50/60 FAQ 4

[itsmoked]

Hello fellow members!

It was pointed out in the recent post [purple]"converting 60hz motor to 50hz"[/purple] that this question is the most frequent we see.

It is, as we all know, a fairly complex issue fraught with niggling lurking gotchas. Unfortunately we find ourselves having to work though the basics before we can even address those small often important details.

It was suggested someone produce a FAQ.

Tah Dah! I have done so.

As soon as it is released I would appreciate you all taking a look at it so we can make sure everything you feel should be in it is covered and that what is covered is correct. I was told I once made a mistake.

Please keep in mind that it is written to cover the typical 'guy faced with a machine spec'ed for the "other" frequency', not all the finer details. If those questions come up, and they could more frequently now, then we can add to the FAQ (chapter 2) or create an additional one.

Stay tuned I'll put it up soon.

Keith Cress
Flamin Systems, Inc.-

http://www.flaminsystems.com

 

[Marke]

Hello petronila

Take care with the new European 50 Hz Six Leads motors designed at 400 (Wye) /230 (Delta) because they work proper in America only at 480 Volts not at 230 Volts.

The only way this motors work proper at Both voltages in America is 480 Volts(Delta) and 230 volts (Two Wyes).So you Need 12 leads.

This is not correct. While the motors in the USA may be normally configured as delta double star, there is no reason that you can not run a European motor on 60Hz
Connected in star, the motor will operate on 400 x 6 / 5 = 480 volts and in delta connection, it will run on 230 x 6 / 5 = 276 volts. If you run on 230 volts 60Hz in delta, the flux will be reduced by 16.6% so you will need to derate the motor relative to what the rating would be at 276 volts.

Best regards

Mark Empson

http://www.lmphotonics.com

 

[petronila]

Marke,

Yes I have a mistake and thanks for the correction, because the 400 Volts-50 Hz wye connected could run Proper at 480 Volts- 60 Hz in Wye conection not in Delta. Really the problem exist when you need to run this European six leads motor at low voltage at 60 Hz.

For the IEC Motors designed with 6 leads the problem is refered to the sqrt 3 voltage ratio for Delta/Wye Connection:

480 V/sqr3 = 277 Volts, if you runs this motor at 230 V the torque drops by square of voltage ratio.
((230/277) = 0.83, (0.83x0.83) = 0.69)

At 60 Hz The Speed will increase by 60/50 = 1.2 , But the motor is still underpowered for application, 1.2x 0.69= 0.83

Due to the 50 Hz motor will work proper wye connected at 60 Hz- 480 Volts this same motor will work proper Two Wyes connected at 60 Hz-240 Volts.

Regards

Petronila