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Home > Archive > Electrical Engineering > April 2006 > Dimming domestic CFLs safely
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Dimming domestic CFLs safely
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| I want to replace some of the GLS bulbs at home with compact
fluorescent bulbs. Several of the CFL bulbs I have a bargain
basement ones whose light seem surprisingly acceptable. They are
this sort which I see is called "biax". I am in the UK so, of
course, my home light bulbs use a bayonet fitting.
<http://upload.wikimedia.org/wikiped...act_flourescent
_straight.JPG>
Many of my room switches have a dimmer built in. Is it all right
to use a dimmer with this sort of CFL if I make sure the CFL does
not actually go out?
I have read Don Klipstein's pages about fluorescents in general:
--------------------- QUOTE ---------------------------
If you reduce power to the lamp, the filaments will not be as hot,
and will not be able to thermionically emit electrons as easily.
If the filaments get too cool by dimming the lamp greatly, usually
the lamp will just go out. If you force current to continue
flowing while the electrodes are at an improper temperature, then
severe rapid degradation of the thermionic material on the
filaments is likely.
....
Reducing the voltage to most ordinary fluorescent fixtures seems
to be largely successful for a small amount of dimming, up to 30
to 50 percent dimming. This seems to usually work for preheat
fixtures and rapid start fixtures of 40 watts or less.
http://members.misty.com/don/f-dim.html
--------------------- UNQUOTE ---------------------------
However I'm not clear what sort of starter or tube is usually used
in my biax CFL.
Don refers to 30 or 50% being possible without problem. Would
this figure also apply to my biax CFLs?
If I IN-correctly set my dimmers such that the biax CFLs do not
light up then is there any danger to the dimmer itself (or even to
the house wiring)?
| |
| Andrew Gabriel 2006-04-14, 8:21 pm |
| In article <Xns97A5E724DCB7B74C1H4@127.0.0.1>,
Andy <nomail@nomail.com> writes:
> I want to replace some of the GLS bulbs at home with compact
> fluorescent bulbs. Several of the CFL bulbs I have a bargain
> basement ones whose light seem surprisingly acceptable. They are
> this sort which I see is called "biax". I am in the UK so, of
> course, my home light bulbs use a bayonet fitting.
I don't know of any dimmable ones. They exist in the US market
but not the UK market.
You can get 4-pin compact fluorescents to run from separate
electronic control gear, and there are dimmable versions of
this available. However, they won't run from a standard
filament lamp dimmer, and make sure you are sitting down
when they quote you a price...
> Many of my room switches have a dimmer built in. Is it all right
> to use a dimmer with this sort of CFL if I make sure the CFL does
> not actually go out?
No.
> I have read Don Klipstein's pages about fluorescents in general:
> However I'm not clear what sort of starter or tube is usually used
> in my biax CFL.
I think Don is referring to traditional fluorescent lamps
with separate control gear.
--
Andrew Gabriel
| |
| meow2222@care2.com 2006-04-14, 10:21 pm |
| Andy wrote:
> I want to replace some of the GLS bulbs at home with compact
> fluorescent bulbs. Several of the CFL bulbs I have a bargain
> basement ones whose light seem surprisingly acceptable. They are
> this sort which I see is called "biax". I am in the UK so, of
> course, my home light bulbs use a bayonet fitting.
>
> <http://upload.wikimedia.org/wikiped...act_flourescent
> _straight.JPG>
>
> Many of my room switches have a dimmer built in. Is it all right
> to use a dimmer with this sort of CFL if I make sure the CFL does
> not actually go out?
if you keep the dmimer at full its fine, but if you turn it down you
can expect the cfls to die early. Not a safety issue.
NT
| |
| Ian Stirling 2006-04-15, 7:21 am |
| In sci.engr.lighting Andrew Gabriel <andrew@cucumber.demon.co.uk> wrote:
> In article <Xns97A5E724DCB7B74C1H4@127.0.0.1>,
> Andy <nomail@nomail.com> writes:
>
> I don't know of any dimmable ones. They exist in the US market
> but not the UK market.
There was a link posted a few months ago, to ones in the UK.
Only several levels of dimming, rather than variable, but still
dimmable.
| |
| Christian Koch 2006-04-15, 8:21 am |
| Andrew Gabriel <andrew@cucumber.demon.co.uk> wrote:
> In article <Xns97A5E724DCB7B74C1H4@127.0.0.1>,
> Andy <nomail@nomail.com> writes:
>
> I don't know of any dimmable ones. They exist in the US market
> but not the UK market.
Osram announced the Dulux EL Dim for spring 2006:
<http://www.osram.com/products/gener...html#duluxeldim>
It is already available here in Germany for about 20 EUR/pcs.
Christian.
| |
| Victor Roberts 2006-04-15, 11:21 am |
| On Fri, 14 Apr 2006 22:43:20 +0100, Andy <nomail@nomail.com>
wrote:
>I want to replace some of the GLS bulbs at home with compact
>fluorescent bulbs. Several of the CFL bulbs I have a bargain
>basement ones whose light seem surprisingly acceptable. They are
>this sort which I see is called "biax". I am in the UK so, of
>course, my home light bulbs use a bayonet fitting.
>
><http://upload.wikimedia.org/wikiped...act_flourescent
>_straight.JPG>
>
>Many of my room switches have a dimmer built in. Is it all right
>to use a dimmer with this sort of CFL if I make sure the CFL does
>not actually go out?
In the US most CFLs have a clear statement on the lamp that
they are NOT compatible with dimmers. A few are designed
for use with dimmers and that is stated on the box or the
lamp.
