I saw this thread over at JLC.
http://forums.jlconline.com/forums/showthread.php?t=43395
Lutron has out a “green” or “eco” dimmer.
“SkyLark 600W Incandescent slider with preset, S-600P- “Normal Energy Savings”
SkyLark 600W Incandescent slider with preset, S-600PE- “15% energy savings”
Is this a Green Dimmer? Lutron calls this switch Eco-Dim.”
All it is is a stop that keep you from setting the dimmer to full brightness.
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A-holes. Hey every group has to have one. And I have been elected to be the one. I should make that my tagline.
Edited 7/6/2008 10:24 am by BillHartmann
Replies
C'mon. You know if it sells, it's simply time to jump on the bandwagon.
PAHS works. Bury it.
I was always under the impression that a dimmer ... will decrease the watts/energy to the lamp ... but will generate all the rest of the watts in the rheostat dimmer device ... leaving us w/ really no savings ... where is an electrician who understands this stuff that can set us straight?
good questionhard tellin, not knowinMike Smith Rhode Island : Design / Build / Repair / Restore
Rheostats have not been used since the 20's or 30's for light dimming etc possibly in theaters.Since the 60's all residential and light commercial dimmers have been solid state devices.Most commonly a TRIAC is used for the electronic switch. Those are "off" until they are triggered ("fired"). Then they say on unitl current drops to zero when the AC voltage drops to zero.The length of time between when the switch off to when they are fired for the next cycle determines the "average" (actually RMS or root mean squared)voltage that the bulb sees and how bright the light is.http://home.howstuffworks.com/dimmer-switch2.htm
http://www.epanorama.net/documents/lights/lightdimmer.htmlThe triac has a voltage drop of about 1.3-1.5 volts. So whenever any current is flowing through it there is a small voltage drop and thus heat loss. For a dimmer at "full on" driving 300 watts of bulbs then the losses would be 3 3/4 watts. That is what makes a dimmer warm.When the lights are dimmed the current is reduced and the power losted in the dimmer is even less.Note that some, but very few, dimmers have bypass feature. When turned fully on there is a mechanical contact that bypasses the circuitry so that there are no losses in the dimmer. I know some of the Pass and Seymour dimmers have that feature." but will generate all the rest of the watts in the rheostat dimmer device ... leaving us w/ really no savings ."While rheostat's do dumps tons of heat. Depending on the load and how much the lights are dimmed you might be talking about 30-60 watts for a 300 load. P = V*I
V = I*R
P= V(squared)/RWhen you dim you are are increasing the resistance of the rheostat so that the total resistance of the circuit is increased and the total power from the circuit is less.BTW a couple of weeks ago I was in a house built in the 20's. It had a dimmer for the dinning room light. It was box about 5" square, with a 2" dia knob on it. I suspect that it was some kind of adjustable transformer.But it could have been a rheostat and there would have been enough room in the walls for their to be a chase for cooling air..
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A-holes. Hey every group has to have one. And I have been elected to be the one. I should make that my tagline.
Where do people go the idea tht rheostats are used for dimming lights.Has anyone every seen one.http://www.surplussales.com/potentiometers/rheostats/PotsRheost-2.html"(RWA) 0448
Rheostat, 25 ohm, 2 amps, 50 watt, 1/4" shaft, 3" diameter. Bushing mount. Made by Ohmite."That would be OK based on the wattage, but the current rating would be too low for 300 watt of load."(RWA) M22/11-0111
Rheostat, 35 ohm, 2.93 amp, 300 watt, 3/8" shaft. 6" diameter."That would work.PS I also went back and corrected the URL in the first post..
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A-holes. Hey every group has to have one. And I have been elected to be the one. I should make that my tagline.
Edited 7/6/2008 10:32 am by BillHartmann
I knew I could depend on some of you electro geeks to 'splain it to us. Thanks much ... makes sense, I guess. Similar to electronic ballasts, I'm thinking.
Instead of diverting energy from the light bulb into a resistor, modern resistors rapidly shut the light circuit off and on to reduce the total amount of energy flowing through the circuit. The light bulb circuit is switched off many times every second.
Most of these are built around the same simple idea -- chopping up AC current to reduce the total energy powering a light bulb. At the most basic level, that's all there is to it.