large electromagnet testing
large electromagnet testing
(OP)
What is the best way to positively determine the health of a large electromagnet (8G wire, 300 turns)? Resistivity? Thanks all.
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large electromagnet testing
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RE: large electromagnet testing
One useful parameter would be to check the magnetic field it produces.
RE: large electromagnet testing
Hipot test
Coil resistance
Magnetic field
No single test 'positively determines the health'. It is possible to pass one of these tests yet not be safe to operate.
A bit more information would be reasonable and useful. That information would include and not be limited to
AC or DC design
Operating voltage
Operating current
Application
Air cooled or oil filled
Human contact or accessibilty
Physical size
Duty cycle
Mike
RE: large electromagnet testing
This electromagnet is wired in parallel with another electromagnet, and I noticed that it seems to be operating at higher current, relative to the other magnet, than it used to (using 89% of the total current vs. 78% previously, or 14% higher). It is difficult to replace so I need to be sure it is broken (internally shorted?) first. It operates DC, 100% duty cycle at up to about 50 amps. It is 8G square wire, 306 turns, 4.8" long by 3.2" in diameter. It is encapsulated in boron nitride containing epoxy and surrounded in circulating cooling water. It is part of a ion thin films deposition source. I have calculated its wire length and resistance based on the manufacturers data; and the current is about 14% high compared to calculated. What test do you recommend? What is "megger test"? Thank you.
RE: large electromagnet testing
The coil resistance should be measured of both coils when disconected from the system. It will need to be done with a much more accurate ohm meter than typically found in most multimeters. The coils should be left off say maybe over a weekend for this test. It is most important they be the same temperature.
A encapsulated coil is probably imposible to repair.
If the coils are not being cooled the same, the warmer one will draw less current.
The manufacturer should be able to tell you the coil resistence when original. Thst is the only way to know for sure.
Mike
RE: large electromagnet testing
Other than the increased power draw, is it causing any problems?
RE: large electromagnet testing
In the future you may also want to measure inductance and capacitance. Measuring such low resistance is difficult. Some motor shops will have high precision meters for this.
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