tips, please click here -> faq731-376

 

[waross]

At 208 Volts you are probably at 60 Hertz. The motor will run 6/5 faster on 60 Hz. That may also be a problem.
In addition to the transformers you may need to change the drive ratio if possible or use a Variable Frequency Drive to get the proper speed.


Bill
--------------------
"Why not the best?"
Jimmy Carter

 

[itsmoked]

jraef forgot to mention alternative #4 which is to change the motor to a "local" one.

You still need to assess how the load changes with a motor now running 6/5's faster. You might need to change the motor hp rating too.

Keith Cress
kcress -

http://www.flaminsystems.com

 

[jraef]

Option #4...
What itsmoked said.

"Dear future generations: Please accept our apologies. We were rolling drunk on petroleum."
— Kilgore Trout (via Kurt Vonnegut)
For the best use of Eng-Tips, please click here -> faq731-376

 

[7182]

Thank you guys for the great advice. Nonetheless, If I get a 208v-480v transformer, off the shelf, and feed the equipment this kind of power (480v), wouldn't my control panel burn up, given that its rated for 380v?

 

[jraef]

What's in your control panel? We were only talking about the motor before.

Word to the wise; when buying electrical equipment from Europe, it's a good idea to check this sort of stuff out AHEAD of time. We can help with Engineering tips (hence the name of the website), but we are not substitutes for hiring local professionals who can see what you have on both sides and tell you what to do. Also to be honest, I'm not interested in yanking information from you one little piece at a time.

Good luck.

"Dear future generations: Please accept our apologies. We were rolling drunk on petroleum."
— Kilgore Trout (via Kurt Vonnegut)
For the best use of Eng-Tips, please click here -> faq731-376

 

[micalbrch]

If it is a standard IEC AC motor, it should have a voltage range which is eithet +/- 5 % or +/- 10 % of the rated voltage. And you can let it run at 60 Hz, too. There are of course affects on torque and power as others already mentioned. What I would do is either have a look at the manufacturers website or (even better) contact them directly. On the other hand a 220/380 V motor is most probably less than 3 kW. It will not be that expensive to buy a new one which meets the local voltage rating.

 

[OperaHouse]

I was just visiting a friends business. There waqs a hired "electrician" installing lighting. He asked me to look at this big air compressor. Said he was confused because the wiring looked single phase. The motor was 480V 19A. I showed him what terminals to connect to.

Don't assume any knowledge level of the workforce. A 380V european motor is unlikely to be also 480 or have a control transformer. A couple boost transformers are the best option if he can figure out how to phase them.

 

[djs]

380 V 50Hz motors usually have a shortened life when run at 480 V 60 Hz. Although as a manager of a motor re-working shop it WAS nice!

 

[ScusaMe]

jraef

"Also to be honest, I'm not interested in yanking information from you one little piece at a time."​

people come to this forum seeking knowledge, answers to questions, and help with problems; not arrogance, which serves no one well.
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7182....With regard to the motor, voltage is NOT the issue; volts/Hertz is.

At 220 - 50 ... that motor is designed to operate from a source that can supply
4.4 v/Hz ..... at 208 - 60 .... motor sees 3.4666 v/Hz ... and is underexcited by 13.33% (I've seen specified 208 v sources come in at a nominal 195 v, which further exacerbates the problem).

(At 4.4 v/Hz, as jraef stated, it would take a 264 v source at 60 Hz to achieve that v/Hz. Not only is that impractical, but it would create additional problems for the motor which would operate above its design parameters for speed, torque and Hp~kW)

The buck-boost solution previously proposed, while it addresses the voltage concern, does not address the v/Hz issue which is the primary concern for the motor.

The additionl concern for the motor is one of speed-torque-Hp(kW).....

To eliminate the v/Hz dilema, consider:
[li]reconnect the motor for 380v[/li]
[li]obtain a 280/480v step-up transformer of the proper kVa rating... (a 480/208v step-down transformer could be used...and use the secondary winding as the primary ... and the primary winding as the secondary)[/li]
[li] obtain a 480v VFD (v/Hz... scalar.... type is all you'd need ... don't need vector unless there additional considerations of the application you haven't shared with us).[/li]
[li] set the MAX Output parameter(s) volts and freq.... for 380/50.
Note: if VFD doesn't have ability to limit max volts and frequency, then set the MAX SPEED parameter for the nameplate RPM of the motor.[/li]

That will take care of only the motor issues.

Since we have no knowledge of the make-up of your control panel, we are unable to offer any advice for resolving how to make a European design find happiness in the USA/Canadian?? world.

You could, of course, begin a very necessary dialogue with the manufacturer (OEM) of the machine that you purchased; even if you are not their primary customer for this machine ...i.e., you purchased it from a 3rd or 4th party.

I somehow get the feeling that you tried to save a few $$$ by buying something second hand without understanding all of the ramifications. Unfortunately, its gonna cost you more in the long run to get it up and running. Perhaps an old expression: Penny Wise and Pound Foolish is or Lessons Learned the Hard Way .... is apropos ???

Good luck

 

[electricpete]

"Also to be honest, I'm not interested in yanking information from you one little piece at a time."

people come to this forum seeking knowledge, answers to questions, and help with problems; not arrogance, which serves no one well.

Jeff is one of the most helpful and knowledgeable on the forum. There is no arrogance in sight. He was just being honest with you.


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(2B)+(2B)' ?

 

[electricpete]

Sorry, his comment was not directed to you... I meant he was being honest with the op.

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(2B)+(2B)' ?