I have used a Biddle 57J Energized Winding Resistance Meter. Connect the motor
or transformer and you can take measurements while the device is powered.
Kevin
From: John Woodgate
Sent: Tuesday, December 19, 2017 1:18:02 PM
To: EMC-PSTC@LISTSERV.IEEE.ORG
Subject
Ask someone you don't like to put their finger in the way. :-)
John Woodgate OOO-Own Opinions Only
J M Woodgate and Associates www.woodjohn.uk
Rayleigh, Essex UK
On 2017-12-19 18:45, Wiseman, Joshua wrote:
I’ve done similar techniques. The only problem I’ve run into is
waiting for the motor
I’ve done similar techniques. The only problem I’ve run into is waiting for
the motor to stop spinning in the case of fans. The spinning can cause some
erroneous readings too.
Josh
From: John Woodgate [mailto:j...@woodjohn.uk]
Sent: Tuesday, December 19, 2017 1:18 PM
To: EMC-PSTC@LISTSERV.IEE
I made a box with a double-pole, double-throw switch, an appliance
toggle switch which is inherently break-before-make. This disconnects
the supply and connects the ohmmeter in about 0.2 seconds. It takes
longer to read off the resistance!
John Woodgate OOO-Own Opinions Only
J M Woodgate and A
I’ve used the rise of resistance method without problems. The challenge is
making the measurement before the windings cool off. The rise of resistance
method can be more challenging when you have a small winding that doesn’t hold
heat well. It is practically impossible to make the measurement th
Yes, there is a much better method. It measures the average temperature
of the whole winding, rather than the temperature at a particular spot.
IEC 62368-1 incorrectly says that the thermocouple method measures the
average temperature. You will find it explained in Annex E of IEC
60950-1. Incre
Hi Scott- very good questions. I have never used the change-of-resistance
method. I have always been able to get thermocouples in the windings (it
can change the winding shape slightly but if you use very thin
thermocouples and the motor size is reasonably large the overall effect is
negligible).
Scott, as far as I know, no safety standard requires you to embed the
thermistors. They can be placed on the surface of the winding. Then your
temperature limit is reduced from the UL/IEC insulation rated value. For
example, in IEC60335-1, temperature limit on Class B (130) insulation is
lim
I will be conducting the temp rise measurements on windings of AC motors for
electrical appliances such as washing machines, dishwashers, etc. It said the
thermal couple method is commonly adopted for safety assessment. I can
dismantle the windings and place the couples inside the windings usi
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