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Anonymous Poster #1

Load Factor and Efficiency of LED Light

07/16/2020 2:54 AM

Is there any load factor of fixed LED light? Or is it always 1? Not dimmable. Suppose 100W LED.

Can a 100W LED light draw more than 100W from the source under any circumstances? Not dimmable.

Thanks.

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#1

Re: Load factor and efficiency of LED light.

07/16/2020 3:52 AM

An LED light is always accompanied by a driver that supplies the power required for the light...typically the power factor is between 0 and 1, with .9 being an efficient driver...An LED should not require more than 80% of the driver capacity for operation (with the exception of AC LED drivers)....A 100 watt LED means that the light is capable of drawing 100 watts or less...If it is over driven it will shorten the life of the light...

https://www.1000bulbs.com/pdf/understanding-led-drivers.pdf

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#2

Re: Load factor and efficiency of LED light.

07/16/2020 6:52 AM

<...Can a 100W LED light draw more than 100W from the source under any circumstances?...>

Yes, when there is a fault.

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#3

Re: Load Factor and Efficiency of LED Light

07/16/2020 10:54 AM

By "load factor" do you mean power factor?

If so,there is always a power factor involved if there is an inductor in the circuit.LED driver,A/C powered will have a very ,low power factor,near zero,due to the very low inductance of the driver's power supply.

Insofar as efficiency,there will always be less output than input power,and the rating of the LED is based on Input Power,but LED's are much more efficient than other currently available types of lighting.

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#4

Re: Load Factor and Efficiency of LED Light

07/16/2020 12:30 PM

There is the added confusion that many LED lamps are still marketed by wattage values for an incandescent to produce a similar amount of lumens of light. Thus a 100W LED may actually draw about a dozen watts of power but there are actual 100W LED, they're really bright.

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#6
In reply to #4

Re: Load Factor and Efficiency of LED Light

07/16/2020 4:59 PM

The LARGE print giveth,but the small print taketh away.

Mass marketing motto.

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#5

Re: Load Factor and Efficiency of LED Light

07/16/2020 2:24 PM

“Load factor” is not the same as “Power Factor”, totally different concepts. Load Factor is the ratio of peak load to average load; think of something like a compressor that runs continuously, but an unloader valve cycles on and off to allow it to compress only when needed.

Load Factor would not apply to something like an LED lamp. It’s either on or off. When on, it draws it’s rated power all of the time.

That said, the point of what “100W” means with LED lamps is very valid. Does that mean “lumen equivalency of a 100W incandescent bulb”, which is how many people market LED lamps but the actual watt draw will be somewhere around 13W if power, or is the LED driver actually rated for 100W input? If it is, that would make the lumen output roughly equivalent to somewhere around a 750W incandescent lamp. VERY bright!

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#7

Re: Load Factor and Efficiency of LED Light

07/17/2020 3:04 AM

There would seem to be one considerable brainfart in the original posting on this thread.

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#8

Re: Load Factor and Efficiency of LED Light

07/18/2020 7:16 PM

Most people, including electricians, do not realize that the driver (which supplies power to the actual LEDs) tends to draw a very large inrush current when first turned on. This inrush is while it charges its capacitors. Incandescent bulbs also have a very large inrush current when they are turned on (because the cold filament has a much lower resistance than the hot filament). However for incandescent bulbs the magnitude of the inrush current is lower than for LED drivers. When you change out an incandescent bulb or fixture and install an LED, the total load is reduced and the total inrush is also reduced.

If, however, you are designing a new application, you will put a greater number of LED fixtures on it because teach one draws a much lower operating current. When you do this there can easily be an inrush current larger than the instantaneous trip rating of the circuit breaker, if the lights are all turned-on at the same time. Since the lights are in different areas and are usually controlled separately, this inrush problem does not show up very often.

Therefore, to answer your question, if by "load factor" you are comparing instantaneous load when first turned on against continuous load, the load factor is probably closer to 6 or 10 (or more) for a fraction of a second, and is higher for typical LEDs than for incandescent lamps. Drivers for LEDs can be made with lowered inrush currents, so this problem will most likely disappear in a few years.

--JMM

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