CFLs Take a False Hit

EDN is an electrical engineering magazine that goes way back. It gives general electronics info that usually only electronics engineers would be interested in. There is an article in the EDN on-line edition Powersource blog that is likely to be used in a way that is unrealistically critical of CFL light sources.

The issue at hand is the fact that because CFLs are not purely resistive devices, they exhibit a phase difference in their use of power. This results in what is called a Power Factor that is non-unity for CFLs(unity for resistive), in fact was measured at 0.45 to 0.5. This means that the power required to cover the phase difference can be as high as double the advertised rating, say 28.8 Watts required to be supplied in order to operate a 13 Watt CFL bulb. This doesn't mean that the CFL actually uses anymore than the 13 Watts, it means that the voltage and current availability to the CFL needs that amount in order to operate; the remainder is reflected.

This is said to be wasteful to the utility, which loses energy due to the resistive line drops incurred while the excess power is running around the grid.

But the problem that arises with such a statement is this: First, the overall power generation is still less than half that for 60 Watt filament bulbs. The idea that CFLs take "double the power" is misleading, because that power statement is based on 13 Watts, not 60 Watts. Second, I suspect that CFLs do not exhibit the standard inductive phase lag of wire wound devices, but probably exhibit a duty cycle that is almost a like a phase lead. If this turns out to be the case, then the extra power is complementary to the needs of inductive wire wound devices and is a sop for their reflected power. Unfortunately the engineering job was not done to determine the actualities.

Power factor is not a new issue. All motorized electrical devices exhibit power factors; probably more devices do exhibit non-unity power factors than don't. Washers, dryers, refrigerators, air conditioners and heat pumps... all the larger devices in a home except for resistive devices like heaters, cooking ranges, irons and toasters do have power factors.

CFLs have enough issues to make them worrisome without adding any bogus issues to the list.