MikeyinLA
Member
Really? , really?
Do you believe that frequent on/off substantially shortens fluorescent light life?
- Thread starter Electric-Light
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Really? , really?
gar
Senior Member
- Location
- Ann Arbor, Michigan
- Occupation
- EE
110506-2051 EDT
The results of this poll really surprise me.
Suppose it really took a lot of power to initiate the arc in the tube. For example 1,000,000 watts for 1 microsecond. Thus the turn on energy would be 1 watt-second. Next make the on-off duty cycle 10 minutes on and 10 minutes off and assume a single 40 W bulb. In that 20 minute period the tube will consume 40*10*60 = 24,000 watt-seconds of energy, or 6.67 watt-hours, or 0.006,67 KWH. Over a 1 hour period the consumption is 3*6.67 = 20 W-hours, or 0.020 KWH. A different way to get the same answer is --- the average power is 20 W because the duty cycle is 50%. So during an hour period the consumption is 0.020 KWH.
What is 3 times 1 watt-second? It is 3 watt-seconds. How much is this in KWH? It is 3/3600 KWH, or 0.000,83 KWH. This is totally insignificant in comparison to the energy to run the tube.
I picked a totally ridiculous power level just to make a point. Power is not the issue. Energy is.
I do not have any data on the power level to start a fluorescent tube, but it is not much different than the operating power and is only present for at most a few cycles. Basically a magnetic ballast is a current limiting device and to initiate the arc the current won't be much different than the operating current. Also in all probability for a cold cathode tube the arc strikes within 1/2 to 1 cycle, 16 milliseconds.
If you start an incandescent bulb from room temperature at the peak of the voltage waveform and in a relative sense compare this to a fluorescent tube, then I expect that the incandescent consumes more energy for start up than the fluorescent.
.
The results of this poll really surprise me.
Suppose it really took a lot of power to initiate the arc in the tube. For example 1,000,000 watts for 1 microsecond. Thus the turn on energy would be 1 watt-second. Next make the on-off duty cycle 10 minutes on and 10 minutes off and assume a single 40 W bulb. In that 20 minute period the tube will consume 40*10*60 = 24,000 watt-seconds of energy, or 6.67 watt-hours, or 0.006,67 KWH. Over a 1 hour period the consumption is 3*6.67 = 20 W-hours, or 0.020 KWH. A different way to get the same answer is --- the average power is 20 W because the duty cycle is 50%. So during an hour period the consumption is 0.020 KWH.
What is 3 times 1 watt-second? It is 3 watt-seconds. How much is this in KWH? It is 3/3600 KWH, or 0.000,83 KWH. This is totally insignificant in comparison to the energy to run the tube.
I picked a totally ridiculous power level just to make a point. Power is not the issue. Energy is.
I do not have any data on the power level to start a fluorescent tube, but it is not much different than the operating power and is only present for at most a few cycles. Basically a magnetic ballast is a current limiting device and to initiate the arc the current won't be much different than the operating current. Also in all probability for a cold cathode tube the arc strikes within 1/2 to 1 cycle, 16 milliseconds.
If you start an incandescent bulb from room temperature at the peak of the voltage waveform and in a relative sense compare this to a fluorescent tube, then I expect that the incandescent consumes more energy for start up than the fluorescent.
.
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Electric-Light
Senior Member
Where do you get that idea? I'm asking for the sake of asking just to see what people who frequent this forum think. This poll result is of no use for marketing anyways.
I felt like asking, because every once in a while, I come across people who say "it saves money if you don't turn it off that often because fluorescent bulbs work hard and use more power(what they mean is "energy") to turn it on."
Some of you may recall my poll.. What is the power of incandescent lamp at 200v 5A. It was just for fun.
http://forums.mikeholt.com/showthre...the-power-of-an-incandescent-lamp-at-200v-5A?
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