fluorescent lights and power factor issues? Will smart meters measure power factors?

ircoha

The background to this question is a debate on issues around CFL's and the fact that having all the bits combined makes them more wasteful and cause power factor issues.

In the halogen end of the business
in the GU10 fitting the traffo is in the bulb and all gets thrown out
In the GU5.3 the traffo is separate and lasts for several bulb-lifes.

The GU XX traffo, AFAIK, has no power factor issues.

All the compact CFL's I have seen are only as replacements for the GU10's and I have not seen a cfl equivalent for the GU5.3. Are they available?

There is a mix of ones with electronic ballasts or ordinary ballasts.

[what is the ballast in an ordinary full size FL: is it the white thingy that screws into the side of the fitting without removing the bulb or is it the 'traffo-like thingy' inside in the fitting?]

I have some full size ones for 25 years and have only replaced the tubes and the white thingy.

So in an ordinary full size FL, what bit causes the power factor issue?
does the power factor issue arise with the electronic ballast in the replacement CFL's?

A related concern is that the smart meter will detect the power factor requirement in each house and charge accordingly so we all move to CFLs as per the Gormley dictat and then get screwed
Thanks

MickLimk

Here's my 2c:

In an older 'long tube' style fluorescent fitting, the ballast is the transformer-like block that sits under the cover of the fitting. This is an inductor and it's primary functions are to provide a high voltage to start the lamp initially and to limit the current when it's running. The white thingy that is often accessible from the side of the light fitting is known as a starter and it's purpose is to short out the ends of the lamp(tube) at start up to preheat them before the lamp lights.

It is the inductance of the ballast that causes the power factor problems in fluorescent lights and to counteract this, most fittings contain a capacitor that should be sized to negate the effects of the inductor (ballast) in the circuit.

Say a typical CFL had a power factor of about 0.5 versus a regular bulb that has a power factor close to 1 (a purely resistive load). A regular incandescent 100w bulb produces roughly the same amount of light (lumens) as a 20w CFL. As of this moment the ESB bills us based on Watts so right now a CFL could produce an 80% saving on lighting costs.

If a change were made to bill us in KVAh instead of KWh, the figures for the incandescent and CFL would change to 100VA (100W / PF of 1) and 40VA (20W / PF of 0.5) respectively. This still implies a saving of 60% using a CFL over a regular bulb.

Electronic ballasts can be way better than the old inductor/choke style especially if they switch at a higher (10-20kHz) frequency. It is possible to get high efficiency CFLs with a power factor > 0.9 but I don't know how these compare cost-wise with those with a PF of about 0.5 or so. Maybe not a lot of difference now between and maybe these are becoming more main stream but I've never seen this info on the packaging.

I don't know the design of the smart meters that are supposed to be on the way, but measuring the power factor as well as KWh wouldn't be that difficult. The power factor can be calculated relatively simply by the phase relationship between the current and voltage. I think there have been cases where large industrial customers with a relatively poor overall power factor have a premium charged based on their PF. Changing to KVAh would effectively charge us for the distribution cost of our usage as well as the power we consume.

My thinking would be that as domestic consumers, there's very little we can do about PF in the home until it becomes something that's marked on the outside of electrical items that we buy. Is this something that's taken into account with energy ratings already?

fishdog

The background to this question is a debate on issues around CFL's and the fact that having all the bits combined makes them more wasteful and cause power factor issues

This is an interesting point.

Personally I think if we were all to sure energy saving lighting it would have very little impact on our overall energy consumption. Some time when I have a chance I intend on metering the lighting circuits of my house for a month just to see what percentage of a monthly ESB bill they represent. Very little of it I would imagine!

If you were concerened about the effect a light would have on power factor it may be possible to connect a capacitor in parallel with it at source (within the fitting or close to it, say in a coffin box in the ceiling void above the light). This would correct the problem. Ideally the ESB are looking for a power factor of 0.95 AFAIK. You would need to know the inductance of the light fitting to make this calculation. I am sure the manafactuer would supply this information. I would imagine that the load from these fittings is so small that it would make very little difference or this capacitor would be installed in the factory (or maybe it is???).