Is CFL an inductive load?

  • #1
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As far as I know, Compact Fluorescent Lamp (CFL) is an inductive load.
I understand that inductive load doesn't allow an immediate change in current. When the circuit was initially open (through open switch) then became close, the inductive load was energized. So opening again the circuit after a long period of time makes the inductive load to have enough energy to maintain its magnetic field, so voltage as well (I know it was called back emf).
I am afraid that our CFL at our bathroom will eventually find its time to break ( or unfortunately to blast and cause fire). Since it's a bathroom,the CFL is being switch on and off frequently. How do I manage to create a switch or circuit to avoid that back emf (or even reduce) which causes the low lifespan of our CFL thus preventing cause of fire (As my conclusion). I have seen in the internet about putting a flyback diode helps to prevent back emf but it is new to me so I need guidance.

So my query here is: I really don't know how to make a circuit for better switching of our CFL to prevent or reduce back emf , improve even a little bit the life span of the CFL and to avoid danger and fire. Please kindly help me. you can propose a circuit or help me to make one.

This is our CFL having 18 W, 220 VAC, 60 Hz:
DSC00276.JPG


Kindly help me to solve this problem to prevent any danger in our house.
By the way this can't be replace because it was preferred by our family members (yeah all of them).
 

Answers and Replies

  • #2
dlgoff
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I don't think there's enough induction to worry about as it uses a "switching power supply" (ballast) that's in the CFLs base.

Electronic ballasts contain a small circuit board with rectifiers, a filter capacitor and usually two switching transistors. The incoming AC current is first rectified to DC, then converted to high frequency AC by the transistors, connected as a resonant series DC to AC inverter. The resulting high frequency is applied to the lamp tube.
Elektronstarterp.jpg


http://en.wikipedia.org/wiki/Compact_fluorescent_lamp
 
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  • #3
Doug Huffman
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Your short CFL service life may be due to their need of an elevated operating temperature for efficiency (read low current).

Like my 12 y.o. 50 mpg diesel VW, I will not change while I can afford to buy replacement car parts or incandescent lamps. Incandescent lamp heat is not an inefficiency in an electrically heated home at N45° and 0°F ambient.
 
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  • #4
Averagesupernova
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Your short CFL service life may be due to their need of an elevated operating temperature for efficiency (read low current).

Like my 12 y.o. 50 mpg diesel VW, I will not change while I can afford to buy replacement car parts or incandescent lamps. Incandescent lamp heat is not an inefficiency in an electrically heated home at N45° and 0°F ambient.
OMG finally someone who actually 'gets it'. I pointed this out to someone at a home show from an electrical cooperative who was demonstrating the efficiency of CFLs. They did not like to hear what I had to say.
 
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  • #5
Doug Huffman
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LOL My standby lamp is a diesel powered Welsbach mantle lamp by Aladdin. It is specified at 60 We equivalent light that is white, odorless and with abundant heat. I've never had to run it long enough to estimate fuel consumption for actual heat output.

ETA More: House heat is primarily to keep pipes from freezing and plastics from cracking. We practice micro-heating with electric lap robes, mattress pad, shoulder wrap. My downstairs easy chair snuggles up to the main (read, only interior wall) electric baseboard.

When my house was built, we, my Island, produced all our electric power with big DE generators. To ensure sufficient load at night, electric heating was encouraged with subsidized heating power. I have two electric power meters, one for heat and one for utility power - lights and such.
 
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  • #6
jim hardy
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Where i live CFL's are a capacitive load not an inductive one. Switching one on draws a big gulp of current.
In one room of my house it causes the touch-dimmer equipped incandescent lamps to turn off. So does switching on the computer. I think the neutral for that room's outlets is routed improperly creating a loop antenna.

If you are experiencing short life on your CFLs,
the main culprit is heat. Are they in a fixture that points down, trapping heat around the base ? Use a fixture that points up, or is ventilated.

Dont even think about using a dimmer on ordinary CFL's. It'll overheat the inrush limiter , there are reports of pyrotechnic results.

I'm with Doug - i bought a lifetime supply of 100 watt incandescents and touch dimmer modules.
 
  • #7
NascentOxygen
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The best way to extend the life of a CFL is to replace it with a LED globe. :)

LEDs can cope with many on/off cycles. LED globes seem to have a poor power factor, but it's a low reactive power. Often a manufacturer offers the globe in two versions: dimmable and non-dimmable. The latter show slightly more lumens for a given power.
 
