Using a Dimmer Switch with LED Bulbs
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- Опубликовано: 19 янв 2016
- www.keysight.com/find/IntegraV...
Using a light dimmer with an LED bulb can be a bit confusing. Only a few dimmers are rated for dimmable LEDs and dimmable LED bulbs can vary greatly. In this video we will look at how the typical dimmer works along with a couple varieties of dimmers. In addition we will look at two different dimmable LED bulbs. An IntegraVision Power Analyzer is used to view the voltage, current, and power going into and out of the dimmer switch. IntegraVision allows the real time display and analysis of power waveforms.
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A very nice presentation.
As of January 2019, finding compatible LED bulbs and dimmers is still a bit of a crap shoot.
The Institute of Electrical and Electronic Engineers (IEEE) has made a first-pass attempt to quantify Lamp modulation and flicker
with Specification IEEE 1759-2015.
Lamp buzzing and Radio Interference - other than dimming lamps with a variable transformer or variable DC supply, one good solution to both 120VAC dimmed lamp buzzing and dimmer RFI is a "Debuzzing Coil". It also helps buzzing of 120VAC non-dimmed lamps.
I recently converted a number of 120VAC light fixtures from incandescents and CFLs to LEDs. Some are dimmable. I thought the new Lutron LED-compatible (trailing edge, FET?) dimmers would interfere less with my favorite AM Talk Radio stations than my original Lutron (leading edge, TRIAC) dimmers. No significant difference.
I tried various types of Radio Frequency Interference (RFI) filters to no avail. Then I discovered Debuzzing Coils, specifically intended to reduce light bulb and fixture buzzing. They're simply installed in series with the load, or if a dimmer is used, in series with either "hot" (BLK or RED) lead of a dimmer. Doesn't matter which. By slowing a dimmer's ON or OFF transitions, they also reduce AM Broadcast Band RFI from 30 to 40 dB. Typically a 10 milliHenry, toroidal (donut-shaped) ferrite inductor, they come in 100, 150, 300 and higher Wattage ratings. Lutron and a number of manufacturers sell them. They're on ebay.
Agency-approved Inductors aren't cheap, running anywhere from $25 to $100, depending on Wattage (Load Voltage x Current). Higher Wattage inductors are larger, to accommodate larger wire and a larger ferrite core, to prevent magnetic saturation. A 150 Watt Inductor is about 2 inches in diameter and 3/4 inch thick. It can always fit somewhere in a multi-gang junction box. Larger Inductors are up to 4 inches in diameter and won't fit in a single-gang junction box.
If you're electromagnetically inclined, with the right test equipment, you can buy your own cores, enamel-coated Copper wire and wind your own. Please understand you're dealing with National and Local Electrical and Fire Codes when installing non-Agency-approved devices in your junction boxes.
Interesting, thanks for the effort!
very nice video, I would like to ask,
I have 7 cob leds with serial connection and ıt needs 180v max power, I used dimmer and full bridge reclifier and they work great, but I didnt put open long. it can be damage leds in long time?
Great video except you didn't show the trailing edge dimmer with the LED bulb !
What are the electronics in the led doing specifically? I would assume measuring the voltage waveform to detect the desired brightness
what happens when you use a transformer? i have a "non dimming" led and the transformer seams to dim it just fine. Will it catch fire or anything? The transformer is still sending a sine wave and a clipped sign wave or any kind of weird pulse. The amperage draw seems to be scale-able with the voltage. dims to about 50v then cuts off. dims pretty linearly. bulb is 120v type and does increase amp draw but no noticeable increase in brightness above 120v. Tested to 140v
Great Video! What were the bulbs used??? Thank you for visualizing this on your scope, (as you would say, Keysight drool-factor has increased by "X's")
I was shopping for dimmers when I found your video. I chose one (Leviton Lutron DVLV-600P) but looking through all of the companies documentation: there is no mention of "forward" or "Reverse" Phase control. I suppose that if this method becomes accepted there may be marketing to reflect this.
Josh, Soon after I made the video the hardware store stopped selling the inexpensive LED light bulbs. The price of the high quality lights has dropped significantly. Most dimmers are forward phase. The reverse phase dimmers were designed to be used with low voltage halogen lights. I went to a couple stores in order to find one. Today, LED bulb designers have to design their dimming bulbs to be compatible with forward phase control.
now I want that machine instead of the dimmable led
hey they only cost 28 grand
very good video the last thing you want to hear on your ham radio shack or shortwave radio is to hear a buzz on your receiver because a LED bulb buzz
Most new LED lights require a ELV (electronic low Voltage) noise reducing dimmer. If you are having issues using dimmers on LED lights save your self a lot of headaches and just purchase a Viribright LED dimmer switch. ELV 300VA 2 way or Single Pole. for like $16 on amazon
but what is the theory behind a 'dimmable led'? as most leds work on a constant DC voltage? and most bulbs in the base include an expensive 120vac to dc converter. I'm trying to understand this.
