Powerfactor of LED Lamps

They're DC. The power factor is 1.

Or do you mean the power supply that is AC?

GA

True, but has anyone checked the mains versions?

I have loads of 230VAC ones with the GU10 base connector, they are AC......

My personal take (guess really) that they are probably more "capacitive", so may actually "improve" the PF of any normal installation.....I see no inductance inside opened LED lights, but with SMD that may not be completely true.....

Just a thought!!

http://www.ecnmag.com/products/2011/08/power-factor-correction-techniques-led-lighting

This is one + 1,519,000 more hits on google.

The oscilloscope images from this article demonstrates my point about the harmonic content and not the power factor will be the problem that ubiquitous LED lighting will produce. The CFL current draw waveform looks similar to a sine wave but the current is in phase with the voltage waveform. The current waveform of the LED circuit shows a leading current draw (peak current happens before peak voltage) that charging a capacitor will produce. This current spike looks nothing at all like the voltage sine wave.

Great link, thanks.

Most LED lamps are "plug in", they come with a built in power supply.

Therefore the pf or power factor would be the connected load. Since it is not a pure resistive load ( due to the power supply ) power factor correction is built in in the control ic. In well made units.

The cheaper one are usually Constant voltage with a resistor for current control.

IMHO The power factor loading an LED assembly will impose onto the grid is the "red herring" problem they will affect onto the grid. The non-linear load of these supplies and diodes will produce much higher harmonic content to the currents in the grid. This will increase the core losses in the power distribution transformers and some what from skin effect of the transmission lines for the same amount of power delivered. Fortunately the efficiency loss will be accompanied by a reduction in total power drawn so this effect will probably just be an academic exercise at first. Eventually this will have the consequence of MV/LV transformers overheating at lower total power levels.

DC doesn't vary, there is no reactance

Quite true, which is why the problem lies in the power supply circuitry that drives the LED and not the LED itself.

My narrowboat is 12vdc. With an inverter to supply 230vac for equipment not available in dc format.

I've always wondered why we can't find more appliances with a DC alternative feed. I know that a few manufacturers provide this to cater to boat and camper owners but nearly every device in the home uses DC. And a lot of the AC to DC supplies just barely do the job for any specific device.

The best DC supplies you will find on the market (for your average home) are typically used for personal computers. They provide your 0.95 to 0.99 power factor depending on loading, etc. And for the various levels above or below your standard level there is always the DC-DC converter that has a high efficiency rating.

Maybe we'll get there some day. I believe that it will take an effort from some big companies to get that ball rolling.

Well, it is a conspiracy to have all those loose ends waving around in AC, isn't it?

Or mainly speaking, it is just more profitable for the power generators and distributors.

I totally agree with your concept. Nothing bad at all about DC circuits at close range, although the higher power ones might need larger conductors even within a house?

Most of the LED lighting I have installed over the last 5 years has been rated at .8 PF.

Some that I have not elected to buy is rated well below the .8 PF and is not an option to purchse for my applications.

A significant amount of LED fixtures lose efficiency due to overheating issues usually related to poor design, cheap components, and power issues.

Buyer beware!

LEDs (components) and fluorescent lamps (tube only) have some similarities in their current vs. voltage curves: a zero or small current at lower voltages, a steep increase in current at some voltage threshold. A sinusoidal applied voltage will cause a "lagged" current, which a PF meter will see as low-PF.

Early economy-lamp ballasts used to show a low PF. Nowadays the current consumption shows a high frequency current (rich in harmonics) with a nearly sinusoidal envelope, hence a PF close to 1.

SPS circuits for LED lamps should benefit from prior experience with CFLs.

LEDs have a higher efficiency with pulsed current as compared with pure DC.

So, this power factor rating is right on the box?