VFD lightning protection

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I have a public water supply that we do the electrical maintenance for. The building has three vfd's, two for booster pumps to provide pressure to the town and one for the well pump. Yesterday we had an electrical storm and it killed the well pump VFD and two water level control relay's ( these take readings from probes in the well.) This is the 2nd time this has happened and seem's to only effect the well pump controls and vfd.. I would like to know of a good product that I could use to protect both the line side and the load side of the VFD
 
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Jraef

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Electrical Engineer
I have a public water supply that we do the electrical maintenance for. The building has three vfd's, two for booster pumps to provide pressure to the town and one for the well pump. Yesterday we had an electrical storm and it killed the well pump VFD and two water level control relay's ( these take readings from probes in the well.) This is the 2nd time this has happened and seem's to only effect the well pump controls and vfd.. I would like to know of a good product that I could use to protect both the line side and the load side of the VFD
Line and load reactors on the VFDs and a good lightning arrester on the line side at the service entrance. Nothing will protect your drives from a direct hit, but this will help with the line surges and stuff coming back on the ground plane through the motor connections on lightning strikes that are just in the vicinity.
 

tom baker

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Here is Mike Holt once said regarding SPDs
"You get what you pay for
More is better"

My pump stations are 480 with a 480 x 120/240 lighting transformer. I install a Leviton 42277-DY3 on the primary, ($400) or if its got a lot of electronics, then a 52277-DY3, ($1500). The 52277 DY# has massive MOVs and replaceable modules
Then on the 120/240, a Leviton 42120-001 ($400). I use the impedance of the transformer to reduce the surges.

I used to get a lot of failed power supplies on equipment, and that has gone away with using SPDs.
Some one may mention grounding, didn't want to go there, as with the N-G bond at the service most surges go back to the utility, the SPD basically shorts the lines together and sends the surge back.

I have lost two 42277-DY3 in car pole accidents, probably due to sustained overvoltage.

All quality SPDs, including Leviton, have some kind of end of life indication, as the MOV has a finite life. The MOV is an open at low voltage but then at say 140 volts shorts out diverting the surge.

Leviton is not the only quality brand, there are others, I go with what works, and availability.
 
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petersonra

Senior Member
Location
Northern illinois
Occupation
engineer
I have a public water supply that we do the electrical maintenance for. The building has three vfd's, two for booster pumps to provide pressure to the town and one for the well pump. Yesterday we had an electrical storm and it killed the well pump VFD and two water level control relay's ( these take readings from probes in the well.) This is the 2nd time this has happened and seem's to only effect the well pump controls and vfd.. I would like to know of a good product that I could use to protect both the line side and the load side of the VFD

well.....

you can't really protect against lightning strikes. You can protect against some of the surges they can produce.

as another poster mentioned you can use SPD and reactors to reduce the magnitude of the surges seen by the equipment.

most modern power supplies are far more surge resistant than they were a decade ago. so replacing old power supplies with new ones may help.

you might also want to make sure that your system is a solidly grounded wye system rather than a delta system, that also helps limit voltage excursions. most VFDs these days come with MOVs on the input side. they are somewhat susceptible to surges on delta type power supplies because the MOVs are tied to earth ground. some VFDs allow you to remove these MOVs from the input if you do not have a grounded WYE input.

you may also want to consider an isolation transformer. the more magnetic lines you can get in the way of a surge the more it is attenuated.
 
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