50/60 FAQ
50/60 FAQ
(OP)
Hello fellow members!
It was pointed out in the recent post "converting 60hz motor to 50hz" 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.![[orientalbow] orientalbow](https://www.tipmaster.com/images/orientalbow.gif)
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.![[cry] cry](https://www.tipmaster.com/images/cry.gif)
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
It was pointed out in the recent post "converting 60hz motor to 50hz" 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.
![[orientalbow] orientalbow](https://www.tipmaster.com/images/orientalbow.gif)
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.
![[cry] cry](https://www.tipmaster.com/images/cry.gif)
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





RE: 50/60 FAQ
Basically it's 50:60, or 60:50.
New voltage, = Old voltage x 6/5 or 6/5 as the case may be. +/- 10%
New speed, = Old speed x 6/5 or 6/5 as the case may be.
New horsepower, = Old horsepower x 6/5 or 6/5 as the case may be.
Usually the "Gotchas" don't "Getcha". 90% of the 'gotchas exist in the minds of those who have never actually done frequency conversions. This is not to deny the finer points usually raised but to point out that these points are usually of such a small magnitude as to have no noticeable effect.
Even the cooling issue is not an issue in 99+% of conversions.
The other common factor is wye to delta conversions and vice versa with NEC motors.
respectfully
RE: 50/60 FAQ
I would have only added something about how the V/f ratio is the same for 460/60 as it is for 380/50 so that those using those voltages know that it's kind of a no brainer other than the other points you made. Sure anyone with a calculator can figure that out, but we are a lazy lot sometimes.
Eng-Tips: Help for your job, not for your homework Read FAQ731-376
RE: 50/60 FAQ
BK
RE: 50/60 FAQ
FAQ237-1224
Thanks for the feedback waross and jraef!
I worked in your comments.
waross; I think you might revise your 90% number downward if you worked in refrigeration.
As others know, I often work with private rail cars. Refrigeration is the key technology that allows them to be habitable for use by people because they usually have acres of glass and huge insolation numbers(think Super Scenic-Cruiser dome cars with 180 degree glass roofs). The heat gains are so high that you cannot "air condition" them, you must actually "refrigerate" them. Most often they are supplied by under-slung generators. We have seen many, many, large very expensive compressors that have failed due to running them at lower frequencies. 59Hz is enough to toast them with almost a guaranteed result.
I agree some guy with a lathe where the motor essentially runs unloaded or with a 10% load duty cycle could probably get away with murder with respect to 50:60 stuff. Likewise fan people and to some extent centrifugal pump users and probably any other low duty cycle loaded motors; chippers, some conveyors, saws, drills, etc. etc. I think 100% loaded applications like refrigeration, plant air compressors, positive displacement pumps, vertical conveyors, etc, need careful consideration of the possible problems of frequency changes.
It mostly comes down to those pesky loads and what they be. Which is what I hope posters will now be able to focus more on.
As an engineer with a question about a frequency shift I want to know the general hazards to my equipment as apposed to a "it will probably work fine".
Thanks and respectfully:
Keith Cress
Flamin Systems, Inc.- http://www.flaminsystems.com
RE: 50/60 FAQ
The centrifugal switch part is in the FAQ.
I would welcome any specific suggestions about Cap start/run single phase 50:60 motor concerns. I don't understand the capacitor ramifications enough at this point to say anything about it.
Anybody care to jump in on this subject?
Keith Cress
Flamin Systems, Inc.- http://www.flaminsystems.com
RE: 50/60 FAQ
Re the capacitors, at lower frequency, the inductive current will be more (20%?) and the capacitive current will be less (20%?). You may have to add some capacity going to 50 Hz. For most applications probably not. And I am thinking about the -20/+80% tolerances you mentioned for capacitors. If in doubt, add 40% more capacitance.
Going to 60 Hz. Don't worry unless you have a machine that may be damaged by extra starting torque. If you have high starting current try reducing the capacitor.
