Okay, so why does an AFCI trip during acceleration of variable speed motor with a MOV protected outlet strip between the AFCI and motor, but there's n o trip with the outlet strip removed, motor wired directly to AFCI. Must be some recovery issue with the MOV, and maybe there's a potential for variab le speed motor drives shortening the life of MOV protected outlet strips.
Wild guess: the MOV clamps when accelerating and the clamping action shapes the current waveform to fool the ACFI to think it is a high frequency arc?
Clamped sine has overtones...
Or the ACFI is sensitive
Cheers
Klaus
I think so too.
does the outlet strip have movs connected to the saftey ground pin?
may be an accumulation of leakage to ground and the ground fault portion of the acfi is tripping.
I'll look into it, but as I understand it the AFCI is not looking for a GND fault, it's looking for something like a line to neutral discharge similar to an arc through defective insulation.
or maybe the MOVs have nothing to do with it, simply the added length of wire changing a resonance.
m
I believe AFCIs are required to have ground fault detection at 50mA or less. It is typically 30mA. The idea is that an arc with a ground present may damage insulation and also involve a ground fault.
One of the manufacturers had UL test whether a "glowing connection" would cause a ground fault on a grounded receptacle. A "glowing connection" is a loose connection at the screw that produces a lot of heat, but is not (at that point) an arc. From memory, 25% or more caused deterioration that caused a ground fault trip.
The early AFCIs only detected at a current level that would see a "parallel" fault - line to neutral or ground. After about a year they would detect at a level (5 A?} that would detect a "series" arc (loose connection).
-- This email has been checked for viruses by Avast antivirus software. https://www.avast.com/antivirus
ElectronDepot website is not affiliated with any of the manufacturers or service providers discussed here. All logos and trade names are the property of their respective owners.