Affect Of CFLs On Power Quality?

Electric_Light

CFLs are starting to get more common and while they save energy, they contribute to uncorrectable power quality problem, how much? I have no idea.

Environmentalists talk about much kWh and tons of CO2 would be saved if every incandescent lamps were to be replaced with CFLs.

In real world, if all incandescent lamps were replaced with CFLs, how much effect would it have on power quality?

A 25W CFL makes about the same light as a 100W light bulb. While it only use 25W of power, get a bunch of them togther and they piss off the distribution transformer far more than an equal number of 25W incandescent bulbs would and you'll see many restaurants have switched their seating lamps with CFLs.

CFLs look just like a computer power supply on the supply side. Power factor is horrible, but voltage and current are almost in phase. Lousy power factor is caused by the distorted current waveform, therefore, the utility can't correct it with a capacitor bank.

Recent data I have taken of a Maxlite 25W 41060 CFL:

V 123.1v
A:0.356A
P =23.5W
PF =0.533
Cos phi = +.945, slightly leading
current crest factor: 3.85

THD: 160%
3rd harmonic: 80%
5th harmonic: 69.3%
7th harmonic: 50%

Get about 100 of these lit up, as you'd see in a restaurant, they'll have about 4.4kVA of demand and unless the transformer is K-rated, the word is that you have to oversize by a factor of three to accommodate the highly harmonic currents, so you'd be taking up about 13.2kVA worth of distribution resource to provide 2.35kW. You can make CFLs look like a resistive load with an on-board PFC, but that shatters the possibility of $1/ea CFLs.

Any input?

frenchsparky

you did bring up pretty good challange with this one,..

I know most screw in CFL are very lousy with PF [ power factor ] they are about .50-.70 range which that is very common with cheap screw in CFL's but there are some good preium screw in CFL's which they have very good PF in there i heard but i did see few but not sure if excat answer most good one will dailed in about .90 or so PF.

but unforetally speaking of harmonic this is getting more common issue now it dont matter if in Redentail area or Commercal area at all.

[ i know you will mention about the haromic on 1Ø system but with true singel phase it seems cancled most of it but if you have 1Ø feed off from 3Ønetwork it will show up some degrees just like 3Ø system ]

PFC will help correct some situation but not always the case.

but properly sized netrual will useally slove some of it.

but let get back to the topic for a sec related to the CFL's

but with the extrenal ballasted type normally they are high PF rated ballast [ it is common with electronic unit unless you got one of the POS then it will be low PF regaurding if electronic or mag ballast ]

most electronic i know they have .90 PF but THD's kinda mixed bag they are anywhere from 10% to much as 50% or more some case but right now i did not get a chance to check some of my catalog books to get some details but if i have time i will make a comment on later posting.

Merci, Marc

Electric_Light

Major commercial buildings don't use many screw in CFLs and their external ballasts are high power factor, having >0.98 in most cases.

The uncorrected ~0.50 PF type are not permitted and they're sold as "residential use only".

Some 120v supply is obtained from 208/120 3ph system and 3rd harmonic adds up and overheat the transformer.

Any electronically ballasted lamps having a PF > 0.9 has an integral PF corrector.