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As we have switched to cfl's I was wondering how much they actually save

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Home » Discuss » Topic Forums » Environment/Energy

madokie

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Mon Jan-14-08 10:36 AM
Original message

As we have switched to cfl's I was wondering how much they actually save

so I got my p3 kill-a-watt meter out and plugged in a table lamp with a 60 watt incandescent lamp and then the equivalent cfl.

heres what I recorded, line voltage 118.7 volts

60 watt incandescent 60 watt equivalent light output Compact Florescent

.47 amp .19 amp
55 watts 14 watts
55 VA 22 VA
.99 power factor .60 power factor

for the same equivalent light I am paying for .22 kw for the cfl where as the incandescent it is .55 kw. My question is is this correct in what I presume it cost to operate these two light sources. TIA

We pay .08 cents a kwh

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bpeale

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Mon Jan-14-08 10:42 AM
Response to Original message

1. HELP! YOU'RE SQEEZING MY BRAIN! THIS IS TORTURE!

i can't think about things like this

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Ian David

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Mon Jan-14-08 10:45 AM
Response to Original message

2. It takes me three days to make a cake in my daughter's easy-bake oven with a CFL.

What a waste.

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wtmusic

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Mon Jan-14-08 12:21 PM
Response to Reply #2

8. LOL an inconvenient truth nt

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madinmaryland

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Mon Jan-14-08 10:45 AM
Response to Original message

3. Why the different power factors?

.055kw vs. .014kw.

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madokie

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Mon Jan-14-08 10:55 AM
Response to Reply #3

4. this would be better than me trying to explain

All I know is that the power factor is an important aspect as to the actual cost. dm

http://en.wikipedia.org/wiki/Power_factor

The power factor of an AC electric power system is defined as the ratio of the real power to the apparent power, and is a number between 0 and 1 (frequently expressed as a percentage, e.g. .5 pf = 50% pf). Real power is the capacity of the circuit for performing work in a particular time. Apparent power is the product of the current and voltage of the circuit. Due to energy stored in the load and returned to the source, or due to a non-linear load that distorts the wave shape of the current drawn from the source, the apparent power can be greater than the real power. Low-power-factor loads increase losses in a power distribution system and result in increased energy costs.

Power factor in linear circuit

Instantaneous and average power calculated from AC voltage and current with a unity power factor (φ=0, cosφ=1)
Instantaneous and average power calculated from AC voltage and current with a zero power factor (φ=90, cosφ=0)
Instantaneous and average power calculated from AC voltage and current with a lagging power factor (φ=45, cosφ=0.71)In a purely resistive AC circuit, voltage and current waveforms are in step (or in phase), changing polarity at the same instant in each cycle. Where reactive loads are present, such as with capacitors or inductors, energy storage in the loads result in a time difference between the current and voltage waveforms. This stored energy returns to the source and is not available to do work at the load. A circuit with a low power factor will have thus higher currents to transfer a given quantity of real power than a circuit with a high power factor.

Circuits containing purely resistive heating elements (filament lamps, strip heaters, cooking stoves, etc.) have a power factor of 1.0. Circuits containing inductive or capacitive elements (lamp ballasts, motors, etc.) often have a power factor below 1.0. For example, in electric lighting circuits, normal power factor ballasts (NPF) typically have a value of (0.4) - (0.6). Ballasts with a power factor greater than (0.9) are considered high power factor ballasts (HPF).

The significance of power factor lies in the fact that utility companies supply customers with volt-amperes, but bill them for watts. Power factors below 1.0 require a utility to generate more than the minimum volt-amperes necessary to supply the real power (watts). This increases generation and transmission costs. For example, if the load power factor were as low as 0.7, the apparent power would be 1.4 times the real power used by the load. Line current in the circuit would also be 1.4 times the current required at 1.0 power factor, so the losses in the circuit would be doubled (since they are proportional to the square of the current). Alternatively all components of the system such as generators, conductors, transformers, and switchgear would be increased in size (and cost) to carry the extra current.

Good power factor is considered to be greater than 90 to 95%. Utilities typically charge additional costs to customers who have a power factor below some limit, which is typically 90 to 95%. Engineers are often interested in the power factor of a load as one of the factors that affect the efficiency of power transmission.

Definition and calculation

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bananas

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Mon Jan-14-08 11:26 AM
Response to Original message

5. You get charged for watts, not VA

so for the same equivalent light you pay .14 kw for the cfl where the incandescent is .55kw.
Watts is the actual power used, VA is just average voltage times average amps.
power factor = watts / VA

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madokie

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Mon Jan-14-08 12:16 PM
Response to Reply #5

7. during the '90 I worked for my brothers company and we installed a hugh capacitor bank

to correct the power factor in the plant where we worked. It was an iron foundry btw and by correcting the power factor it saved them a tremendous amount on their electric bill per month, it was in the six figures. The power factor, if I remember correctly as it was explained to me then, is the difference between the amount we pay and the actual amount we use. I had the power factor checked here when we first bought this place and the pf of the line supplying power to us was at .93%. There is six houses on this transformer supplying our power.

http://en.wikipedia.org/wiki/Power_factor

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hunter

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Mon Jan-14-08 02:12 PM
Response to Reply #7

11. Modern foundries are using switching power supplies.

It's the Godzilla version of the switching power supply in a personal computer. This reduces the need for large capacitor banks, which tend to introduce other sorts of efficiency and operational problems upstream.

