'dry testing' brushless motors - RC Groups
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Jun 02, 2008, 07:54 PM
homo ludens modellisticus
Ron van Sommeren's Avatar
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'dry testing' brushless motors


See
http://www.wattflyer.com/forums/showthread.php?t=35216

Vriendelijke groeten Ron
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Jun 04, 2008, 10:59 AM
Dirt Torpedo
Brian Click's Avatar
Good stuff there!

Another tip (I'd add it to the WF forum but haven't signed up there yet) is to use a DMM and terminating resistor (or small lamp) connected across a winding phase to measure the generated current...

Spin up the motor using a cordless drill and measure the voltage (AC of course), and note the reading. Then do the same for the other two phase connections, and compare readings.

All 3 measurements should be the same and if they're not - you have a shorted turn or missing / extra turn. Or your drill battery is dying between runs ;-)

You should also touch one wire to the motor's frame (to check for shorts to the pole piece) while doing each phase test; there should be NO change in the reading.

If you have an oscilloscope, you can use that as well, to look for distortion and/or amplitude variations in the waveform. Distortion indicates a shorted winding.

Amplitude variations indicate turn imbalances between poles and can even reveal weak magnets in the rotor and/or spacing (magnet to stator clearance) variations or a (badly) out of round rotor, assuming turns are known to be correct.
Jun 05, 2008, 06:53 PM
Registered User
vollrathd's Avatar
Brian
Would you mind if I copied your response to my 'dry testing' brushless motors thread, with proper credit given to you?

It would be nice to keep all the good ideas on one place.

Let me know, and thanks.
Jun 05, 2008, 06:57 PM
Registered User
vollrathd's Avatar
Hi Ron
The name "Kyle" is the company I worked for for 45 years before retiring. They are now part of www.CooperIndustries.com. That job took me to just about every state in the USA, plus around the world five times.

Now, its good to stay home, I've seen poverty that is beyond belief, saw electric power substations patroled by armed military folks with machine guns 24 hours a day, you name it. Saw dumb people nearly get killed by getting within inches of a 13,000 volt power line.

My real first name is "Dennis"!
Jun 05, 2008, 07:54 PM
homo ludens modellisticus
Ron van Sommeren's Avatar
Ok Kyle, next time it's Dennis

I think nobody would, or could, object if you used their ideas. With a proper reference/credit of course.

Vriendelijke groeten Ron
Jun 05, 2008, 10:08 PM
Dirt Torpedo
Brian Click's Avatar
Quote:
Originally Posted by vollrathd
Brian
Would you mind if I copied your response to my 'dry testing' brushless motors thread, with proper credit given to you?

It would be nice to keep all the good ideas on one place.

Let me know, and thanks.
Dennis - Yes, of course, and thank you for asking!
Jun 05, 2008, 11:00 PM
Registered User
vollrathd's Avatar
Will Do!
Aug 13, 2011, 11:20 AM
Registered User
Fourdan's Avatar
Hi

If you have an oscilloscope
it is also good to check the phase relationships (in addition to magnitudes)
Normally B/A = 120 deg and C/A = 240 deg

But for example :
If you observe B/A = 60 deg and C/A = 120 deg, phases are not correctly connected (reverse beginning B1, finishing B2)

Louis


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