Can a low voltage event damage a 1000w HPS ballast fixture reducing light output?

[Mike Dewan]

A friend lost power at their grow facility for several days. They have 1000w HPS fixtures. When power came back initially it was under voltage to normal voltage to under voltage. After this event the output of the fixtures now is approximately 50% of what they were. How can the ballasts still be functioning?

 

[don_resqcapt19]

I approved this post as it is not asking for how to information.

 

[GoldDigger]

A friend lost power at their grow facility for several days. They have 1000w HPS fixtures. When power came back initially it was under voltage to normal voltage to under voltage. After this event the output of the fixtures now is approximately 50% of what they were. How can the ballasts still be functioning?

Unlike motors, which will try to draw the same power from their source, causing the amperage to rise as the voltage drops. a ballasted HPS fixture, once it has started, will look like a negative impedance (the lamp itself) in series with a fixed inductance to limit the current.
So the current, and therefore the light output, will go down as the voltage goes down. This by itself will not harm either the lamp or the ballast.
But at some point the fixture will not start, which may cause strain on the ballast and/or the lamp depending on the type of starting circuit used. And at some lower voltage the lamp will drop out even after it has been started at a higher voltage.

 

[gadfly56]

Unlike motors, which will try to draw the same power from their source, causing the amperage to rise as the voltage drops. a ballasted HPS fixture, once it has started, will look like a negative impedance (the lamp itself) in series with a fixed inductance to limit the current.
So the current, and therefore the light output, will go down as the voltage goes down. This by itself will not harm either the lamp or the ballast.
But at some point the fixture will not start, which may cause strain on the ballast and/or the lamp depending on the type of starting circuit used. And at some lower voltage the lamp will drop out even after it has been started at a higher voltage.

Would you expect the loss of performance to be permanent, as I think the OP is suggesting?

 

[kwired]

I'm not as certain about HPS but several times in the past ran into metal halide luminaires that had reduced light output if the capacitor was bad.

 

[tortuga]

A friend lost power at their grow facility for several days. They have 1000w HPS fixtures. When power came back initially it was under voltage to normal voltage to under voltage. After this event the output of the fixtures now is approximately 50% of what they were. How can the ballasts still be functioning?

Are you sure all the issues are resolved did anyone actually check that the incoming voltage is withing normal range using a multimeter?

 

[Flicker Index]

A friend lost power at their grow facility for several days. They have 1000w HPS fixtures. When power came back initially it was under voltage to normal voltage to under voltage. After this event the output of the fixtures now is approximately 50% of what they were. How can the ballasts still be functioning?

Solid state ballasts are like glass. They can last decades but can be damaged/destroyed instantaneously from abuse. I would guess that semiconductors in the active PFC front end have failed from power surge. I've seen some 120-277v T8 ballasts that fail to operate or malfunction at 120v, but operable on 240-277v (but PF no longer corrected).