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user-deleted-1099
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Join Date: Dec 2007
Location: Honolulu
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Devices Running on Different Hertz (Hz)

02/10/2010 1:46 AM

Wondering if any one has any data on the effects of running electric motors and refrigeration compressors designed for 240 VAC 50 Hz and running on 220/240 VAC at 60 HZ?

How significantly is service life reduced?

Ohter potential problems?

Looking forward to some input.

Also any good frequency convertors out there?

Edward

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Pathfinder Tags: AC Compressors frequency convertor frequency fluctuation motors
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Anonymous Poster
#1

Re: Running on different HZ?

02/10/2010 2:13 AM

Too many posts on 50Hz equipments on 60Hz and vice-versa.

Infact there was a lull now, before you came in

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user-deleted-1099
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#7
In reply to #1

Re: Running on different HZ?

02/10/2010 10:45 AM

Thanks, I did not take time to search the forum yet.

Ed

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user-deleted-1099
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#11
In reply to #1

Re: Running on different HZ?

02/10/2010 10:58 AM

Thanks glad I came in with the question to get things going again!!!

Ed

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Electronaut
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#2

Re: Running on different HZ?

02/10/2010 2:30 AM

Given below is a partial answer to your question. Hope you will find it useful.

Running a 50Hz electric motor (IM) on 60Hz will result in the following:

1) Slight improvement in the running power factor.

2) A decrease in the starting and breakdown torque. The decrease can be as large as 40% when operating a 50Hz motor at 60Hz.

3) A decrease in the starting current. The decrease can be approx. 10% when operating a 50Hz motor at 60Hz.

4) Full load current will be slightly more than the rated (50Hz).

5) Slight drop in the efficiency of the motor.

6) Increases the speed of the motor and thus an increase in friction and windage losses.

7) There may be a premature failure of motor bearings accompanied by increased vibration levels.

Operating a 50Hz motor at 60Hz at the same voltage level will change the V/f ratio of the motor. In order to operate the motor at near to the rated V/f ratio, you will have to run the motor at an increased voltage. Thus, a 60Hz operation will also lead to change in the operating voltage of the motor. Maximum allowable combined variation of both frequency and voltage for a motor is +/- 5% against the rated values. Hence, it is not advisable to run a 50Hz motor at 60Hz until and unless it is designed to be used under such circumstances.

Nowadays, dual frequency electric motors are available in the market that can be comfortably run at both 50 and 60Hz.
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user-deleted-1099
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#8
In reply to #2

Re: Running on different HZ?

02/10/2010 10:48 AM

Thanks Eltronaut,

Very very helpful Ican now give a proper answer to my concerns.

Aloha from Hawaii.

edward

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lyn
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#3

Re: Running on different HZ?

02/10/2010 4:14 AM

For a bazillion other discussions of this same topic, just type 50/60 Hz operation into the Search this forum box to the right.
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Anonymous Poster
#5
In reply to #3

Re: Running on different HZ?

02/10/2010 8:49 AM

That's what I said in #1 and got ans OT but you didn't .
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lyn
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#6
In reply to #5

Re: Running on different HZ?

02/10/2010 10:01 AM

That's not what you said at all. Quit whining!
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user-deleted-1099
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#9
In reply to #3

Re: Running on different HZ?

02/10/2010 10:50 AM

Thanks Lynlynch, I did not take the time yet. Where in Az are you... I'm a native son -tucson '46

Aloha from hawaii

Ed

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Anonymous Poster
#4

Re: Running on different HZ?

02/10/2010 5:28 AM

Dear Edward,

Within my experience as an electrical engineer for the last 6 years and as an electrical technician for more than 10 years, there are many factors which could effect directly or indirect on electric motors or compressors or there efficiencies outputs, such as the location, condition, how frequently get started, loose connection, vibration, variation in local voltage, length of power supply cable (fed), power factor, mechanically lubrication while regular maintenance (PM), and equipment design quality.

you can use Variable Speed Controller for changing motors speed such as Altiva (Allen Brindly products) but it's initial cost is high.

Best regards,

ARB
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user-deleted-1099
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#10
In reply to #4

Re: Running on different HZ?

02/10/2010 10:54 AM

I will look into options further...bets seems to be to change out three AC units and one motor unit and upgrade wiring

Edward

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msamad
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#12
In reply to #10

Re: Running on different HZ?

02/10/2010 2:15 PM

Go to the previous thread http://cr4.globalspec.com/thread/33399/Motor-Frequency and read the comment # 2. A pretty good information is there.

- MS

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Anonymous Poster
#14
In reply to #12

Re: Running on different HZ?

02/11/2010 12:38 PM

The previous thread was also helpful; thanks for the direction
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sceptic
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#13

Re: Devices Running on Different Hertz (Hz)

02/11/2010 6:20 AM

Once had to run an air compressor for an oxygen plant.

It was designed for 60Hz and our supply was 50Hz.

The motor ran OK, but the compressor needed to be sped up because it had a resonance near 3000 rpm, which had died down by 3600.

So check for similar problems if you want to run mechanical equipment at a different speed to it's design.
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Anonymous Poster
#15

Re: Devices Running on Different Hertz (Hz)

02/12/2010 7:19 AM

http://cr4.globalspec.com/blogentry/11301
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