jgd@rsiatl.UUCP (John G. De Armond) (04/06/90)
jlg@lambda.UUCP (Jim Giles) writes: >In article <1990Apr4.174234.24288@tc.fluke.COM> inc@tc.fluke.COM (Gary Benson) writes: >> >> It costs more to turn lights off and on than to leave them turned on >> (regardless of the ratio of on to off time). >This is true for florescent lights. It requires an average of several >minutes worth of electricity to 'power-up' a florescent light. So, if >you're not planning to leave it off for a larger time that that, leave >it on. Incandescent bulbs should be turned off when they're not in use >no matter how short the interval till the are needed next. Actually no. This issue came up a few months ago and when the disucssion reached mythalogical proportions, I decided to make some measurements using a laboratory precision watt-hour meter. I measured the total power consumed from the instant of power application to the instant the bulb reaches full intensity and calculated a smoothed rate. I then compared that rate to the steady state consumption rate. I measured what was available in my lab which included a 20 watt old-style starter lamp, a dual tube 40 watt shop lite and a dual tube 100 watt industrial fixture. The latter 2 are both cold cathode, "instant on" types. The 100 watt lamp contains a "high power factor" ballast. For the instant-on lamps, the power consumption is actually lower than in steady-state. It is true that the lamp draws more AMPS but this is wattless current due to the low power factor of the unloaded ballast. The old-style starter lamp drew marginally (~15%) more power starting than during steady-state. Nontheless, the TOTAL power consumed during starting is equal to about 5 to 10 seconds of steady-state operation. The above isNOT to say that leaving lights on does not have merit. With flourosenct as well as filament lamps, the major consumption of internal resources occurs during powerup. In the case of filament lamps, a FAR greater factor in life is the applied voltage. A few volts higher than rating will completely swamp any variations due to duty cycle. John -- John De Armond, WD4OQC | We can no more blame our loss of freedom on congress- Radiation Systems, Inc. | men than we can prostitution on pimps. Both simply Atlanta, Ga | provide broker services for their customers. emory!rsiatl!jgd | - Dr. W Williams | **I am the NRA**
rick@ofa123.FIDONET.ORG (Rick Ellis) (04/12/90)
In a message of <Apr 05 23:29>, Jim Giles (jlg@lambda.UUCP ) writes:
JG> This is true for florescent lights. It requires an average of several
JG> minutes worth of electricity to 'power-up' a florescent light. So, if
JG> you're not planning to leave it off for a larger time that that, leave
JG> it on. Incandescent bulbs should be turned off when they're not in
JG> use no matter how short the interval till the are needed next.
Try 15 seconds.
--
Rick Ellis
...!{dhw68k,zardoz,lawnet,conexch}!ofa123!rick rick@ofa123.FIDONET.ORG
714 544-0934 2400/1200/300rwb@vi.ri.cmu.edu (Bob Berger) (04/12/90)
In article <1646@rsiatl.UUCP>, jgd@rsiatl.UUCP (John G. De Armond) writes: > It is true that the lamp draws more AMPS but this is > wattless current due to the low power factor of the unloaded ballast. Don't dismiss this "wattless" power so quickly. It is exactly what you are charged for by the utilities meter. Although you may feel better because you are not using "real" power, I'm more concerned with the bill they send me. The rate at which the meter turns is proportional to the volt-amperes of apparent power.
