LED 4 foot lamps

[gary deinhard]

A manufacturing client is having issues with 5 rows of fixtures. 22 4 foot fixtures, 4 lamps across each, 5 rows.
He replaced all rows with LED lamps removing the ballasts. 277 volt. rows will not turn on unless a large current is running from a 480 volt machine .
We have checked voltage , 277 volt, added # 10 nuetrals to each circuit, checked all wire connections. no change to the behavior.
voltage is good at the beginning of each row but the row wont turn on.

 

[Flicker Index]

What voltages do you see across the terminals with and without 480v machines running?

 

[synchro]

We have checked voltage , 277 volt, added # 10 nuetrals to each circuit, checked all wire connections. no change to the behavior.
voltage is good at the beginning of each row but the row wont turn on.

When that voltage was measured were the lights connected to provide a load, or were they disconnected?
And are the lights being powered by all 3 of the phases, or just 1 or 2?

 

[gary deinhard]

When that voltage was measured were the lights connected to provide a load, or were they disconnected?
And are the lights being powered by all 3 of the phases, or just 1 or 2?

We measured voltage at the beginning of each row. Reads 277 volt to nuetral and ground. Its a three phase 4 wire system with one nuetral for three sperate circuits. We added nuetrals to each circuit thinking that was the problem. Still nothing . If we switch on and off the circuit breakers, turning off light circuits and then turning on o, we can get them to eventualy turn on. One row would not turn on but eventually came on by itself.

 

[gary deinhard]

What voltages do you see across the terminals with and without 480v machines running?

We read 277 volt to ground and nuetral for each breaker circuit. The Load, when they do come on is only 7.4 amps per row.

 

[hbiss]

Thinking that your LED replacements aren't rated for 277.

-Hal

 

[Flicker Index]

We read 277 volt to ground and nuetral for each breaker circuit. The Load, when they do come on is only 7.4 amps per row.

I was asking about the voltage values at the input of the fixtures acting out w/ and w/o "large current running" at a 480v fixture to help get some idea as to why it works why that load is on. You haven't provided the pair of values.

 

[gary deinhard]

Hi. The voltage at the beginning of each row of fixtures reads 277 volt to Nuetral, 277 volt to ground. With or without the large machine on.

 

[synchro]

A manufacturing client is having issues with 5 rows of fixtures. 22 4 foot fixtures, 4 lamps across each, 5 rows.
He replaced all rows with LED lamps removing the ballasts. 277 volt. rows will not turn on unless a large current is running from a 480 volt machine .

If all the lights are on when the 480V machine is running, if you turn off the machine do all of the lights still stay on or not?

Conversely, if you switch on the lights without the machine running, and at least some of the lights are lit up, does turning on the machine then make all of the lights work?

 

[gary deinhard]

If all the lights are on when the 480V machine is running, if you turn off the machine do all of the lights still stay on or not?

Conversely, if you switch on the lights without the machine running, and at least some of the lights are lit up, does turning on the machine then make all of the lights work?

All lights will stay on when the machine is not running. Phase A and B are the most problematic. My next step is to shut down the main switchgear and check all of the phases for tightness at the connections. Its a ILine Sq. D Distribution board.

 

[synchro]

All lights will stay on when the machine is not running. Phase A and B are the most problematic.

So apparently there's an issue getting the lights to initially turn on, but if they do turn on they will keep functioning.
This is just a WAG, but perhaps there are power factor corrrection capacitors on the 480V, and there is a transient voltage that possibly has some ringing/oscillation just as the lights are switched on. And this causes control and/or switching supply circuitry in the lights to not function properly at start up. A large load would be shunting power factor correction capacitors if they are present, and this load might be able to dominate the overall impedance so that any ringing when the lights are switched on could be less significant and allow the lights to turn on properly.

 

[gary deinhard]

So apparently there's an issue getting the lights to initially turn on, but if they do turn on they will keep functioning.
This is just a WAG, but perhaps there are power factor corrrection capacitors on the 480V, and there is a transient voltage that possibly has some ringing/oscillation just as the lights are switched on. And this causes control and/or switching supply circuitry in the lights to not function properly at start up. A large load would be shunting power factor correction capacitors if they are present, and this load might be able to dominate the overall impedance so that any ringing when the lights are switched on could be less significant and allow the lights to turn on properly.

Im not aware of any capacitors other than what might be on individual machines. The LED lamps are 277 volt, Made in China, not EnergyStar,
A Company called PARMIDA.

 

[synchro]

A manufacturing client is having issues with 5 rows of fixtures. 22 4 foot fixtures, 4 lamps across each, 5 rows.
He replaced all rows with LED lamps removing the ballasts. 277 volt. rows will not turn on unless a large current is running from a 480 volt machine .

The LED lamps are 277 volt, Made in China, not EnergyStar,
A Company called PARMIDA.

It sounds like you were not the one that re-wired the fixtures. If that's true, have you compared a fixture's wiring with the manufacturer's instructions? It should be straightforward, but there's a chance that something is not quite right.

Does the machine use a neutral from the 480V supply?

 

[LarryFine]

It almost sounds like the machine is acting as a rotary inverter.

 

[James L]

Im not aware of any capacitors other than what might be on individual machines. The LED lamps are 277 volt, Made in China, not EnergyStar,
A Company called PARMIDA.

Are they single rated 277v or universal?' I've seen a lot of universal voltage that are 100-265v

I'm with Hal, maybe they're not 277v tubes, even if they say they are.

Easiest thing would be to buy 4 different 277v tubes and try them in a fixture

 

[readydave8]

Parmida

I had trouble at one location with ballast bypass tubes, at random some would not light when switched on. Checked all splices in that part of circuit with no results.

Found out that switching adjacent row off and back on would make all lights in problem row come on.

"Solved" by changing ballast bypass tubes to hybrid (I've turned lights in that room on hundreds of times in the last 2 years and they've always all lighted)

At shop began to test problem tubes in new fixture, all came on, none were bad

My theory is that tombstones at job were old and not making good connection, turning adjacent row off and back on bounced electrons around (or maybe hex had been done but couldn't find wizard to confirm)

 

[gary deinhard]

Are they single rated 277v or universal?' I've seen a lot of universal voltage that are 100-265v

I'm with Hal, maybe they're not 277v tubes, even if they say they are.

Easiest thing would be to buy 4 different 277v tubes and try them in a fixture

The lamps are ARMIDA, T8 LED, 2200LM/AC120-277VOLT

 

[gary deinhard]

It sounds like you were not the one that re-wired the fixtures. If that's true, have you compared a fixture's wiring with the manufacturer's instructions? It should be straightforward, but there's a chance that something is not quite right.

Does the machine use a neutral from the 480V supply?

WE HAVE CHECKED THE WIRING. ACTUALLY THE MACHINE DOESNT NEED TO BE RUNNING, JUST TURNED ON.

 

[synchro]

I agree with James L that trying another brand of tubes in one of the fixtures could be worthwhile.

If it's reasonable to do with the existing wiring, disconnecting all but one fixture on a circuit could be done to see if that one fixture still has the same difficulty in turning on. If it then turns on OK repeatedly, it would indicate that loading from multiple fixtures is causing the problem to appear, but the tubes themselves are working.

 

[gary deinhard]

I agree with James L that trying another brand of tubes in one of the fixtures could be worthwhile.

If it's reasonable to do with the existing wiring, disconnecting all but one fixture on a circuit could be done to see if that one fixture still has the same difficulty in turning on. If it then turns on OK repeatedly, it would indicate that loading from multiple fixtures is causing the problem to appear, but the tubes themselves are working.

Thank you, we will try this.