Previous in Forum: Servo Motor Questions   Next in Forum: Deleting Information from a Quality Analyzer
Close
Close
Close
7 comments
Rate Comments: Nested
Active Contributor

Join Date: Dec 2006
Posts: 10

60 Hz Motors and 1750 rpm

03/30/2007 2:03 PM

Is it possible to make a 60 hz motor produce 1750 rpm while connected to a 50 hz power source? I have been informed that regardless of horsepower or voltage, a 60 hz motor will only produce between 1450 to 1500 rpm connected to 50 hz power. Can someone produce something in writing that I can send a customer?

Register to Reply
Interested in this topic? By joining CR4 you can "subscribe" to
this discussion and receive notification when new comments are added.
Guru
Technical Fields - Architecture - New Member Popular Science - Weaponology - New Member Engineering Fields - Control Engineering - New Member Engineering Fields - Electrical Engineering - New Member Engineering Fields - Electromechanical Engineering - New Member Hobbies - Fishing - New Member Hobbies - Target Shooting - New Member Hobbies - Hunting - New Member

Join Date: Dec 2005
Location: Clemson, South Carolina
Posts: 1722
Good Answers: 18
#1

Re: 60 Hz Motors and 1750 rpm

03/30/2007 2:29 PM

What do you consider "in writing?"

This message is "in writing," and I'm going to tell you as a registered professional electrical engineer that 60 Hz motors run at 1450 rpm on 50 Hz power, and is indeed independent of horsepower or voltage. The reason for such is a function of number of magnetic (electromagnetic) poles in the motor and the power line frequency.

Variable frequency drives (VFD) can be used on 60 Hz motors to make them run on 50 Hz power at speeds greater than 1450 rpm.

__________________
We have met the enemy and he is us . . . Walt Kelly
Register to Reply
Active Contributor

Join Date: Dec 2006
Posts: 10
#2
In reply to #1

Re: 60 Hz Motors and 1750 rpm

03/30/2007 2:35 PM

Bill:

This idiot I am trying to satisfy wants to see something from a technical manual, that is the "in writing" I was referring to.

Thanks for your reply.

Ken

Register to Reply
Guru
Technical Fields - Architecture - New Member Popular Science - Weaponology - New Member Engineering Fields - Control Engineering - New Member Engineering Fields - Electrical Engineering - New Member Engineering Fields - Electromechanical Engineering - New Member Hobbies - Fishing - New Member Hobbies - Target Shooting - New Member Hobbies - Hunting - New Member

Join Date: Dec 2005
Location: Clemson, South Carolina
Posts: 1722
Good Answers: 18
#3
In reply to #2

Re: 60 Hz Motors and 1750 rpm

03/30/2007 3:30 PM

This is an excerpt from Freescale Semiconductor (formerly Motorola):

"AC Motors: Invented in the same era as the brush DC motor, the AC motor itself is divided into two major categories: asynchronous (induction) and synchronous. When driven by a fixed-frequency AC source with a constant load, the induction motor operates near the frequency of the input source (or multiple thereof), while the synchronous motor will operate at the input source frequency (or multiple thereof). As the frequency of the source is varied, both motor classes will accordingly change rotational speed. However, as the load changes, the difference between the input line frequency and the rotational speed of the rotor for the induction machine will be greater than that of the synchronous machine because of magnetic slip (the difference in rotor speed versus stator speed in a motor) caused by induction."

You can get more at http://www.freescale.com/webapp/sps/site/overview.jsp?nodeId=02nQXG3MYxCKS2JjTF

Other excellent sites for motor theory are http://www.reliance.com/mtr/mtrthrmn.htm and http://www.electricmotors.machinedesign.com/guiEdits/Content/bdeee2/bdeee2_1.aspx

__________________
We have met the enemy and he is us . . . Walt Kelly
Register to Reply
Active Contributor

Join Date: Dec 2006
Posts: 10
#4
In reply to #3

Re: 60 Hz Motors and 1750 rpm

03/30/2007 3:37 PM

Bill:

Thanks for your help. I am a Mechanical Engineer, so if you ever need any advice or help from my side of the pile, just let me know.

Ken

Register to Reply
Anonymous Poster
#5

Re: 60 Hz Motors and 1750 rpm

03/31/2007 9:02 AM

make sure that the motor is VFD rated, when you use a VFD with on it.

or install a gear box on the end of the motor to change the output speed.

Register to Reply
Guru
United Kingdom - Member - Indeterminate Engineering Fields - Control Engineering - New Member

Join Date: Jan 2007
Location: In the bothy, 7 chains down the line from Dodman's Lane level crossing, in the nation formerly known as Great Britain. Kettle's on.
Posts: 32175
Good Answers: 839
#7
In reply to #5

Re: 60 Hz Motors and 1750 rpm

04/03/2007 3:54 AM

Quite.

__________________
"Did you get my e-mail?" - "The biggest problem in communication is the illusion that it has taken place" - George Bernard Shaw, 1856
Register to Reply
Power-User

Join Date: Oct 2006
Location: Indonesia
Posts: 102
#6

Re: 60 Hz Motors and 1750 rpm

04/01/2007 10:43 PM

Yes, it's possible, i.e by inserting a VFD between power supply and motor.

Ask to VFD manufacturer such as Allen-Bradley (Rockwell), Siemen, Yaskawa, etc wether they have VFD with input frequency 50Hz, and output freq. max. 60Hz?

But you should consider the prices, which one is low cost, buy new VFD or Motor, it's depended on kW.

Then, you should think too, the effectiveness of that VFD. because VFD is a control unit which maintenance and trouble-shooting are required. If you will have trouble with VFD someday while you have no man who's capable in trouble-shooting, you will have new trouble to be solved then.

In short term, are you sure that you need VFD in your manufacturing line?

regards,

Register to Reply
Register to Reply 7 comments
Copy to Clipboard

Users who posted comments:

Abu Khansa (1); Anonymous Poster (1); Bill (2); kencar (2); PWSlack (1)

Previous in Forum: Servo Motor Questions   Next in Forum: Deleting Information from a Quality Analyzer
You might be interested in: DC Motor Drives, Motor Controllers, Motor Contactors

Advertisement