Wire Insulation rating for DC

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cheeseweasel

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We have a debate on the insulation rating for the conductors to be used on High Voltage DC.
We have a braking resistor enclosure on the DC bus on a VFD. The DC bus voltage is normally 650VDC when the input power is 480VAC to the convertor of the VFD. When the load is overhauling or the drive is braking, the DC bus voltage increases and when it reaches 750VDC, the chopper module turns on and burns off the excess voltage (energy) in the resistors. This limit on the DC bus is 810VDC at which point the VFD will shut down to protect itself.

Should the insultation rating on the wire be 1000V? I have the customer questioning if they can use 600V wire as it is a DC application.
 

Cold Fusion

Senior Member
Location
way north
600V insulation would likely be okay. However, with out any other data than you have given, it wouldn't be my choice if I had to stamp it.

I'm curious as to what the mfg installation specs are. What does their book say? Or their engineering staff? I'm always real partial to following the mfg specs.

If no mfg specs available, another idea is to check any internal wiring on the DC bus. What is the rating on that insulation?

cf
 
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