ptonsparky
Tom
- Occupation
- EC - retired
Hopefully this link works as intended.
Copied from another Forum I watch.
Yes, it is somewhat of an advertisement, but it does have some educational value for those of us that need it.
gfci & VFD
- Thread starter ptonsparky
- Start date
Hopefully this link works as intended.
Copied from another Forum I watch.
Yes, it is somewhat of an advertisement, but it does have some educational value for those of us that need it.
kwired
Electron manager
- Location
- NE Nebraska
- Occupation
- EC
I encountered a coin operated washing machine in a HUD funded housing complex that started tripping the GFCI that I had added because their inspecting people wanted the GFCI's since it was current codes to have them. So not having GFCI was obviously not a solution and of course their appliance repair guy says something must be wrong with the GFCI. So now it becomes my problem to solve what is going on.
Front load washer, would start cycle- fill with water and as soon as it drum would begin to move when it got to that point of cycle it tripped GFCI.
I plugged it in via a two to three prong adapter and it would run. We weren't going to leave it that way, was just a part of trying to decipher the issues. Their inspectors wouldn't allow it to be that way anyway when they do come around periodically.
When I took the back cover off to take a look inside I noticed a broken housing on this limit switch that normally would have it's actuator pressed in when the back cover is installed. It turns out it closes contact when back cover is removed and connects the EGC from the otherwise electrically isolated motor to the frame of the appliance. This allowed the high frequency leakage in the motor to have a return path if the cover were removed. I suppose the idea is it is not a shock hazard when the cover is on but should the cover be off then the motor is bonded and it will continue to run if not on a GFCI.
At the time I couldn't really find any specific details about this with on line searches, I could find the replacement part in appliance repair parts sites but no explanations of any kind about how this worked and kind of had to figure it out on my own.
I did encounter another washer one time since then that was also tripping GFCI it was plugged into. It also had electronic driven motor control but no back panel switch. One of first things I did on that one was also to plug it into a two to three wire adapter just to see if it would run that way - it did. Since it had no grounding isolation switch I ended up isolating the grounding wire to the motor and it then worked. That's how I left it figuring it was GFCI protected so shouldn't really be a user hazard. Why it did work without tripping then started tripping, IDK. Maybe they withheld information? It definitely was not a new machine, but maybe was new to them? Been a while but IIRC they were running it on an extension from a non GFCI protected outlet before I got there.
Front load washer, would start cycle- fill with water and as soon as it drum would begin to move when it got to that point of cycle it tripped GFCI.
I plugged it in via a two to three prong adapter and it would run. We weren't going to leave it that way, was just a part of trying to decipher the issues. Their inspectors wouldn't allow it to be that way anyway when they do come around periodically.
When I took the back cover off to take a look inside I noticed a broken housing on this limit switch that normally would have it's actuator pressed in when the back cover is installed. It turns out it closes contact when back cover is removed and connects the EGC from the otherwise electrically isolated motor to the frame of the appliance. This allowed the high frequency leakage in the motor to have a return path if the cover were removed. I suppose the idea is it is not a shock hazard when the cover is on but should the cover be off then the motor is bonded and it will continue to run if not on a GFCI.
At the time I couldn't really find any specific details about this with on line searches, I could find the replacement part in appliance repair parts sites but no explanations of any kind about how this worked and kind of had to figure it out on my own.
I did encounter another washer one time since then that was also tripping GFCI it was plugged into. It also had electronic driven motor control but no back panel switch. One of first things I did on that one was also to plug it into a two to three wire adapter just to see if it would run that way - it did. Since it had no grounding isolation switch I ended up isolating the grounding wire to the motor and it then worked. That's how I left it figuring it was GFCI protected so shouldn't really be a user hazard. Why it did work without tripping then started tripping, IDK. Maybe they withheld information? It definitely was not a new machine, but maybe was new to them? Been a while but IIRC they were running it on an extension from a non GFCI protected outlet before I got there.