LED burning at 277v circuit

tortuga

Senior Member
Location
Oregon
Occupation
Electrical Design
https://www.pge.com/includes/docs/p...ergystatus/powerquality/voltage_tolerance.pdf
All you could ever wanted to know about voltage range. But 291 is a hair above, or right at the very edge of the sustained utility voltage limit.
Still, LED ballasts that can not handle +/- 10% sustained are inadequate ballasts.
Interesting, on a side note do you have a link to the one in current use for Brazil/south America? Their voltage ranges have moved up, they now use a 220Y127 volt nominal system as and phased out 208V. But I dont think they did that at other commercial/industrial voltages like 480Y277.
Other than exceeding voltage limit (such as those caused by loose neutral), electronic ballasts are rather sensitive to surge and even the integral ballast on some disposable LED lamps have an MOV to protect its ballast from small line transients that can harm semiconductor parts. MOVs look similar to a capacitor, but they're not marked "C" on the board. https://www.edn.com/teardown-a19-led-bulb/ see figure 5.

Now, if you find a cooked MOV, that is often caused by over-voltage. So that's something to check on the fried LED ballast. A normal "surge failure don't usually cause the MOV to visibly cook.

Thread starter, you didn't post the other side of the failed board. Did you take pictures of the component side?
Looking again at his first pic, my guess is the phase conductors attach on the right, with the ECG on the lower right.
what burned appears to be a bank of 4 resistors in paralell, that perhaps connect to a trace of the ECG?

My guess is the MOV's would be really close to where the large pads are for the line conductors.
Would be cool to get an update on this. ledboard.png
 

hbiss

EC, Westchester, New York NEC: 2014
Location
Hawthorne, New York NEC: 2014
Occupation
EC
Looking again at his first pic, my guess is the phase conductors attach on the right, with the ECG on the lower right.
what burned appears to be a bank of 4 resistors in paralell, that perhaps connect to a trace of the ECG?

My guess is the MOV's would be really close to where the large pads are for the line conductors.
No idea, your picture is too blurry to see anything especially resistors burned. I would also need a CLEAR picture of the other side of the board to identify the components. Normally MOVs wouldn't have 3 leads.

-Hal
 

tortuga

Senior Member
Location
Oregon
Occupation
Electrical Design
Well I keep coming back to this one wondering what happened?
130 fixtures out of 800 I'd really like to know the brand at least.
Did the utility lower the voltage?
Was there a bad MWBC neutral?
and if 10 fixtures were looked at by MFR what did they say?
 

hillbilly1

Senior Member
Location
Atlanta,Ga
Occupation
Field coordinator/ technical support
Being a Target, it may have a small backup generator for the emergency lights, the ones I have worked on are non-SDS, but that one may be set up as SDS, with a four pole switch, and neutral and ground not properly bonded together at the generator. If one or more circuits on normal power got mistapped and use the generator neutral, it would go open when on generator power. Maybe the op will get back with what they found.
 
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