I'd be inclined to get the voltage right and try it. If it is a demanding application that is having problems starting then I would add some capacity. (50 Hz.)
60 Hz. I wouldn't worry.
I had a couple of very large sliding doors 8 or 9 years ago.
The owner bought heavy duty industrial operators with the smaller motors. The motors couldn't start the doors moving. I doubled the capacitance on each one and they have been working for years. We had a capacitor failure a few years ago The capacitor was replaced with the same size and it's been running ever since.
Any other comments?
RE: 50/60 FAQ
RE: 50/60 FAQ
I am trying to sum up your capacitor comments into something.. short and sweet for our FAQ.
To wit:
############### Proposed addition to FAQ #############
Some single phase motors have start or run capacitors and some both. If the motor is being shifted from 50 to 60Hz then their effect will increase. This will usually pose no problem.
Alternatively taking a motor from 60 to 50Hz will reduce the capacitor effects. This will result in possibly lower running and starting torques. This may mean the motor cannot successfully start its load or maintain running a load.
A failure to start may result in a rapid burnout(seconds) so this should be carefully monitored initially. Larger capacitors or additional ones may be needed.
########################################################
davidbeach; Interesting. Would this be a second or third order effect as apposed to a first order one?
Thanks.
Keith Cress
Flamin Systems, Inc.- http://www.flaminsystems.com
RE: 50/60 FAQ
RE: 50/60 FAQ
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I don't suffer from insanity. I enjoy it...
RE: 50/60 FAQ
I like your addition to the faq, itsmoked.
respectfully
RE: 50/60 FAQ
Keith Cress
Flamin Systems, Inc.- http://www.flaminsystems.com
RE: 50/60 FAQ
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.
Regards
Petronila
RE: 50/60 FAQ
Thank you for a very well written FAQ I did attempt sending you a message using the Send a comment to itsmoked About This FAQ feature which may not have gone through.
I have a question about the paragraph on single phase complications in the last sentence you state "Likewise a 50Hz motor placed into 60Hz service may switch off the start winding at too low a speed for the motor to make the transition to running."
It is my understanding this motor will run 20% faster and a centrifugal switch is designed to open and deenergize the start winding at rated speed, How is it the start winding can be switched off at too low a speed?
Thanks, Chuck
RE: 50/60 FAQ
Please note, I picked a figure to illustrate Keiths point. I have no idea what the operating speed may actually be or if it will make a difference. I have done several conversions, both ways, but only on three phase motors.
respectfully
RE: 50/60 FAQ
Under this condition the motor would for sure turn into toast quickly, Most motors I use are designed for 50/60 Hz operation.
Thanks, Chuck
RE: 50/60 FAQ
Yes failure to start can burn them up shockingly fast.
To essentially repeat waross's fine response:
The C. switch is going to operate at its design speed. For an example on a 50Hz 1425RPM motor the switch might open at say, 1200RPM (84% of full speed) because the motor has reached a point where it can sustain accelerating the load up to its rated RPM.
Moving the motor to 60Hz service means the motor will now be trying to achieve 1725RPM but remember the switch is still going to open at 1200RPM or only 69% of rated speed. This may be too slow for the motor to transition.
Yes a 50/60 motor will be designed correctly so that this is not problem but a strictly 50Hz designed motor 'could' have a problem.
Keith Cress
Flamin Systems, Inc.- <http://www.flaminsystems.com>
RE: 50/60 FAQ
Thanks, I am now crystal clear and understand completely.
Soon we are getting a machine made in Germany from Poland,
this knowledge will help.
Sincerely, Chuck
RE: 50/60 FAQ
That's great! I love it when someone can say that about something we've been working to illuminate.
Good luck with your machines.
Keith Cress
Flamin Systems, Inc.- <http://www.flaminsystems.com>
RE: 50/60 FAQ
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
RE: 50/60 FAQ
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