Paddle fan light LED problem

[bluecollar84]

My paddle fan I bought came with
Incandescent light bulbs i swapped them out with dimmable led bulbs and I have an dimmer that works with leds. But they won’t dim for some reason when all three led bulbs are in the fan . If I swap out one of the bulbs with incandescent bulb I can get the two led bulbs and that one incandescent bulb to dim. Does any one know what my issue is? Thanks


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[LarryFine]

It's still an incompatibility between the dimmer and the LED bulbs. The incandescent bulb loads the dimmer so the output voltage drops. Most dimmable bulbs have a list of compatible dimmers, or the manufacturer can tell you.

 

[gar]

180210-1915 EST

bluecollar84:

You need to know how things fundamentally work and run bench test experiments.

For your experiments you need an adequate oscilloscope, associated equipment, and components. Further you need knowledge about electronic circuits, and components.

First, learn how to use a scope, limitations, and how you can get into trouble. What may be called ground or chassis on the scope front panel may loosely or tightly connect to the the AC power cord EGC. So you can not connect the probe ground lead to something that is not isolated from the electrical system ground, neutral, EGC or hot line.

Sync your scope horizontal time base to the AC line. Adjust time base to show one full AC cycle. Use a scope with at least two input channels. With a 10X probe connect this probe to the AC hot from the dimmer. Take the ground lead off of the probe so it touches nothing. Use an isolated current probe to measure dimmer output current. This can be in either the hot lead or return lead to the load. A DC-AC Hall sensor current probe is probably the best to use.

Now you can look at the voltage and current waveforms as you work with different loads, and adjust the dimmer control.

With your existing dimmer and LED bulb you will find the waveforms don't respond well to the adjustment position. Now try a single incandescent. Then the incandescent in parallel with your LED.

Next find a three terminal dimmer (meaning it requires a neutral). Probably has more than three wires. Requiring a neutral means more than just having a grounding wire. It means the dimmer actually requires an input of both hot and neutral. This type of dimmer requires the AC input voltage to power the electronics independent of load or dimmer adjustment position. Use this dimmer in your test.

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[gar]

180211-1221 EST

I know of no other way than an oscilloscope or equivalent to study this type of problem.

If you don't have a scope, then what do you do? Find someone that does.

If you have a well equipped IBEW training center with people interested in this type of problem, then see if they will run experiments with you.

Otherwise find friends, junior colleges, or high schools with appropriate equipment, and see if you can generate interest with them in experimenting.

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[ramsy]

180211-1221 EST

I know of no other way than an oscilloscope or equivalent to study this type of problem..

1) Flip the switch, usually on remote-control battery compartment, to select dimmable lamps.

State energy codes have resulted in new watt-limiting switches being integrated into ceiling fans, usually with dimmer-compatibility switches integrated at remote controls.

2) Another option is 3rd party light kits, usually missing watt-limiting controls.

 

[Dennis Alwon]

I have seen similar issues. I am guessing there is a current limiter in the fixture that may be causing the issue. Try removing it.

I have seen similar issues with cfl's where an incandescent was needed otherwise the bulbs would glow even when the switch was off.

The current limiter is really a guess as I can't think of another reason if as you say the dimmer is compatible with the dimmable led's

 

[kwired]

It's still an incompatibility between the dimmer and the LED bulbs. The incandescent bulb loads the dimmer so the output voltage drops. Most dimmable bulbs have a list of compatible dimmers, or the manufacturer can tell you.

I have run into situation where a dimmer on the compatible list still doesn't work very well with the LED. I think they have a way to go in perfecting dimming of LED's.

 

[gar]

180212-0858 EST

For an electronic dimmer to work it needs two things. Power for the electronics, and phase (timing) information from the AC input voltage, not current.

Most dimmers are two wire devices for cost and simplicity of installation. Thus, these work on load current, not a good technique. Can be made to work fairly well with an adequate resistive load. Other loads can be a big problem. LEDs that are screw in replacements for incandescent bulbs generally don't look anything like a resistive load.

If a dimmer is a three wire dimmer, meaning it requires a neutral and hot input, it can derive power from the AC input voltage to power the electronics, and obtain AC voltage phase information from the input with no output load at all. In turn this means, to a large extent, that turn on time in the cycle can be held constant for a fixed position of the dimmer control independent of load.

A three wire dimmer will provide the most compatibility with LEDs that are supposed to be dimmable

With a Triac or SCR switch a very inductive load can cause problems even with a three wire dimmer.

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