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Residential Well VFDs and LED flicker.

Merry Christmas
ptonsparky

ptonsparky

Tom
Location
NE (9.06 miles @5.9 Degrees from Winged Horses)
Occupation
EC - retired
Pump installer called me with some questions with the VFDs they are using on residential homes. Single phase in three out and some can also operate 2 wire pumps. I haven't seen details yet.

Issue at the moment is when the pumps kick on the LEDs blink or flicker. FWIU Franklin makes a filter in the $700 range.
We briefly discussed LED sensitivity to VD. Adding ferrite rings and the super cheap split ones offered on Amazon.

When grounding was brought up, I mentioned adding rods would do nothing. Apparently, not so in his experience. The devil will be in the details but apparently he drilled a hole in the basement floor, added a rod, and bonded directly to the drive. Flicker stopped. IDK if an EG to the line side of the VFD is there or not. I have been invited to look at a couple of homes with the issue including the with the one with the added rod. Worse yet is some homes are not bothered at all.

Any thought as to why a driven rod would help the situation?
 
ptonsparky

ptonsparky

Tom
Location
NE (9.06 miles @5.9 Degrees from Winged Horses)
Occupation
EC - retired
It is Franklin 2 wire in/out drives giving the problems. Pump installer thinks one in five gives flicker issue. They set me up with a drive and pump motor to play with today. Optional two wire control starts motor at 35 HZ and ramps up in 3-4 seconds. VD is .5 with Motor load only. No Pump. IIRC it’s been determined here that .5 is enough to cause the dimming/flicker on some dimmable LEDs. It didn’t bother my shop non dimmable. Visit to a job site later this week.
 
ptonsparky

ptonsparky

Tom
Location
NE (9.06 miles @5.9 Degrees from Winged Horses)
Occupation
EC - retired
That was fun. Lights never flickered once, no matter what load we cycled. Connected the EG as it should be and removed the connection to the supplementary rod.

I accused the owner and pump guy of smoking ditch weed but they assured me of their sobriety.

Can't fix what doesn't appear to be broken.
 
Last edited:
ptonsparky

ptonsparky

Tom
Location
NE (9.06 miles @5.9 Degrees from Winged Horses)
Occupation
EC - retired
Just what, not why.

Back yesterday and met with pump installer & Franklin Field rep who brought an older Franklin filter with him. The lights had started to blink again while connected to the branch circuit EG a week or so ago. I rigged up a 3 way switch so we could easily alternate from EG to isolated ground rod for easy comparison. Definite difference. Filter worked. A new version was going to be ordered and installed. In this house only the kitchen LEDs were affected.

Went to next house where I was going to watch while their EC did the checks. He couldn't make it, so I brought the meters out again.
Simpler. All the lighting was affected. About a 3 volt drop at start of the pump. SE conductors were typical Al conductors for 200 amp service. I suspect the POCO transformer is @ minimum. Filter made no difference when Field rep installed it.

The filter was interesting in how it could work for different systems and different voltages. The input filter had about a 10% voltage drop.
 
ptonsparky

ptonsparky

Tom
Location
NE (9.06 miles @5.9 Degrees from Winged Horses)
Occupation
EC - retired
NEC Inspector said:
So the ground rod did eliminate the flickering? Or just reduced it?
Click to expand...
Appeared to eliminate it. I didn't include the third option which would have been no connection to either. :oops: I should have.
I am not advocating the removal of a properly installed EG. It was the solution the pump installer came up with and partially why I was called. He knows better. The EG was connected when I left and they were going to suffer with flickering lights until the new part came in.
 
T

Tommy1776

Member
Location
SC
Occupation
Industrial Electrical Maintenance, AAS, CW
Residential well pump using a Franklin water pump VFDs =random LEDs to flicker, what is the name plate data for VFD & pump?

Tommy
 
ptonsparky

ptonsparky

Tom
Location
NE (9.06 miles @5.9 Degrees from Winged Horses)
Occupation
EC - retired
I used the three way before the filter was installed. Power in. I also inserted my meter inline to measure amperage. Milliamps. Rod had about 84, EG about 240. IDR exact values but would expect more with the EG. Motor and conductors to it megged 200+M at 500+volts.

Filter had the EG connected as it should.
 
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