LED Troffer Lights Flicker

geno555

Member
Location
70118
Occupation
Director of Plant Ops
We have 6 LED ceiling lights in the elevator lobbies on 3 out of 8 landings that flicker when the elevator runs. When the elevator is idle they do not flicker.
TK Elevator said nothing in there scope could cause this to happen.
Our in house guys checked and tightened all connections from the 12th Floor service panel to all the devices. Our trusted outside Electrician checked too. I installed different LED fixtures and that was worse. The lights went on and off fully instead of just flickering. Has anyone else had this problem?
 

geno555

Member
Location
70118
Occupation
Director of Plant Ops
Have the electrician check the voltage drop when the elevator starts, likely the motor starting current causes a sag and you notice it with the LEDs.
Got it, I think we did check that but certainly doesn't hurt to double check.
 

gar

Senior Member
210813-1637v EDT

geno555:

You need to develop an understanding of your loads of concern, the LEDs, and of your instrumentation equipment.

An LED alone is a very well definable device. It does not flicker if current to it is constant. An LED light bulb or tube is not likely a simple device or circuit. Thus, all sorts of possible problems may occur with source voltage changes.

Some LED bulbs I have played with driven from a Variac, an adjustable sine wave source, have shown a tendency to have a superimposed oscillation on the current at certain input voltages.

There are some CREE bulbs that I have played with that have relatively stable light output over a substantial range of input voltage. They also seem to show no flicker with a pulsed input voltage change.

Instrumentation may have some relatively long response times, and therefore, may not indicate short input changes. An oscilloscope may be required in some cases to see a disturbance.

You should do some bench testing of the LEDs to see how they respond to various voltage changes.

.
 

geno555

Member
Location
70118
Occupation
Director of Plant Ops
Absolutely agree that LED devices are not simple. The drivers vary in sensitivity widely. Attempting to save money on inferior less expensive can be a costly mistake. We will look into testing with shorter response time if needed.
 
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