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  #1  
Old Wed 18 November 2009, 05:03
KenC
Just call me: Ken
 
Klang
Malaysia
Coil Inductance measurement, is this normal?

I bought these 86HS9801 specs
It says the coils has 4.1mH

I measured the inductance between the wires & the results as follows

Coil A, 3.64mH, 3.67mH, 3.71mH, 3.67mH (Red-Yellow)
Coil B, 3.61mH, 3.46mH, 3.53mH, 3.80mH (Orange-White)
Coil C, 3.62mH, 3.42mH, 3.56mH, 3.77mH (Brown-Green)
Coil D, 3.65mH, 3.71mH, 3.72mH, 3.66mH (Blue-Black)

Are they consider normal?

I'm using 48Vac tranny should give about 65~66Vdc,

Consider these,
32*sqrt(3.4) = 59V (lowest measured value)
32* sqrt(3.8) =62V (highest measured value)
32*sqrt(4.1) = 65V (original based on maker's spec)

The motors will run 5~7 V higher then recommended voltage.

Will I be in any sort of problems?

Thanks in advance.

Ken

Last edited by KenC; Wed 18 November 2009 at 05:10..
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  #2  
Old Wed 18 November 2009, 05:33
Gerald D
Just call me: Gerald (retired)
 
Cape Town
South Africa
I don't think you will have a problem . . .

If your motors run a little bit too hot, then reduce the current setting on the drive.
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  #3  
Old Wed 18 November 2009, 07:38
aniljangra
Just call me: Anil #44
 
Delhi
India
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Quote:
Originally Posted by KenC View Post
I bought these 86HS9801 specs
It says the coils has 4.1mH

I measured the inductance between the wires & the results as follows

Coil A, 3.64mH, 3.67mH, 3.71mH, 3.67mH (Red-Yellow)
Coil B, 3.61mH, 3.46mH, 3.53mH, 3.80mH (Orange-White)
Coil C, 3.62mH, 3.42mH, 3.56mH, 3.77mH (Brown-Green)
Coil D, 3.65mH, 3.71mH, 3.72mH, 3.66mH (Blue-Black)

Ken
I'll trust the documented Inductance value as I think the inductance may vary with frequency (the freq used by you measuring instrument may be different).
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  #4  
Old Wed 18 November 2009, 07:47
KenC
Just call me: Ken
 
Klang
Malaysia
Anil, I'm using a DMM to measure, not sure what frequency the use though...

Gerald,
Thanks again. will have to remember keep a close monitoring on the heated motors.

I am also concern that the values varies greatly between coils & motors. Is that normal?
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  #5  
Old Wed 18 November 2009, 09:04
aniljangra
Just call me: Anil #44
 
Delhi
India
Send a message via Skype™ to aniljangra
I'm not an expert on this but i think Inductance is measured at 1Khz, rotor locked position. Anyway as Gerald said it doesn't matter here, just keep an eye and reduce voltage if motors seems overheating.
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  #6  
Old Wed 18 November 2009, 09:53
Gerald D
Just call me: Gerald (retired)
 
Cape Town
South Africa
Quote:
Originally Posted by KenC View Post
I am also concern that the values varies greatly between coils & motors. Is that normal?
The biggest variance is between the 3.42mH and 3.80mH measured values. The average value between those two is 3.61mH with a variance of 0.19mH to either side. That is only 5% . . . . . which I think is darn good!
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  #7  
Old Thu 19 November 2009, 01:31
KenC
Just call me: Ken
 
Klang
Malaysia
OK, inspired by gerald, I took a quick stats analysis with spreadsheet, I get standard deviation of 0.08 & a median of 3.65, that is +/-2.2%. I can ask any better then that.

This is the wiring diagram I received, want to be sure that I'm doing the correct thing.
stepper motor wire color.jpg
For half coil, use
1) coil A(red-yellow) & coil B(white-orange)?
2) it really doesn't matter as long as we take half of each phase?
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  #8  
Old Thu 19 November 2009, 01:44
Gerald D
Just call me: Gerald (retired)
 
Cape Town
South Africa
Quote:
Originally Posted by KenC View Post
For half coil, use
1) coil A(red-yellow) & coil B(white-orange)?
2) it really doesn't matter as long as we take half of each phase?
Quite correct on both points.
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  #9  
Old Thu 19 November 2009, 02:36
KenC
Just call me: Ken
 
Klang
Malaysia
Thank you for you reply.

Ken
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