Light bulb comparison

[JoeStillman]

More importantly you, like me, did not read the OP's question carefully enough.
He asked whether lowering the PF seen by POCO would decrease his bill. And the answer to that is a resounding NO. It would actually increase his bill slightly for the reasons we discussed. And if he were a commercial user it would increase it a lot because POCO does not like supplying power to low PF loads.

lakee911: There is nothing good about low power factor. It has only neutral or bad consequences, depending on what part of the whole power distribution you look at and to what level of detail. The combination of low and power in sequence gives many people the wrong impression of what it means. Low Power Factor has nothing to do with Low Power.

/me eats more humble pie, repeats to self; 'low power factor =bad, high power factor = good, lather, rinse repeat..."

Low power factor = high reactive load. Reducing reactive load is what I should have said.

 

[JDBrown]

I was always under the impression that W = PF * V * A. I had assumed (and we always know what that does) that in the case of a CFL, the low PF was simply the reason why it used less energy. But what you're saying is that the wattage is low and the PF is simply increasing the VA?

Let me ask this, if there was a magic widget that I could put on my service that would lower my power factor (opposite of power factor correction capacitors), would my bill go down?

To add to what has already been said, all other things being equal, if you decrease your power factor your Watts don't change but your VARs increase (which means your VA and Amps have increased).

Using your equation from above, Watts and Volts remain constant, so as Power Factor decreases Amps must increase proportionally.

 

[lakee911]

To add to what has already been said, all other things being equal, if you decrease your power factor your Watts don't change but your VARs increase (which means your VA and Amps have increased).

Using your equation from above, Watts and Volts remain constant, so as Power Factor decreases Amps must increase proportionally.

And if VA goes up, then I'll actually have more current on the wire than I think I have thus the greater I-squared-R losses, ya?

 

[gar]

131003-0900 EDT

lakee911:

Make your load a constant resistance with a parallel variable capacitor. Power is dissipated in the resistor, and none in an ideal capacitor. Thus, power to this load is a constant.

When the capacitor is 0 the PF = 1 and the average current is at a minimum value defined by the resistor. As you increase the capacitance the current increases and the power factor drops, and the losses in the supply lines increase.

.

 

[StarCat]

CFLs

CFLs

Highest and fastest failure rate of any " lightbulb " I have ever encountered to date....
As to the general devolution of many products which are poorly designed and " not " durable....these are at the bottom.
As to the design envelope, why would any sane person think that making it more narrow is going to help anything but selling more of them?

 

[ggunn]

Highest and fastest failure rate of any " lightbulb " I have ever encountered to date....
As to the general devolution of many products which are poorly designed and " not " durable....these are at the bottom.
As to the design envelope, why would any sane person think that making it more narrow is going to help anything but selling more of them?

I have been underwhelmed by their lifespan as well. It's great that they use less energy, but if I have to replace them as often as I would incandescents, where is the savings?

 

[JDBrown]

And if VA goes up, then I'll actually have more current on the wire than I think I have thus the greater I-squared-R losses, ya?

Exactly.

Highest and fastest failure rate of any " lightbulb " I have ever encountered to date....
As to the general devolution of many products which are poorly designed and " not " durable....these are at the bottom.
As to the design envelope, why would any sane person think that making it more narrow is going to help anything but selling more of them?

I have been underwhelmed by their lifespan as well. It's great that they use less energy, but if I have to replace them as often as I would incandescents, where is the savings?

Out of curiosity, what kind of underwhelming lifespan are we talking about? Only being involved in the design phase of construction projects, I don't often get to see things like lamp lifespan in the real world, so I have to just look at how often I have to replace them at home.

I have some CFLs (I think the brand was "Greenlite") that I bought at Big Lots and started using between 8 and 10 years ago. At this point they've started burning out, but 8-10 years seemed like a pretty decent lifespan to me. Of course, I have no idea how many hours that equates to, since I don't really keep track of how long each light in my house stays on (just the general, "Hey you kids! Turn off the lights if you're not in the room!").

My bigger concern with those CFLs is the way some of them fail. One of them burned out in my daughter's room a while back, and we didn't think anything of it -- there was still enough light from the other lamp to get by, after all. But then we started to notice that very distinctive hot/burning electronics smell in her room. After sniffing all over the room like a really awful bloodhound, I finally narrowed it down to the light fixture.

When I got up on a stool for a closer look, what did I find? The integral ballast on the CFL was severely discolored from heat, and there was a hole melted/burned right through it. Had I ignored the smell and left the switch turned on, I think it's likely that I would have had a house fire on my hands. After that, I remove CFLs as soon as they burn out.

 

[ggunn]

Out of curiosity, what kind of underwhelming lifespan are we talking about? Only being involved in the design phase of construction projects, I don't often get to see things like lamp lifespan in the real world, so I have to just look at how often I have to replace them at home.

I have some CFLs (I think the brand was "Greenlite") that I bought at Big Lots and started using between 8 and 10 years ago. At this point they've started burning out, but 8-10 years seemed like a pretty decent lifespan to me. Of course, I have no idea how many hours that equates to, since I don't really keep track of how long each light in my house stays on (just the general, "Hey you kids! Turn off the lights if you're not in the room!").

My bigger concern with those CFLs is the way some of them fail. One of them burned out in my daughter's room a while back, and we didn't think anything of it -- there was still enough light from the other lamp to get by, after all. But then we started to notice that very distinctive hot/burning electronics smell in her room. After sniffing all over the room like a really awful bloodhound, I finally narrowed it down to the light fixture.

When I got up on a stool for a closer look, what did I find? The integral ballast on the CFL was severely discolored from heat, and there was a hole melted/burned right through it. Had I ignored the smell and left the switch turned on, I think it's likely that I would have had a house fire on my hands. After that, I remove CFLs as soon as they burn out.

I started replacing incandescent bulbs with CFL's three or four years ago. I didn't keep a log, but many of them have already bit the dust. I also had one start switching between two levels of brightness every couple of seconds, and when I went to check that it was screwed in tightly, I burned my fingers (not badly - first degree) on the base where it attached to the tube. I replaced it.

 

[gar]

131003-2202 EDT

My experience with CFLs has not been bad. Overall life has been good. Those in recessed fixtures are in Kirland units and the bulb is horizontal so cooling is fairly good. In any of my units I do not need dimming and thus this big problem is avoided.

On the other hand I have two hallway areas with dimmers and incandescent bulbs. These are virtually never run very bright and the life is extremely long. 20 years or more for some of the bulbs.

For a dressing room night light, on 24 hours per day, I use a 757 pilot light run at about 1/2 nominal voltage (nominal is 28 V). Bulb in any reasonable time never burns out. Originally, 1960, bulb was rated at 20,000 to 50,000 hours at nominal voltage (I don't remember the value), but later reduced to I believe 5000 hours. Whatever, it is a long life pilot light, and at half excitation voltage, still sine wave excitation, it will last so long as to be of no concern. Also produces more than enough light. The transformer is a big power waster relative to the bulb.

.

 

[glene77is]

130929-0746 EDT

For my notes "Reading, Collecting, and Using DTE Smart Meter Data to Help Reduce Energy Use"
I have run some new comparison measurements of power and light intensity on samples of Incandescent, CFL, and LED bulbs.
See http://beta-a2.com/energy_c.html for a summary of the notes.

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Gar,
Thanks for another excellent "measured" Thread .
Over the years, you have provided much "measured" insight into our Electrical science.
It is often like going back to school.
GlenE77is