Hi. Thanks for the great video. Why does a dimmable LED (inexpensive) pulsates (constantly varying brightness) when connected to a generator? I tested it with two different dimmers and one showed smooth result and the other had pulsing output. How does a dimmer switch effect the output for the driver?
Ahmed Nousand Were you using an LED bulb like the ones shown in the video? And, was the generator (Variac) used to reduce the voltage? A traditional light bulb can be dimmed by reducing the voltage. However an LED bulb has a minimum voltage at which it will function correctly. The LED bulb has a very inexpensive circuit used to convert the AC voltage to a DC current. One of the design assumption of the converter is a minimum voltage.
The generator used in the facility is operating in Island Mode. I checked the same LEDs on different facility running on Grid Power or other Diesel Generators. There was no pulsing effect visible.
The LED is with a 24 watt dimmable driver and another is a 35 watt dimmale driver. I used Siemens Universal Dimmer (20-500VA).
Can you post a video showing waveform when the input voltage is not stable? Like when the input is an improper voltage and frequency.
Ahmed Noushad It sounds like the problem is low voltage. The light bulbs plus the dimmer have a minimum operating voltage. The dimmer should have a specification for line voltage +/- 10%.
But it works fine on utility supply. It is more like varying brightness (100 lux variation) rather than flickering.
Very interesting!
+Kent A. Vander Velden Thanks.
I am wanting to install dimmable high bay LED lights I see cheap LED lights for sale but they do not say dimmable the more expensive ones say dimmable what makes them different ? and the price is quite a bit more like 10x more is it the driver transformer i am sure the leds are the same
Scott Lundy. Dimmable bulbs use slightly more sophisticated electronics in the bulb. The bulb manufacturers charge a premium for dimmable bulbs. I would make sure the bulbs are marked dimmable before putting them on a dimming circuit.
What happens when you put a capacitor on the dimmer load?!
+Tradie Trev Great question. When the voltage changes suddenly a capacitor pulls a lot of current. The LED bulbs use a capacitor in their driver and you can see the current spike at 5:50 (middle waveform). I also noticed the reverse phase control switch which is designed for a capacitive loads had a limited range - it did not go past 90 phase 3:29.
Why does the power factor change so much on the LED bulbs as you dim it?
Led is a semi conductor that’s why! Micro radio activity due to resistance on a ac current but also allows conductive polarization 😮
What about spikes of current ? Is that dangerous or damaging ?
mba2ceo The spikes are very common on dimmers - they do not contain much energy and do not cause problems.
What happens with dimmer signal after full bridge rectifier?
Mr .soj When a sinewave is applied to a full bridge rectifier the output is a completely positive signal - a series of humps. A dimmer will remove a piece of every hump. A capacitor is used after the rectifier to create a dc signal. The capacitor is the biggest part inside an A19 lightbulb which has additional circuity to create a current source for the LED.
I dim my dimmable led bulbs by converting the AC to DC and vary the DC voltage to the bulb.
Frenchie. Very cool. Another method is to use a constant DC voltage but occasionally switch it off. This method is referred to as pulse width modulation (PWM). Using the same voltage creates the same color from the LED. The amount of light or brightness is determined by the length of time the voltage is applied versus not applied. Hopefully, a future video.
some dimmer switches make a humming noise with led bulbs .....
luciu constantin The buzzing is very common, caused by an inexpensive part inside the switch. The AC power in your house has a frequency of 50/60 Hz - you can think of the humming as "current music".
i am the 100th liked.
Lun Liu Appreciate it!
This is a great promotional video for your KeySight analyzer. However, the point of this should be to actually SHOW THE DEVICES UNDER TEST IN REAL TIME. Simply showing the waveforms defeats the purpose, in my humble opinion.
The devices under test were common dimmer switches that are used in houses. All of the DUTs performed as expected. I was really interested in seeing the phase control as had only read about it and looked at illustrations. In fact one of the illustrations incorrectly describe forward phase control. I found it interesting to be able to see the voltage, current and how they combined as power in real time. Phase control is really a neat solution for dimming lights.
Great video. I'll change my thumbs down when you list the devices tested.
Rotating dimmer Leviton 6602, Luton DVCL-153P, and a Luton DVLV-600P (reverse phase dimmer).
Great video. I'll change my thumbs down when you list the devices tested.