Hello everyone,

i have problem with 3 led bulbs:


This ceiling lamp has power factor 0,264 (with only 3 led bulbs 230V 50Hz AC, 6W, e27).
Other parameters:
-0,24 A RMS
-15,8 W Active Power
-60,72 VA Apparent power
-58,6 VAR Reactive power

How to easily and cheaply repair the power factor? Changing the voltage to DC isn't possible.

I calculated that I need a 3.5uF capacitor - should it help?
What are the other ways?
Thanks

 

Why are you concerned about the power factor?
Generally you are not charged for reactive power in a residence.

 

Scientific approach

 

Scientific approach

Unless your power consumption is high enough for your utility company to assess additional charges for reactive power, it's not worth the bother. You'd be negating any certification the device already has.

 

lighting fixtures are bought separately, and light bulbs separately. I am interested in the scientific approach to the issue of power factor and its improvement (theory).

 

To provide a circuit to correct the power factor you need to know whether the reactive power is lagging or leading, and your measurement doesn't show that.

 

Reactive power is negative (-58 var) so leading (φ<0).

 

Reactive power is negative (-58 var) so leading (φ<0).

Okay.
Since a capacitor also provides a leading phase, you would need an inductor to correct the power factor.

 

There is nothing practical you can do. The load is highly non-linear because it is a rectifier followed by a "filter" or "smoothing" capacitor. The peak of the current is in phase with the peak of the voltage. The poor power factor is due to the fact that the current from the line is zero throughout a significant portion of each half cycle. Power factor correction for this type of load is usually done by using high-frequency switching, essentially with a boost converter, to force the instantaneous current to be directly proportional to the instantaneous voltage while inversely proportional to the longer term average voltage.

 

Hello everyone,

This ceiling lamp has power factor 0,264
.
.
Thanks

Can someone tell me what would cause the PF of LED lights to be so low? As far as I know, there are no Inductors.

 

Can someone tell me what would cause the PF of LED lights to be so low? As far as I know, there are no Inductors.

The LED bulbs have ac/dc converter inside.

Okay.
Since a capacitor also provides a leading phase, you would need an inductor to correct the power factor.

Do you know any books on this topic? Schematics? Anything that will improve my knowledge on this topic?

There is nothing practical you can do. The load is highly non-linear because it is a rectifier followed by a "filter" or "smoothing" capacitor. The peak of the current is in phase with the peak of the voltage. The poor power factor is due to the fact that the current from the line is zero throughout a significant portion of each half cycle. Power factor correction for this type of load is usually done by using high-frequency switching, essentially with a boost converter, to force the instantaneous current to be directly proportional to the instantaneous voltage while inversely proportional to the longer term average voltage.

Do you have any schematic or information about high-frequency switching? How to use it in these lamps?

Thanks
Szymon