Flickering LED

[ndan305]

Hello, we just completed LED light installation in a building and the lights would flicker for a bit when the motor on the gas/dx HVAC units turn on. What could be causing the issue and is there any way to fix it?

 

[ptonsparky]

Voltage drop.
Anything from and including increased POCO transformer and wire size all the way to the HVAC equipment.

You need to take voltage measurements to determine which areas need to be addressed first.

 

[ndan305]

Voltage drop.
Anything from and including increased POCO transformer and wire size all the way to the HVAC equipment.

You need to take voltage measurements to determine which areas need to be addressed first.

How is that possible? The building had fluorescents and was retrofitted with LEDs so the load should have decreased. Are LEDs just more sensitive to voltage drop? Is there a capacitor or something that can be added to eliminate the increased current draw when the HVAC motors are turned on?

 

[ptonsparky]

How is that possible? The building had fluorescents and was retrofitted with LEDs so the load should have decreased. Are LEDs just more sensitive to voltage drop? Is there a capacitor or something that can be added to eliminate the increased current draw when the HVAC motors are turned on?

Yes, that sensitive.
Capacitor, possibly.

 

[ptonsparky]

We've put PFC capacitors on cooling units for milk. IDK why that couldn't be done for three phase HVAC units. Measure the PF and add PFC to get you up to .9 or better.

 

[Flicker Index]

Hello, we just completed LED light installation in a building and the lights would flicker for a bit when the motor on the gas/dx HVAC units turn on. What could be causing the issue and is there any way to fix it?

Did whatever that was there flicker? If it's due to a genuine voltage drop, incandescent lamps would flicker as well. If it's not voltage drop, it could be transients (spikes or notches) causing the LED ballast to glitch out.

 

[Flicker Index]

We've put PFC capacitors on cooling units for milk. IDK why that couldn't be done for three phase HVAC units. Measure the PF and add PFC to get you up to .9 or better.

It would have no effect on starting/stopping transients.

 

[ptonsparky]

Adding the PFC will help with VD. May or may not help with flicker.

 

[ndan305]

Did whatever that was there flicker? If it's due to a genuine voltage drop, incandescent lamps would flicker as well. If it's not voltage drop, it could be transients (spikes or notches) causing the LED ballast to glitch out.

It was not noticeable before if it was flickering. The LED retrofit should have reduced overall electrical load, not increase it.

 

[ptonsparky]

The power supply for LED is totally different than a florescent. You did reduce the load but you installed something that can be more subject to voltage variation. You need to determine if it is VD. That is the easiest to check for.

 

[gar]

230228-2126 EST

ndan305:

Get a Cree 10 W LED, actual load is about 9.5 W. Connect this Cree bulb at the end of a piece of #18 rip cord about 50 ft long. The loop length ( 100 ft ) will be about 0.6 to 0.7 ohms. Also put a duplex outlet at the bulb location. At the bulb location plug in a 120 V 1500 W heater with a switch.

A 1500 W heater at 120V is about 12.5 A. The voltage drop from a 1500 W load on 50 ft #18 loop is about 8 V. Note that 12.5 A is too high a current for #18 copper, but for a short time it is not a problem, a few seconds. Does the Cree bulb flicker from turn on and off of the of the load
resistor. My test indicated NO.

Do the above test and see what happens with your present bulb, then repeat with a Cree. Report back.

.

 

[SSDriver]

Cheap LEDs have really bad flicker issues if everything isn't perfect. What brand of LED. Try a different brand in a few spots if possible