Pulsing Lamps

[augie47]

All the LED lamps in the dwelling pulse when the washing machine is running. (Separate circuits, all voltages fine).. Solution ??

 

[coop3339]

This is an interesting problem probably caused by voltage drop from the draw of the washer motor. I guess it could also be small spikes or bad waveforms caused by the motor changing directions repeatedly? Do they change directions or is the direction change geared? In any case it is repeated loading and unloading. One fix may be a larger service and service lateral. This would reduce the voltage drop but many times it could also be from a small or overloaded utility transformer. Another idea may be a large surge suppressor on the service and at the washer machine. Still better would be LED drivers that have some filtering and a capacitor to smooth out the voltage changes over time so they are no longer perceivable. The drivers probably don't have these or they are very small due to cost and increased failures from the caps.

I guess some filtering could also be done in the washer power supply. I wonder if this is still a problem with higher quality appliances?

 

[ptonsparky]

Solution, put a minimum load on each lighting circuit. An Inc lamp or one of those dealy bobs I can never remember the name of sold by Lutron IIRC.

1st question is it a new problem or always been there?

 

[ptonsparky]

Has anyone tried putting a run capacitor on a cord and plugging it into the the receptacle feeding the offending appliance?

 

[coop3339]

Has anyone tried putting a run capacitor on a cord and plugging it into the the receptacle feeding the offending appliance?

I tried this a long time ago for a similar issue with low voltage dimmers and it didn't work. There were multiple LV transformers working circuits of LV lights in a large kitchen on many different switches. The problem was that when any set of lights was switched on or off the other sets would blink. I assumed this was caused by the inrush/spike on the transformers so I added caps to each transformer circuit thinking the caps would hold up the voltage and absorb the spike during the time the other transformers had inrush. looking back, I think the problem was due to the LV dimmers not being able to handle the spike/dip when the other transformers energized. I think the best fix would have been in the dimmer design not necessarily trying to control the distortion at the source. With this said, it is certainly worth a try but ultimately I think the problem is with the LED drivers.

Anyone know if these drivers are just a constant current DC source or do they provide pulsating current for heat reduction or something?

It would be interesting to see if a power drill or vacuum cleaner turning on and off would cause a similar problem. Or for that matter the refrigerator or an air conditioner.

 

[winnie]

I suspect that the problem is with the LED drivers interpreting high frequency noise as a dimming signal and adjusting their output.

Different LEDs might solve the problem, or a good noise filter (on the LEDs or on the offending appliance) might help.

Drivers are often some combination of constant current, or constant current for max output combined with PWM for dimming.

Jon

 

[augie47]

I suspect that the problem is with the LED drivers interpreting high frequency noise as a dimming signal and adjusting their output.

Different LEDs might solve the problem, or a good noise filter (on the LEDs or on the offending appliance) might help.

Drivers are often some combination of constant current, or constant current for max output combined with PWM for dimming.

Jon

any suggestion on a filter ??

 

[Little Bill]

I had something similar on a house. Difference was it wasn't all LED lights. Customer noticed the light in the fridge would pulse when the washer was going. I found several lights that would do it. I was seeing voltage fluctuation but didn't find any loose connections. I called the POCO and they finally discovered a splice they had made underground that was bad.

Might be worth a call to POCO to check their end.

 

[Little Bill]

any suggestion on a filter ??

You might try a ferrite choke on the washer cord. They don't cost much and are easy to install. Might be worth a try.

 

[synchro]

It could help to try an incandescent bulb.

If it also flickers then a momentary voltage drop on a panel bus is likely causing it. This can happen when the tub or agitator reverses and causes the motor to draw a burst of current. If an incandescent flickers, then it might help to try an incandesent bulb on both a L1-N circuit and a L2-N circuit (but not on the washer circuit itself, at least for this test). If a bulb that's powered from the opposite phase of the washer circuit is momentarily brightening during the flickering, that would indicate that it's caused by a voltage drop on the service neutral or its connections. You might need to have two bulbs on opposite phases side by side to distinguish a brightening from a dimming effect if the flickering rate is relatively high.
Testing using a relatively large L-N load such as a portable heater could be done on the washer circuit to see how that affects the L1-N and L2-N voltages on other circuits, and to determine if resulting voltage changes are reasonable or excessive.

If an incandescent does not flicker very noticeably, then it's very likely that noise coming from the washer is the issue, particularly if it has an inverter drive / VFD. Then as Jon mentioned, you could try different LED bulbs including dimmable and non-dimmable ones. If that doesn't help then a lowpass filter could be an option.

 

[Flicker Index]

Place the LED lamp on the same circuit as a portable fan. Those that have a shaded pole motor. These 1/75hp or so motors have hardly any inrush current but they make one mean inductive kickback. Jiggle the fan's switch repeatedly. It's the "pop" sound it might induce on a nearby speaker.

There are two basic causes for light output disturbances. One caused by lack of electrical inertia and one caused by ballast getting confused by spikes.

 

[kwired]

Has anyone tried putting a run capacitor on a cord and plugging it into the the receptacle feeding the offending appliance?

Wouldn't the capacitor just become a load when connected to an AC supply. One with a leading power factor but still just a load as far as how it interacts with other items other than it would exchange VAR's with inductive loads instead of letting them totally be exchanged with the source. Applying right size capacitor to the DC side of the LED driver would have better results - but this is why you pay more for better designed LED equipment. Most LED's that are direct replacement for an incandescent lamp are built pretty cheaply.

 

[Flicker Index]

Wouldn't the capacitor just become a load when connected to an AC supply. One with a leading power factor but still just a load as far as how it interacts with other items other than it would exchange VAR's with inductive loads instead of letting them totally be exchanged with the source. Applying right size capacitor to the DC side of the LED driver would have better results - but this is why you pay more for better designed LED equipment. Most LED's that are direct replacement for an incandescent lamp are built pretty cheaply.

Just like disposable built-in socket base ballast vs $20+ T8 ballast.