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Switches and CFL lamps

J

Jeff Layman

Jan 1, 1970
0
Switches intended for use with lighting (timers, PIR, photocells) warn
against use with CFLs, and state that filament lamps should be used. Why?
It shouldn't make any difference whether a relay or triac (with ZCD
circuitry) is used to switch the lamp on/off the lamp. I've used a couple of
timers with a CFL for years without any apparent problem.

And if there is a problem I am unaware of, what will we be able to use when
the filament lamps are taken off the market in the EU in a few years time?
 
S

Sjouke Burry

Jan 1, 1970
0
Jeff said:
Switches intended for use with lighting (timers, PIR, photocells) warn
against use with CFLs, and state that filament lamps should be used. Why?
It shouldn't make any difference whether a relay or triac (with ZCD
circuitry) is used to switch the lamp on/off the lamp. I've used a couple of
timers with a CFL for years without any apparent problem.

And if there is a problem I am unaware of, what will we be able to use when
the filament lamps are taken off the market in the EU in a few years time?
A CFL starts with a huge current pulse charging the main
supply cap inside.
Not all switches like that.
 
P

petrus bitbyter

Jan 1, 1970
0
Sjouke Burry said:
A CFL starts with a huge current pulse charging the main
supply cap inside.
Not all switches like that.

Maybe but I doubt it. Cold filament lamps start with a high inrush peak
current too. For all I can imagine switching off a CFL with a classic
ballast may cause problems. Switching on/off modern "energy saving" CFLs
should not do worse then filament bulbs. Dimmers are different and I think
the warning not to use CFLs in timers and the like comes from that dimmers.
The manufacturers simply stay on the safe side to avoid claims. After all
the behavior of filament bulbs is well known but they can't be sure of the
electronics that are put in CFLs. As for abandonning filament bulbs, I
expect LED lights to push aside both CFLs and filament lamps in next years.

petrus bitbyter
 
D

Don Klipstein

Jan 1, 1970
0
Maybe but I doubt it. Cold filament lamps start with a high inrush peak
current too.

Cold filaments draw peak current something like 20 times their RMS
current, depending on when in an AC half-cycle they are switched on. CFLs
often draw much more than that, with peak current limited by line
impedance and the impedance of the bridge rectifier, filter capacitor, and
a small RF choke. Sounds to me like an ohm or two.
For all I can imagine switching off a CFL with a classic
ballast may cause problems. Switching on/off modern "energy saving" CFLs
should not do worse then filament bulbs. Dimmers are different and I think
the warning not to use CFLs in timers and the like comes from that dimmers.
The manufacturers simply stay on the safe side to avoid claims.

Probably a good idea for consumers also. I would not like to have to
explain to a fire insurance company why I was using electrical equipment
other than as directed, even if the fire started for a reason other than
the fact that the equipment was being used in a way that was warned
against.

- Don Klipstein ([email protected])
 
I

IanM

Jan 1, 1970
0
Don said:
Cold filaments draw peak current something like 20 times their RMS
current, depending on when in an AC half-cycle they are switched on. CFLs
often draw much more than that, with peak current limited by line
impedance and the impedance of the bridge rectifier, filter capacitor, and
a small RF choke. Sounds to me like an ohm or two.




Probably a good idea for consumers also. I would not like to have to
explain to a fire insurance company why I was using electrical equipment
other than as directed, even if the fire started for a reason other than
the fact that the equipment was being used in a way that was warned
against.

There is also the observed fact that for many CFLs, any small leakage
current through or across the switch will cause the CFL's reservoir
capacitor to charge until there is enough voltage for the inverter
circuit to start, thus the lamp tends to flash. I have seen this happen
with just the capacitance between two parallel wires (in the same cable)
in stairway lighting circuits. I wonder what effect on the safety and
reliability of the lamp many thousands of repeated starts a day has?

Failure modes for a normal lightbulb tend to be short (often with a
momentary arc) - usually protected by an integral fuse, open, and
envelope rupture. In a normal operating environment, none are
particularly hazardous. Perhaps CFLs have a failure mode that involves
dangerous overheating on startup so require a human present to check
they have turned on safely?
 
D

Don Klipstein

Jan 1, 1970
0
There is/was some good info on flouro lights,and CFL's here:
http://sound.westhost.com/lamps/index.html
I can't seem to find the article I'm thinking of,however.

