Electronic Ballast Failure
Electronic Ballast Failure
(OP)
thread248-278233: Electronic Lighting Balasts
We are still experiencing ballast failures even after installing 2 pole motion sensors on our 4 lamp T8 fixtures.
I'm thinking that because each ballast has two hots and no grounded supply conductors and the 2 pole motion sensor opens up both L1 and L2, the energy in the lamps has no place to disipate other than to circulate in the ballast internals.
So I'm thinking an MOV would be in order. So my question is;
2 MOVs per fixture, L1 to ground and L2 to ground.
or
1 MOV across L1 to L2.
Your thoughts please.
We are still experiencing ballast failures even after installing 2 pole motion sensors on our 4 lamp T8 fixtures.
I'm thinking that because each ballast has two hots and no grounded supply conductors and the 2 pole motion sensor opens up both L1 and L2, the energy in the lamps has no place to disipate other than to circulate in the ballast internals.
So I'm thinking an MOV would be in order. So my question is;
2 MOVs per fixture, L1 to ground and L2 to ground.
or
1 MOV across L1 to L2.
Your thoughts please.





RE: Electronic Ballast Failure
Keith Cress
kcress - http://www.flaminsystems.com
RE: Electronic Ballast Failure
We added a three phase transient voltage surge suppressor to the lighting panel as well and it seemed to reduce the failure rate, but didn't halt the failures.
RE: Electronic Ballast Failure
I have experienced loss of a client's ballasts in these cases, in which lightning (even just nearby) was probably the culprit. Your MOV suggestion at the fixtures is worth a try. The possibilty of energy traveling from the ends of the circuits back toward the panel is real, so that the TVSS at the panel can't deal with them until they arrive there.
If you at least partially clamp the voltage between the phases and between each phase and ground at each fixture, it might save them.
Good on ya,
Goober Dave
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RE: Electronic Ballast Failure
Your motion sensor switches cause no problems. They're just like light switches, and they have built-in time delays so they don't short-cycle. The fluorescent lamps do not store energy, so there is none to release when they are extinguished. They appear as a resistance to the ballast, albeit one that decreases after starting. Any damaging energy must be coming from the incoming power (or equipment ground, if it has some impedance due to distance from the service entrance).
Good on ya,
Goober Dave
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RE: Electronic Ballast Failure
How would I go about measuring the ground impedance?
RE: Electronic Ballast Failure
You mentioned that these ballasts are on a 208/120 service. Is there a chance that some device is switching off the primary of the transformer on a routing basis? Or is this addition subject to frequent power outages that don't happen on the origninal building? Interrupting the primary of a transformer can send a good bit of energy down the secondary conductors... Otherwise, I'm stumped. I would go from there to a power monitor if it's worth the effort (or just try the 3-MOV experiment).
I enjoy chasing transients. It can be frustrating, though.
Good on ya,
Goober Dave
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RE: Electronic Ballast Failure
After countless hours chasing transients etc. Starting dealing with the manufacturer trying to get information, found out only so many of these fittings could be installed on one mains Tx. Why? each ballasts produced a certain amount of a certain harmonic, the cumulative total was causing the ballasts to blow.
May be something similar? Maybe start asking questions of the manufacturer.
RE: Electronic Ballast Failure
CBravo; Get someone in to instrument and assess the harmonics on your distribution. It shouldn't take long as you have a static situation.
Keith Cress
kcress - http://www.flaminsystems.com
RE: Electronic Ballast Failure
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If we learn from our mistakes I'm getting a great education!
RE: Electronic Ballast Failure
Let us know what you find.
Good on ya,
Goober Dave
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RE: Electronic Ballast Failure