A foundry can be very hard on on a power network. In a plant that doesn't have a sophisticated switching power supply system very large capacitors are used against the inductance of the system to form an electrical flywheel that shaves off the sharper edges of the foundry's electrical demand.

Before these switching power supplies existed electric foundries couldn't represent more than a small fraction of a power network's demand.

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madokie

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Mon Jan-14-08 02:30 PM
Response to Reply #11

12. the power company, GRDA in this case, designate the minutes each hour they can use the melting

Edited on Mon Jan-14-08 02:36 PM by madokie

furnaces, the foundry makes a request and the power company actually turns the furnaces on from their control center, ie either allowing it or not I think is how it works. its a pretty simple so far proven system they have worked out amongst themselves. These are induction furnaces I'm talking about here too.

splchk

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FREEWILL56

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Mon Jan-14-08 02:55 PM
Response to Reply #5

14. So as not to confuse anybody here I must correct you that the kilowatts

Edited on Mon Jan-14-08 03:05 PM by FREEWILL56

are .014kw and .055kw. I am billed for kilowatt hours and not the power factor, but I believe some businesses they do penalize if they have a bad PF by raising the cost for each kwh used. This could be different for different electric companies though.
edit to add:
I have a Kill-a-watt meter too and love it.

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OKIsItJustMe

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Mon Jan-14-08 11:41 AM
Response to Original message

6. About Power Factor and CFL's

Edited on Mon Jan-14-08 11:56 AM by OKIsItJustMe

http://www.energyideas.org/default.cfm?o=h,g,ds&c=z,z,2012

...

Ballasts transform the line voltage to one usable by the fluorescent lamp, and usually come in two power factors. Power factor has to do with the efficiency with which this voltage transformation is performed. A high power factor (HPF) lamp carries a premium price at retail level, but in large quantities from a manufacturer, the price difference may be only pennies. A HPF is most desirable, particularly if your utility charges you for power factor (and if they don't already, that may change in today's energy climate). Normal power factor (NPF) lamps are commonly found in home improvement centers and are rated at .50. Normal power factor means the utility has to deliver more power than your meter will charge you for and, in effect, penalizes the utility. You may experience some delays in obtaining HPF lamps, but I encourage the patience required to obtain high quality products. Ask your utility about any incentives they may offer for lighting system retrofits.

...

To make things simple, I'd suggest looking for Energy Star rated CFL's:
http://www.energystar.gov/index.cfm?c=cfls.pr_cfls

Note however that the Energy Star rating only requires the power factor to be > 0.50, so your bulb apparently would qualify.
http://www.energystar.gov/ia/partners/product_specs/program_reqs/cfls_prog_req.pdf

http://irc.nrc-cnrc.gc.ca/pubs/cp/lig3_e.html

...

The power the utility delivers is called apparent power. It is the vector sum of two components: active power (which does all the work in electrical devices) and reactive power (which does no work). The ratio of active power to apparent power is called the power factor. Incandescent lamps have a power factor of unity (1.0), while CF systems have power factors ranging from 0.3 to near unity. Power factors below 0.6 are generally considered poor, while values above 0.9 are very good.

Residential utility meters measure only active power, so utility companies can't charge home-owners for reactive power, even though it costs them money to transport it over transmission lines. Some larger utility customers are charged for apparent power. Apparent power increases as power factor decreases, so larger utility customers might prefer CF systems that include a power factor correction circuit.

...

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madokie

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Mon Jan-14-08 12:26 PM
Response to Reply #6

9. thanks for making a muddy stream a little bit clearer for me

as I stated in my last reply I worked where we installed the equipment that corrected the pf of a large plant and it saved them bunches of bucks, not so much percentage wise I think but a sizable chunk of cash nevertheless. So this was more than likely initialized by the power company for their benefit and the cost saving for the foundry was a side effect is what I'm a thinking now, hmmmm

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ConcernedCanuk

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Mon Jan-14-08 01:55 PM
Response to Original message

10. One of the reasons I switched to CFLs is because I use solar/battery backup

.
.
.

Can't give you any scientific/numerical backup

But my battery/solar pack lasts 4-5 times longer using CFLs

ANOTHER thing I like about CFLs is that they run much cooler than incandescents

So I can run higher "wattage"(lumens, actually) in ceiling fixtures and portable lamps without the concern of fire or burning my skin on touch

My Canuk 2 cents worth . . .

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madokie

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Mon Jan-14-08 02:35 PM
Response to Reply #10

13. I've wonder about that, using a higher lumen cfl's

with our fixtures but so far I haven't needed too but its good to know I can if need be.

we have shaved about 25 bucks from our monthly electric bill primarily by switching to cfl's, in fact the savings has already paid us back for the cost of the bulbs themselves in a matter of only a few months time.

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