I am finding some flawed measurements, such as in:

http://sound.westhost.com/lamps/fluorescent.html

That page claims that an LED tube light produces more than twice as much
light per watt than fluorescents that it replaces, on basis of power
consumption and lux on a benchtop under the light.
However, the LED tube light is probably illuminating a smaller area than
the fluorescents did.

If you find benefit from making a light source directional, there is
such a thing as reflectors. With a suitable reflector, a decent fluorescent
will have the same directional pattern as the LED tube light and provide
similar (more likely greater) lux per watt than the LED tube light.

I am also finding some flawed data, as in:

http://sound.westhost.com/articles/incandescent.htm

That page has a table showing supposed overall luminous efficacies of
various light sources.

It shows 17.5 lumens/watt for 100 watt incandescent - that is top end
for 100W non-halogen 120V incandescent. And top end 230V 100W ones do not
achieve that, due to economies of scale on the thinner filament.

A few paragraphs later that page says a 100 watt incandescent produces
1800 lumens but clams CFL manufacturers are claiming 1246 lumens as
equivalent to 100W. In what country? Many European and Australian 100W
incandescents do only produce 1200-1400 lumens. 100W incandescents that
get referred to as GLS lamps (a term used on that page and where
household voltage is 230V) do not produce 1750-1800 lumens, and even USA
ones don't produce 1800 lumens.

Same story for the 40 watt incandescent.

It also shows 93 lumens/watt as "max, typical" for 36 watt T8
fluorescent. Keep in mind a couple things:

1. Most countries where most household incandescents are designed for
120V have T8 4-foot fluorescents mainly being 32 watt ones, and where
36 watts if the wattage of most T8 fluorescents most incandescents are
rated for 230V.

2. Catalog watt and lumen figures for T8 fluorescents are with line
frequency magnetic ballasts, while catalog figures for modern T5
fluorescents is with high frequency electronic ballasts. But most 32 watt
T8 fluorescents are used with high frequency electronic ballasts, which
largely eliminates one loss of most fluorescent lamps and reduces another.
I suspect that in new fixtures in Europe with 36 watt lamps, the ballasts
are probably mostly electronic.

The same table says 24 lumens/watt for halogen. Most rated at least
2,000 hours and drawing 2.5 amps or less achieve 21 or less.

That page also mentions some fixtures to not use any CFLs in. However,
some CFLs, such as Philips "triple arch" 15, 20 and 23 watt non-dimmable,
are specifically rated to be OK in recessed ceiling fixtures.

That page claims that CFLs emit significantly more UV than
incandescents. I have found that to hardly be true. And that page claims
that the UV increases risk of *breast* cancer?

That page also mentions problems from CFLs taking 5 minutes to warm up.
Ones without outer bulbs generally take more like 1 minute to be most of
the way warmed up.

I sense anti-fluorescent bias.

- Don Klipstein ([email protected])
 
J

Jeff Layman

Jan 1, 1970
0
Peter Hucker wrote:
(snip)
LEDs WILL take over our lighting. They may need to get more
efficient first though. They already have advantages in things like
traffic light5s and cars, as they don't need changing so often, and
are instant on/off.

I am sure that they will. But I'm not so sure about their predicted life
(compare what is still being said about CFLs with real-life experience).
The high-power LEDs do run really hot, and need a good-sized heatsink to
deal with the waste heat. No good adding fans to cool them, as they aren't
reliable enough for really long-term usage.

Of course it may be that semiconductor LEDs will be superseded by OLEDs.
Not for every use, perhaps, but where one needs diffuse lighting they will
be OK. I can foresee the time when we don't have luminaires as such - the
whole ceiling (and perhaps walls) will be a light emitter.
 
J

Jeff Layman

Jan 1, 1970
0
Peter said:
When they become more efficient, there will be less heat output.

What about a heat pipe like thy use in computers?

Too expensive.
From wikipedia: "The biggest technical problem for OLEDs is the
limited lifetime of the organic materials. In particular, blue OLEDs
historically have had a lifetime of around 14,000 hours"

But see
http://www.osram-os.com/osram_os/EN...c_LED/Press-release-OPAL-research-project.jsp

True, the life isn't that good yet (although 5000+ hours isn't bad), but
look at the lm/W figure, and what is projected for next March. ISTM that
OLEDs are in the stage of development that LEDs were in a couple of years
ago, but are catching up fast.
 
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