How to Test DC motors?

Thread Starter

jpietrowiak

Joined Feb 22, 2009
5
How do you test DC motors with a meter. Is there anyway to test overall contact with the brushes. I've tested AC motors with a megger. Does the same apply?

Thanks
 

b.shahvir

Joined Jan 6, 2009
457
How do you test DC motors with a meter. Is there anyway to test overall contact with the brushes. I've tested AC motors with a megger. Does the same apply?

Thanks
:cool: I think a DMM (in ohms or continuiy test mode) would work fine for contact with brushes. A megger is always best for insulation test of machines.
 

Thread Starter

jpietrowiak

Joined Feb 22, 2009
5
I assume then checking to ground on the motor would be the same. What about between leads like on a standard motor? Also i heard someone say once that they connect all the leads together then perform some sort of test. I always on AC motors just test each lead to ground instead of trying to tie them all together. What are your thoughts?
 

jpanhalt

Joined Jan 18, 2008
11,087
I have seen DC armatures tested with a "growler." Here is an interesting link describing testing DC motors. The use of a growler is several pages deep.

John
 

Thread Starter

jpietrowiak

Joined Feb 22, 2009
5
Not sure I follow it completely. Where do you put your meter leads. Do you remove the brushes and put your leads into the whole? Perform tests from the wires? Leave brushes in and hold them there and test? or do you have to rip apart the entire motor to test?
 
Hi,

I have been working with DC motors ,drives etc for over thirty years. Whilst using meter and megger meters check out the continuty and grounds it cannot really check a DC motor out propelly. What I have done is actually built a test jig to apply actual voltages to both field and armatu,re. The motor must be uncoupled from the load. As a result, the motor turn. However, one must be very careful in doing this test.

How about those SCRs? Do not use a megger on SCRs!!!. An ohmeter can find somefaults. Again, I have built a jig to test in an active mode and by turning a pot , the scr can be made to be turned on ligtly or heavily.

Passively checking items is not 100% acurate.

Douglas
 

GetDeviceInfo

Joined Jun 7, 2009
2,192
you would test your insulation with a megger. You can check your continuity with an ohm meter. For brushes/commutator, your best check is visual. A high speed or heavy duty motor can see problems where the rotor conductors are crimped into the comm segments. If the motor is dissasembled and you have a growler available, you can test for shorts within the windings.

Aside from that, then you want to ensure your windings are connected properly, be it series, shunt, or compound. From there you would go on to load/no load testing to evaluate your winding configuration and drive performance.
 

MaxHeadRoom

Joined Jul 18, 2013
28,619
Lagacy thread but:
The best way to check brushes and armature is by inspection.
For a simple tests the applied rated voltage to test if reaches rated rpm, also the back feeding method for generated voltage for volts/rpm.
For a shorted armature test the Growler is an optimum way.
Google growler.
Max.
 
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