Surge Suppressor maintenance

[mgookin]

Has anyone ever heard of doing surge suppresor maintenance?

We get hit by lightning very often; we are on the edge of the Everglades in the lightning capital of the USA. It's not uncommon for us to get hit several times in one day during season (we're in season now). A week ago lightning took out two 150kVa xfrmrs and a few pieces of our equipment after coming through our 3p suppressors at the MDP's (we have 2 x 3p services, each with 3p Eaton/ Cuttler Hammer surge suppressors) plus suppression via UPS at most, but not all, equipment.

We manufacture outdoor light controls and we use the biggest MOV in the industry. I know from our own testing and from manufacturer's specs that a MOV will take a first hit at a given Joules rating, then be limited to a lower Joules rating on subsequent hits, etc. It causes the MOV to expand & fracture.

So I'm thinking that since we take so many hits, I should open up those 3p suppressors at our MDP's and checck the MOV's inside. Anyone agree?

And couldn't I parallel more MOV's in there? Each of our two services are 120v 1p & 208v 3p giving us 3 legs and a neutral. A MOV across one leg & the neutral absorbs the transient on that leg.

We have upwards of $1MM in robotics and none of that has ever been damaged. We shut off all machine line breakers when the line is not running. But it's inevitable that we will take a big hit with that line running and there's not enough whiskey in the world to drink away the problem which would accrue if that line gets taken out by lightning. Ultimately I'll have a 3p UPS but that's probably a year out due to funding. MOV's are cheap and we get them by the pallet.

Am I making sense?

I know that a big enough hit his not going to be absorbed by anything. Our customers come in with pictures of light poles split right down the middle. And we give them a free replacement control anyway.

We're already bonded to the hill. As an ESD facility we have a conductive floor which is bonded to the roof bar joists. We drill, tap and bond everything religiously to cause the potential to get as close to zero as we can. In considering doing this "suppressor maintenance" I'm just trying to be as diligent as I can.

 

[petersonra]

SPDs purchased these days usually have some indication when they have failed, a visual indicator and/or a switch. Check those periodically. Not much more you can do IMO.

I do not know if putting multiple SPDs in parallel does anything for you. It does help out the SPD manufacturer for certain.

My personal opinion is that the concern over surges in general is unfounded. The reality is that a direct strike will kill you no matter what and with something less than a direct strike you may not even know it happened.

Surges are a risk you can mitigate to some extent, but the risk cannot be eliminated.

My guess is shutting off the power to your equipment every day will do it more harm over time than all the surges you might see.

The kind of bonding you are describing is for static control and has little to do with protection from surges.

 

[robbietan]

SPDs purchased these days usually have some indication when they have failed, a visual indicator and/or a switch. Check those periodically. Not much more you can do IMO.

I do not know if putting multiple SPDs in parallel does anything for you. It does help out the SPD manufacturer for certain.

My personal opinion is that the concern over surges in general is unfounded. The reality is that a direct strike will kill you no matter what and with something less than a direct strike you may not even know it happened.

Surges are a risk you can mitigate to some extent, but the risk cannot be eliminated.

My guess is shutting off the power to your equipment every day will do it more harm over time than all the surges you might see.

The kind of bonding you are describing is for static control and has little to do with protection from surges.

agree here. it would take some doing to generate the voltage needed to "test" these MOVs. having an indicating light built in is better.

 

[mgookin]

Each suppressor has indicating lights; one per phase. That's especially helpful when we take a hit that only blows one phase of a tranny. It also has an audible alarm.

But those indicating lights are probably only going to trigger when it goes to zero. What I'm concerned about is wear.