Is this an inductor?

Thread Starter

Mike Callahan

Joined Jan 6, 2009
2
This component apparently opened up and inhibited the startup of a power supply with line input of 24vdc. It almost has to be an inductor, but has no markings and the value is unknown. (Picture attached - centralp 003.jpg) A solid wire jumper was installed as an emergency fix and the supply works!
 

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Thread Starter

Mike Callahan

Joined Jan 6, 2009
2
Guess what! It worked until our customer powered it up under load and it popped a 2 amp fuse in the same circuit. We did some destructive testing and now it looks kind of like a wire wound resistor. Judging by the resistance measured from one end to the first accessible point inside the windings (about 3 Ω), we guessed the total resistance to be about 10Ω. I found a 15Ω, 3 watt wire wound resistor and installed it in the circuit to limit the powerup current. Not having any documentation on the rated load of this supply, I tried a 10Ω load resistor on all the outputs and the supply powered up loaded with no problems, even with a 1 amp fuse where the 2 amp fuse blew previously. Keeping my fingers crossed!
 

studiot

Joined Nov 9, 2007
4,998
Difficult to comment without a better idea where in the circuit the device was located.

There is a range of green ceramic coated wire wound power resistors available.

Low value wire wound resistors are also used for their low inductance as high frequency protection in Zobel networks, at high current.
 
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