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Compact fluorescent lamps and power quality

Peter Van den Bossche on February 27, 2008 | 4444 Views | 10 Comments

One aspect that is rarely touched in the discussion about compact fluorescent lamps and the ban of incandescent lamps: power quality.

Have you ever seen the shape of the current absorbed by a compact fluorescent lamp? It just looks horrendous, far away from  a nice sinus, thus loads of harmonics!

If the use of such lamps is generalized, power quality may suffer, and addtional energy losses will occur.

One should also take this aspect into account. Proposed ban of incandescent lamps never seem to mention it, and also neglect several other aspect such as the overall cradle-to-grave LCA of the lamp. For light fixtures which are very lightly used (such as in domestic cellars, storerooms, etc), the energy saving of a compact fluorescent will never offset the cost of the lamp, and the overall environmental cost will likely be higher than when using an incandescent for such purposes. 

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10 Comments

#1 by Luke Fishback on February 28, 2008 at 11 p.m.

Interesting post.  Where can I find these current absorption profiles?

For a little more analysis of the cost of CFLs and some actionable advice for selecting which lights to replace with CFLs, this may be helpful: http://visibleenergy.blogspot.com/2008/02/which-bulbs-to-replace-with-cfls.html
In the interest of full disclosure, this is a link to my blog. 

#2 by Peter Van den Bossche on February 29, 2008 at 2:30 p.m.

I did a measurement today on a typical CFL rated 16W, this gave:

U=233 V

I= 0,11 A

S=25,2 VA

P=15,9 W

Q=19,5 VAr

PF=0,633 leading

Current harmonics:

1  100%

3   78,2%

5   45,6%

7   18,1%

9   11,7%

11 12,6%

13  9,4% 

15  6,7%

Total harmonic distortion on current: 94,6 % ! 

#3 by Rodrigo Juan Hernández on February 29, 2008 at 4:20 p.m.

Hi Peter,

             I totally agree with you about the high impact over the power quality. Nobody tells the people the complete story, I guess some hidden intentions from manufacturers, politics and others.....

#4 by Eric Östlund on February 29, 2008 at 7:45 p.m.

The effect of what you have described is a real problem, which is not dealed with seriously. Last spring a large department store in Stockholm city decided to be Green and changed all spots and lamps to CFLs. The Zero in local three phase transformer station burned and shut down the electric supply in the area. Off cause the utillity company rushed out and doubled the zero line and all works well. It is not the first time it happens. The question if it really saves energy, well above pulses shows that but not as much as you might think.

Some say it a temporary problem as the LED lamps are comming  .. sooner than later, so I hope we do not make the same mistake with them in the era of the EUP directive.

 

#5 by Peter Van den Bossche on March 3, 2008 at 2:04 p.m.

The issue becomes worse indeed when one considers three-phase networks. I did a little test today:

Take three CFL of the type mentioned above and connect them in star. With this balanced load, one would expect the neutral current to be nearly zero of course.

Not so: the current in the neutral is 0,177 A, exceeding even the current in the phases (see above).

And the harmonics level of this current is just awful:  THD nearly 600 %!

 

Photo #6 by Tushar Mogre on March 17, 2008 at 3:05 p.m.

CFL lamps indeed gives distorted waveforms.

Still its an energy saving device.

In presence of harmonics Power as per IEC definition is 

                                             n=¥

Active Power (KW) =  S Vn . ILn . Cos (fn)

                                  n=1                                         where n is the harmonic number.

Now the bad effects of harmonics can be reduced considerably by usage of Harmonic Filters (tuned or active filters).

Better use the energy efficient CFL lamps that can save energy and then with appropriate filters to reduce the bad effect of harmonics. I think should be a better approach.

Photo #7 by Jameskutty Thomas on May 15, 2008 at 2:55 a.m.

In Comment No. 2 - The Power factor of CFL is mentioned as PF=0,633 leading.

Does CFL has a leading factor? I don't believe so. Might be clerical error.

Along with the Harmonic Distortion, low PF has a predominant role, in case of CFL. High Power Factor CFLs are there to comensate for. Also, less harmonic, being with harmonic filters.

Anyhow, CFLs are near to be replaced with OLEDs!

Photo #8 by Doug Powell on September 23, 2008 at 4:59 p.m.

This is very interesting.  is there anyone who has done experiment posted o'scope shots of the sinewave shape?

 

-Doug

#9 by Peter Van den Bossche on September 24, 2008 at 4:13 p.m.

There is an interesting IEEE article on this subject, including waveforms:

Study and Characterization of Waveforms From Low-Watt ($≪$25 W) Compact Fluorescent Lamps With Electronic Ballasts
Cunill-Sola, J.; Salichs, M.;
Power Delivery, IEEE Transactions on
Volume 22,  Issue 4,  Oct. 2007 Page(s):2305 - 2311 

#10 by Brown Erik on August 16, 2010 at 7:04 p.m.

I have always found the compact fluorescent lamps to be a fold better than the incandescent lamps. We can see that the power quality of the compact fluorescent lamps is something which can be seen just when we install it. I still, however, do not understand as to why people run after incandescent lamps. They are just becoming fools in my opinion, becoming fools because of the sly advertisements! Those pople who fall for advertisements are the ones who buy these lights.I have also seen that these lamps are good for the health of the eye as well. Hence less consulting the medical areas for eye problems!

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