Candlepower versus wattage

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ElectricianJeff

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Finally got to attend first hockey game of the season last night. Got there early and they had one of those trailer rigs going that shine four rotating lights into the night sky. It wasn't dark yet and I got to checking it out closer. It has a sticker on it that said 6 million candlepower. Did a little research this morning trying to find a way to convert candlepower to wattage without much luck. This all in one setup had a diesel 15 KW generator which seems like way overkill for what they had there. Anybody know about these setups that could share some "light" on what sort of load the are serving? I'm just being curious.
 
Efficiency of the lighting source will change candlepower in relation to watts.

You will have a lot more light per watt from an HID source than you will have from an incandescent source. But I bet you already knew this.

Do you know what type of light source is used for the lights in question?
 
I have a hand held spot light that's 15 million candle power.

It uses a 12 volt SLA battery (about the size as one would start a garden tractor with) as a power source.

Since CP is affected by the reflector and beam size, I don't think there is a direct correlation between watts and CP.

Here is one like it:

http://spyville.com/searchlight-spotlight.html

spyville_2245_77707163
 
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Were these carbon-arc lamps ? They were popular as search lights during WW II. Strike an arc between two carbon rods with

a mirrored surface behind the arc. Then the whole works might rotate in a circular motion. Very similar to arc welding.

I am sure the web has several examples & better descriptions.
 
John120/240 said:
Were these carbon-arc lamps ? They were popular as search lights during WW II. Strike an arc between two carbon rods with

a mirrored surface behind the arc. Then the whole works might rotate in a circular motion. Very similar to arc welding.

I am sure the web has several examples & better descriptions.
Click to expand...

I think more modern ones are xenon lamps, so are airport beacons, and motion picture projection lamps.
 
John120/240 said:
Were these carbon-arc lamps ? They were popular as search lights during WW II. Strike an arc between two carbon rods with

a mirrored surface behind the arc. Then the whole works might rotate in a circular motion. Very similar to arc welding.

I am sure the web has several examples & better descriptions.
Click to expand...
I haven't seen those in years. In my youth, I used to see them all the time at special events. Behemoths.
 
Lumen is to pound as is candela is to psi.


If you place a 1 lb weight on a 1" x 1" slab, the resulting pressure is 1 psi.
If you attach a smaller piece on bottom of the peg that is 1/10" x 1/10" it is 0.1 x 0.1 = 0.01in, and 1/0.01 = 100 psi.

Same idea.
 
ElectricianJeff said:
Finally got to attend first hockey game of the season last night. Got there early and they had one of those trailer rigs going that shine four rotating lights into the night sky. It wasn't dark yet and I got to checking it out closer. It has a sticker on it that said 6 million candlepower. Did a little research this morning trying to find a way to convert candlepower to wattage without much luck. This all in one setup had a diesel 15 KW generator which seems like way overkill for what they had there. Anybody know about these setups that could share some "light" on what sort of load the are serving? I'm just being curious.
Click to expand...

I haven't looked at them up-close, but they're probably MH or a high pressure short-arc xenon.

Short arc xenon produces a good point source and it is a wide spectrum lamp with sunlight like quality. It offers very easy manipulation using optics. Multi-kW short arc xenon are used for police/search & rescue helicopter spot lights and projection lamp in commercial theatres like IMAX.
 
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