power of a cold cathode bulb

[artis sideley]

Hi all,

What is the efficency of a cold cathod tubular bulb ? Is a 8W CCFL worth
the light output of a 80W plain old incandescent bulb ?

 

[JohnR66]

Hi all,

What is the efficency of a cold cathod tubular bulb ? Is a 8W CCFL worth
the light output of a 80W plain old incandescent bulb ?

Not nearly enough information to answer your question.
If your CCFL is similar in efficiency as the typical CFL, expect them to be
3 to 5 times more efficient than the typical incandescent lamp runing in the
15 lumens/w range.
John

 

[Don Klipstein]

Not nearly enough information to answer your question.
If your CCFL is similar in efficiency as the typical CFL, expect them to be
3 to 5 times more efficient than the typical incandescent lamp runing in the
15 lumens/w range.

If this is indeed a CCFL (cold cathode fluorescent) rather than a
usual hot cathode hot cathode CFL, expect efficiency a little to somewhat
less than that of the usual hot cathode ones.

Decent hot cathode CFLs around 8-9 watts achieve about 50
lumens/watt and produce roughly as much light as most 40 watt
incandescents.

- Don Klipstein ([email protected])

 

[Victor Roberts]

Hi all,

What is the efficency of a cold cathod tubular bulb ? Is a 8W CCFL worth
the light output of a 80W plain old incandescent bulb ?

First of all, no fluorescent lamp I know of is 10 times as
efficient as an ordinary 80 -watt incandescent lamp would be
if there were such a lamp. (I am using 75-watt and 100-watt
incandescent lamps as my benchmark.) Very good fluorescent
lamps are about 6 times as efficient as 75-watt and 100-watt
120-volt incandescent lamps, and perhaps 7.5 times as
efficient as 100-watt 230-volt incandescent lamps,

Second, cold cathode fluorescent lamps are significantly
less efficient than thermionic (hot) cathode fluorescent
lamps UNLESS they have a high length-to-diameter ratio. If
that is the case, they will have about the same efficacy as
a hot cathode fluorescent lamp. The reason for the low
efficacy of CCFLs with low length-to-diameter ratios is the
very high voltage drop between the discharge and the cold
electrode, compared to the much lower voltage drop between
the discharge and a thermionic cathode. This high voltage
drop can only be offset with a very high positive column
voltage. High positive column voltage drops are present in
lamps that have high length-to-diameter ratios.

--
Vic Roberts
http://www.RobertsResearchInc.com
To reply via e-mail:
replace xxx with vdr in the Reply to: address
or use e-mail address listed at the Web site.

This information is provided for educational purposes only.
It may not be used in any publication or posted on any Web
site without written permission.

 

[BobT]

First of all, no fluorescent lamp I know of is 10 times as
efficient as an ordinary 80 -watt incandescent lamp would be
if there were such a lamp. (I am using 75-watt and 100-watt
incandescent lamps as my benchmark.) Very good fluorescent
lamps are about 6 times as efficient as 75-watt and 100-watt
120-volt incandescent lamps, and perhaps 7.5 times as
efficient as 100-watt 230-volt incandescent lamps,

These numbers raise a question. Are plain old mass-market spiral
CFL's pretty far below your "very good" lamps noted above?

Looking at what I have in the basement, standard brand (Chinese GE)
CFL's rated 6 watts are marketed as 40 watt equivalent; 13W as 60's,
20W as 75's, 26W as 100's, and both 42W and 45W as 150's. All these
numbers are in the vicinity of 4 times as efficient. Are CFL's
inherently less efficient than your benchmark "good" lamps?

 

[artis sideley]

Don Klipstein a écrit :

If this is indeed a CCFL (cold cathode fluorescent) rather than a
usual hot cathode hot cathode CFL, expect efficiency a little to somewhat
less than that of the usual hot cathode ones.

Decent hot cathode CFLs around 8-9 watts achieve about 50
lumens/watt and produce roughly as much light as most 40 watt
incandescents.

- Don Klipstein ([email protected])

Thanks,

I knew the effective efficacy of Hot cathode CFL but I have no
experience of CCFL as domestic lighting. So far, the only CCFL I know
are used in LCD displays and as coloured advertising displays, those are
rather efficiency poor.

The commercial is deceptive then.

 

[Victor Roberts]

These numbers raise a question. Are plain old mass-market spiral
CFL's pretty far below your "very good" lamps noted above?

Yes. I was referring to 4-foot linear T8 lamps. Spiral
lamps have lower efficacy both because their diameter is
smaller than optimum for the power levels they operate at,
and the spiral design traps light.

Looking at what I have in the basement, standard brand (Chinese GE)
CFL's rated 6 watts are marketed as 40 watt equivalent; 13W as 60's,
20W as 75's, 26W as 100's, and both 42W and 45W as 150's. All these
numbers are in the vicinity of 4 times as efficient. Are CFL's
inherently less efficient than your benchmark "good" lamps?

Yes, for the reasons mentioned above.

--
Vic Roberts
http://www.RobertsResearchInc.com
To reply via e-mail:
replace xxx with vdr in the Reply to: address
or use e-mail address listed at the Web site.

This information is provided for educational purposes only.
It may not be used in any publication or posted on any Web
site without written permission.