roy@phri.nyu.edu (Roy Smith) (04/13/90)
In article <8830@pt.cs.cmu.edu> rwb@vi.ri.cmu.edu (Bob Berger) writes: > Don't dismiss this "wattless" power so quickly. It is exactly what you > are charged for by the utilities meter [...] The rate at which the meter > turns is proportional to the volt-amperes of apparent power. Sorry, but this is just plain wrong. Watt-hour meters read actual true power, V*I*cos(theta). The "wattless" power, known in the vernacular as VARS (Volt-Amps Reactive) does not register on the meter. If you are an industrial user, the power company may monitor your power factor (the cos(theta) mentioned above, where theta is the phase angle between the voltage and current vectors) and get on your case (i.e. charge you extra) if it gets too low, but the Watt-hour meter *still* reads true power. VARS are bad because while they don't constitute any real power that you are consuming (and thus being charged for), they do increase the current draw, and lead to larger resistive losses in the power distribution grid. In the ultimate nightmare scenario, it may even cause the generators to loose sync, at which point you are only happy if you own stock in candle and flashlight battery companies. -- Roy Smith, Public Health Research Institute 455 First Avenue, New York, NY 10016 roy@alanine.phri.nyu.edu -OR- {att,cmcl2,rutgers,hombre}!phri!roy "Don't Worry, Be Happy"
rsd@sei.cmu.edu (Richard S D'Ippolito) (04/13/90)
Subject: Re: Urban Myths again. -- Indeed! Let's squelch this one. In article <8830@pt.cs.cmu.edu> Bob Berger writes: >Don't dismiss this "wattless" power so quickly. It is exactly >what you are charged for by the utilities meter. Although you >may feel better because you are not using "real" power, I'm more >concerned with the bill they send me. The rate at which the meter >turns is proportional to the volt-amperes of apparent power. Sorry, the meter measures real energy, i.e., Watt-Hours, and not VA-hours, which I have never seen measured. Meters which measure VA are labeled volt-ampere (or apparent power) meters and have scales calibrated in VA or KVA. Meters which measure power are called wattmeters and have scales calibrated in Watts or KW. The meter on your house is calibrated in KWHr, and is displays the time integral of real power (Watts) consumption, in other words, energy, which is what the utility sells. Unless you are a large commercial or industrial establishment, you don't get penalized for non-unity power factor. Rich -- How do you know how I can see lessen you kin look out my eyes? Hoke, in _Driving Miss Daisy_ rsd@sei.cmu.edu ------------------------------------------------------------------------
brian@ucsd.Edu (Brian Kantor) (04/13/90)
One place I worked used so much electrical power that the power company ran a direct feed from the substation to the plant, and we had both watt AND var metering on the various distribution points. How much power? Well, they moved the plant to Washington state to get their power direct from a dam instead of buying it from SDG&E. When you consider that the product was costed at about $1,000 of raw material and $5,000 of electricity each, you know it's a lot of power. We're talking 3-inch cylinders of pure ruby or sapphire, about 15 inches long, BTW. - Brian
bph@buengc.BU.EDU (Blair P. Houghton) (04/14/90)
In article <13085@ucsd.Edu> brian@ucsd.edu (Brian Kantor) writes: >consider that the product was costed at about $1,000 of raw material and >$5,000 of electricity each, you know it's a lot of power. > >We're talking 3-inch cylinders of pure ruby or sapphire, about 15 >inches long, BTW. Um, excuse me, but I'll buy the $5k in energy cost, but there isn't any way you're going to convince me that the "raw materials" for 106 cubic inches of solid ruby or sapphire are going to cost $1000. I'd still be leery if you said $1000000, but it's a little closer to the ballpark. Perhaps you included the materials for the processing, but not the actual minerals, eh? --Blair "And if you didn't, where did you say this place was?"
forbes@aries.scs.uiuc.edu (Jeff Forbes) (04/14/90)
In article <5663@buengc.BU.EDU> bph@buengc.bu.edu (Blair P. Houghton) writes: >In article <13085@ucsd.Edu> brian@ucsd.edu (Brian Kantor) writes: >>consider that the product was costed at about $1,000 of raw material and >>$5,000 of electricity each, you know it's a lot of power. >> >>We're talking 3-inch cylinders of pure ruby or sapphire, about 15 >>inches long, BTW. > >Um, excuse me, but I'll buy the $5k in energy cost, but >there isn't any way you're going to convince me that the >"raw materials" for 106 cubic inches of solid ruby or >sapphire are going to cost $1000. I'd still be leery if >you said $1000000, but it's a little closer to the >ballpark. > >Perhaps you included the materials for the processing, but not >the actual minerals, eh? A 15" long 3" diameter sapphire rod is about 7 kilograms of alpha-aluminum oxide. 99.9+% aluminum oxide from Aesar is about $73.00 a kilo or $511.00 dollars for the raw materials. If you want to make ruby add another $100.00 or less for ultrapure chromium oxide. Now melt it in an electric furnace and slowly pull out a seed crystal, and then you have spent $5000.00 on electricity and you have a very large sapphire rod. Jeff