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  • #9
meBigGuy
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This is off-topic, but I wonder if there are places in the US where electricity is cheaper than gas (near hydro projects, for example) to heat your house, so CFL actually causes the heating bill to go up?
 
  • #10
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As far as I know, Compact Fluorescent Lamp (CFL) is an inductive load.
I understand that inductive load doesn't allow an immediate change in current. When the circuit was initially open (through open switch) then became close, the inductive load was energized. So opening again the circuit after a long period of time makes the inductive load to have enough energy to maintain its magnetic field, so voltage as well (I know it was called back emf).
I am afraid that our CFL at our bathroom will eventually find its time to break ( or unfortunately to blast and cause fire). Since it's a bathroom,the CFL is being switch on and off frequently. How do I manage to create a switch or circuit to avoid that back emf (or even reduce) which causes the low lifespan of our CFL thus preventing cause of fire (As my conclusion). I have seen in the internet about putting a flyback diode helps to prevent back emf but it is new to me so I need guidance.

So my query here is: I really don't know how to make a circuit for better switching of our CFL to prevent or reduce back emf , improve even a little bit the life span of the CFL and to avoid danger and fire. Please kindly help me. you can propose a circuit or help me to make one.

This is our CFL having 18 W, 220 VAC, 60 Hz:View attachment 77502

Kindly help me to solve this problem to prevent any danger in our house.
By the way this can't be replace because it was preferred by our family members (yeah all of them).
Modern CFLs are electronically ballasted. Current they draw is typically heavily distorted. Displacement power factor is leading which means they present more capacitive than inductive load to the feeding network. Knowing their harmonics contaminate the network, that they are not as "green" as advertised, and die on average in service earlier than claimed by manufacturers, I don't like them at all. I don't have a single CFL bulb installed in my house.
 
  • #11
jim hardy
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Knowing their harmonics contaminate the network, that they are not as "green" as advertised, and die on average in service earlier than claimed by manufacturers, I don't like them at all. I don't have a single CFL bulb installed in my house.
from that Wikipedia link by Doug,
220px-CFL_Positive_power.png

Voltage and current for a 120 V 60 Hz 30-watt compact fluorescent lamp.

I have a few of them.
One in kitchen fixture that stays on constantly. First one lasted seven years, second one a few months, third one four years and we're two years into third er, make that fourth one.
A couple others in fixtures that are hard to reach.
All my table lamps are incandescent with dimmers.

They are nice for in-the-ceiling fixtures that aren't well ventilated, because they make so much less heat therefore aren't so hard on the PVC insulation on house wiring.

I dislike their unnecessary expensive complexity, and the mercury in landfills.
 
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  • #12
russ_watters
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This is off-topic, but I wonder if there are places in the US where electricity is cheaper than gas (near hydro projects, for example) to heat your house, so CFL actually causes the heating bill to go up?
Probably not: with an interconnected grid, consumers don't buy power from one power plant, they buy it regionally, at retail prices.

Now, when the alternative is propane, it can start to get close.
 
  • #13
Doug Huffman
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I dislike their unnecessary expensive complexity, and the mercury in landfills.
Last I saw, and it has been a while, the regulatory requirements for cleaning an Hg spill as from a broken florescent bulb/tube are not trivial.

Propane is my alternate heat source and primary cooking heat source, a 500 USgal tank that I have never significantly depleted. I order it topped off when I can guess the cost the lowest, this past refill at <US$2.60/USgal. During the crunch last winter, my provider did not exceed US$5.00.USgal propane and freely extended credit to those caught short.

1000KWH heat costs US$110 by the rate sheet that I just looked at, the meter-base charge is $7.00. My winter electric bill runs about $500/mo roughly evenly divided between heat and utility.
 
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The linked wiki article is quite misleading/wrong about some aspects of use of CFLs. For instance:
The use of CFLs in homes has no appreciable effect on power quality, but significant quantities of them in a large facility can have an impact. The power factor of CFLs does not significantly affect their energy-saving benefits for individual consumers, but their use in large numbers—such as in commercial applications or across millions of homes in a distribution system—could require infrastructure upgrades. In such cases, CFLs with low (below 30 percent) total harmonic distortion (THD) and power factors greater than 0.9 should be selected.
This claim doesn't hold for LV and distribution parts of the network. Massive use of CFLs in domestic installations has noticable effect on power quality there. This is more expressed in LV network parts located far from HV grid and at peripheries of EES. Average Joe doesn't care about harmonics junk his electronic devices and CFLs put back in the network, won't buy more expensive CFLs with low THD. He doesn't care about possibility of installation of electrical filter(s) too.
 
