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Mahanteshy
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Stall Time Of Motors

05/27/2011 11:56 PM

how much is the stall time or locked rotor withstand time (LRWT) for motor?
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Tornado
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#1

Re: stall time of motors

05/28/2011 1:20 AM

It probably depends on the specific manufacturer's data. (There would be as many formulas as design variations, but no one-size-fits-all calculation.)

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hien.nguyenquoc
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#2

Re: stall time of motors

05/28/2011 4:10 AM

LRWT is the time in seconds that the motor can withstand stalled current without damage.

Depends on its state (hot or cold), we can assume that stall time could be 10 to 15 seconds.

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TonyS
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#3
In reply to #2

Re: stall time of motors

05/28/2011 7:03 AM

I think at 5 seconds a motors got problems if it hasn't started turning.

Some motors will withstand far longer, crane motors for example, but they are built like tanks!

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hien.nguyenquoc
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#8
In reply to #3

Re: stall time of motors

05/28/2011 11:17 AM

US motors normally are built like tanks. If in dout, you can ask our every US mates.

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hien.nguyenquoc
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#13
In reply to #3

Re: stall time of motors

05/30/2011 11:58 AM

Again, it would depend on the type of motor and the method of starting. You will see the motor for clinker grinder start very slow as if it is stalling.

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msamad
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#4

Re: Stall Time Of Motors

05/28/2011 10:24 AM

See this thread. You will find lot of good information there in this regard.

http://cr4.globalspec.com/thread/67824/Locked-Rotor-Withstand-Time-LRWT

- MS

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hien.nguyenquoc
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#5
In reply to #4

Re: Stall Time Of Motors

05/28/2011 10:37 AM

Haha, I know you will surely come back... with a link. msamad. Yeah, I have gone through it my mate. Is that exactly NEMA request the stall time should be that much?

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msamad
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#6
In reply to #5

Re: Stall Time Of Motors

05/28/2011 11:05 AM

Can anyone argue that it is not mentioned in NEMA MG 1, section 12.49? It is exactly what NEMA requires and those who are familiar with NEMA MG 1 know well about it. I am in doubt your mate have ever read it.

- MS

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hien.nguyenquoc
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#7
In reply to #6

Re: Stall Time Of Motors

05/28/2011 11:14 AM

Just a little pricking... I know why you got 5 votes for a GA.

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#9

Re: Stall Time Of Motors

05/29/2011 12:18 AM

Until the unit starts producing smoke or 5 seconds after manufacturer's recommended LRA, depending on which occurs first!

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brich
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#10

Re: Stall Time Of Motors

05/29/2011 7:16 AM

why do you need to know?

Are you installing protection equipment to prevent rotor lock or trip the control gear if you get a locked rotor, or are you just making a general inquiry for yourself?

The submersible motors I use and the associated and matched control equipment monitors motor function and if we get a locked rotor, there are several protection settings that will trip the motor contactor, those are "Stall", "Locked Rotor", "Instantaneous Over current" to name a few, and all of these will trip in milli seconds.

As it has been suggested, contact the makers to see what info you can get from them.

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Fredski
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#11

Re: Stall Time Of Motors

05/29/2011 10:13 AM

If you explained the actual problem you're experiencing you'll get more quality responses.
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brich
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#12
In reply to #11

Re: Stall Time Of Motors

05/29/2011 11:00 AM

here we go again.. a "off topic" vote for us both... but no-one wants to say why!!!

Please, whoever you are... have the back bone to say why.. i'll not be offended.. I might even learn something!! and I'm sure Fredski won't mind either!!

See..... I've even said I'm off topic!

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#14

Re: Stall Time Of Motors

05/31/2011 4:24 AM

The stall time is limited to the difference between the contactor energising and the overload trip operating.

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Anonymous Poster (1); brich (2); Fredski (1); hien.nguyenquoc (5); msamad (2); PWSlack (1); TonyS (1); Tornado (1)

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