  • #15
Averagesupernova
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  • #16
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So are you all telling me that I should not mind the effect of switching (frequently) of CFL on our comfort room because switching frequently has no significant effect to CFL (which is an inductive load)? Is that what you want to tell me?
 
  • #17
jim hardy
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So are you all telling me that I should not mind the effect of switching (frequently) of CFL on our comfort room because switching frequently has no significant effect to CFL (which is an inductive load)? Is that what you want to tell me?
well, it's a capacitive not an inductive load.
In practice, switching it ON does apply a harsh transient called "inrush" to the electronic components.
If it's well designed and built it should withstand that transient repeatedly with no significant effect. That's a function of who built it. You get what you pay for.
Switching it OFF is by contrast a gentle transition.
 
  • #19
anorlunda
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This is off-topic, but I wonder if there are places in the US where electricity is cheaper than gas (near hydro projects, for example) to heat your house, so CFL actually causes the heating bill to go up?
22 municipalities in New York State were grandfathered by law to buy Niagara Falls power at 2 cents/kwH, while others in the same state paid as much as 29 cents/kwH. Politics need not be rational, nor fair.

My info is 10 years old. I don't know if things have changed since then.
 
  • #20
jim hardy
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Niagara Falls is an interesting area.
Here's a history of the power project.
http://www.niagarafrontier.com/power.html#Nfpower

As recently as 1970's industries around the Falls could buy power for 0.2 cent per kwh.
There were no transmission costs to be covered so everybody thought it fair enough.
When other parts of the state cried "foul" NYPA took over and levelled rates.
That made much of the local industry no longer economically viable.
Carborundum for example moved its factory from Niagara Falls to Brazil.

So, what's "fair" ?
 
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  • #21
mheslep
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This is off-topic, but I wonder if there are places in the US where electricity is cheaper than gas (near hydro projects, for example) to heat your house, so CFL actually causes the heating bill to go up?
Probably not: with an interconnected grid, consumers don't buy power from one power plant, they buy it regionally, at retail prices.

Now, when the alternative is propane, it can start to get close.
Russ - are you comparing gas heat to electric IR heating, or to electric heat pumps?

Edit: I see AverageSupernova answered earlier with:
http://www.efficiencymaine.com/at-home/home-energy-savings-program/heating-cost-comparison/
 
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  • #22
Averagesupernova
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I plugged in $.0586 per KWH into the link I provided for the baseboard electric heat. This is the sub-metered rate for electricity on heating and cooling systems in my area. I then dialed the other numbers around and came up with the following:
Propane energy star furnace needs to have propane drop to $1.04 a gallon to compete with electricity.
Natural gas energy star furnace needs to have natural gas drop to $1.16 to compete with electricity.
Oil fired energy star furnace needs to have fuel oil drop to $1.41 to compete with electricity.
-
This is figuring resistance heat. Using geothermal and air to air heat pumps I came up with the following:
To compete with fossil fuels at the above prices (which are severely cheaper than what people are paying now) a geothermal heat pump could have electricity go up to around $.19 and still compete. The air to air heat pump could have electricity go to about $.17 and still compete.
-
My parents house is heated with fuel oil. They paid $2.25 per gallon on their last fill. Going by the chart electricity can go to $.093 with resistance heating, which is what incandescents are, and be competitive with oil at $2.25 a gallon. So if your main electric rate is less than 9 cents compact florescent and LED bulbs are losing you money in the winter at fossil fuel prices that fall in line with $2.25 a gallon oil.
-
Edit: Actually the parents have a dual fuel setup. They have an air to air heat pump with backup being fuel oil. And their electric rate is $.0586 per kwh on heating and cooling.
 
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  • #23
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Here's an article written by somebody who dislikes CFL lamps as much as i do.
http://www.rense.com/general96/214law.html
I had joined "dislikers club" even before production of incadescent bulbs was banned. To certain extent I tolerate FL with HPF designed magnetic ballasts, but I never liked CFLs.
Niagara Falls is an interesting area.
Here's a history of the power project.
http://www.niagarafrontier.com/power.html#Nfpower
First Niagara Falls generators were 2 phase, 25 Hz machines. And such was power transmission too. It was much later when 3 phase generation/transmission of electrical power was adopted. Interestingly enough, frequencies like 25 Hz or 16.67 Hz can be found even today in some countries (used mostly to power railways)
 
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