I don't know how lamps are labeled in the UK, but I suspect
they are not suitable for use with dimmers unless they state
so on the lamp or box. You run the risk of destroying the
dimmer and/or the lamp if you use these lamps with a dimmer.
--
Vic Roberts
http://www.RobertsResearchInc.com
To reply via e-mail:
replace xxx with vdr in the Reply to: address
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This information is provided for educational purposes only.
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| |
| Robbie McFerren 2006-04-15, 12:21 pm |
| Dimmer destruction is more than likely. If the lamps are corrected for
power factor by a capacitor then the dimmer will fail with some nice
fireworks even if the dimmer is set to the full on position.
Victor Roberts wrote:
> On Fri, 14 Apr 2006 22:43:20 +0100, Andy <nomail@nomail.com>
> wrote:
>
>
> In the US most CFLs have a clear statement on the lamp that
> they are NOT compatible with dimmers. A few are designed
> for use with dimmers and that is stated on the box or the
> lamp.
>
> I don't know how lamps are labeled in the UK, but I suspect
> they are not suitable for use with dimmers unless they state
> so on the lamp or box. You run the risk of destroying the
> dimmer and/or the lamp if you use these lamps with a dimmer.
| |
| Victor Roberts 2006-04-15, 1:21 pm |
| On Sat, 15 Apr 2006 10:34:31 -0400, Robbie McFerren
<robbie.mcferren@bluebottle.com> wrote:
>Dimmer destruction is more than likely. If the lamps are corrected for
>power factor by a capacitor then the dimmer will fail with some nice
>fireworks even if the dimmer is set to the full on position.
CFLs with electronic ballasts (just about the only type
available today) never use a parallel capacitor for power
factor correction. The problem is that LOW power factor
CFLs use a full-wave rectifier feeding a large electrolytic
energy storage capacitor. It is this capacitor that
destroys the phase-cut dimmer. However, certain dimmers
have a set of mechanical contacts that close whenever dimmer
is full on, bypassing the Triac. If a dimmer of this type
is turned to full on, it will not be damaged by a low power
factor CFL. However, as the user cannot guarantee that the
dimmer setting will not be changed, use of any type of
dimmer is not recommended with a low power factor CFL.
All dimmable CFLs are high power factor and use active power
factor correction.
--
Vic Roberts
http://www.RobertsResearchInc.com
To reply via e-mail:
replace xxx with vdr in the Reply to: address
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| |
| Robbie McFerren 2006-04-15, 2:21 pm |
| Are the power factor correction electronics is the only difference
between dimmable CFLs and regular CFLs? If that is the only difference
I don't see why they can't be dimmed by old fashioned variac dimmers.
Victor Roberts wrote:
> On Sat, 15 Apr 2006 10:34:31 -0400, Robbie McFerren
> <robbie.mcferren@bluebottle.com> wrote:
>
>
> CFLs with electronic ballasts (just about the only type
> available today) never use a parallel capacitor for power
> factor correction. The problem is that LOW power factor
> CFLs use a full-wave rectifier feeding a large electrolytic
> energy storage capacitor. It is this capacitor that
> destroys the phase-cut dimmer. However, certain dimmers
> have a set of mechanical contacts that close whenever dimmer
> is full on, bypassing the Triac. If a dimmer of this type
> is turned to full on, it will not be damaged by a low power
> factor CFL. However, as the user cannot guarantee that the
> dimmer setting will not be changed, use of any type of
> dimmer is not recommended with a low power factor CFL.
>
> All dimmable CFLs are high power factor and use active power
> factor correction.
>
| |
| Andrew Gabriel 2006-04-15, 3:21 pm |
| In article <e1r7tr$rrm$1@emma.aioe.org>,
Robbie McFerren <robbie.mcferren@bluebottle.com> writes:
> Are the power factor correction electronics is the only difference
> between dimmable CFLs and regular CFLs?
If they work the way I suspect they do, there is no "power factor
correction electronics". It's just a feature of the SMPSU inside
them that they have pretty much unity power factor without needing
any correction -- it's a side effect of needing to track the dimmer's
phase angle switching.
> If that is the only difference
> I don't see why they can't be dimmed by old fashioned variac dimmers.
Your assumption that the light output will be any useful
function of the supply voltage is unlikely to match reality.
If you simply cut the storage capacitor out of a standard CFL, you
may find you now have a dimmable one. The snag is it will likely
only have something like 30-60% dimming range, with no ability to
run at full output.
--
Andrew Gabriel
| |
| Victor Roberts 2006-04-15, 3:21 pm |
| On Sat, 15 Apr 2006 12:45:20 -0400, Robbie McFerren
<robbie.mcferren@bluebottle.com> wrote:
>Are the power factor correction electronics is the only difference
>between dimmable CFLs and regular CFLs?
The first requirement is that are high power factor so the
dimmer can work with Triac dimmers
>If that is the only difference
>I don't see why they can't be dimmed by old fashioned variac dimmers.
The second requirement is that the inverter be designed to
operate correctly over a range of DC supply voltages.
You do not need HPF to use a Variac, but if the inverter is
not designed correctly, then it will not operate correctly
as you change the internal DC voltage with the Variac.
[color=darkred]
>Victor Roberts wrote:
--
Vic Roberts
http://www.RobertsResearchInc.com
To reply via e-mail:
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It may not be used in any publication or posted on any Web
site without written permission.
| |
| Victor Roberts 2006-04-15, 3:21 pm |
| On 15 Apr 2006 17:30:12 GMT, andrew@cucumber.demon.co.uk
(Andrew Gabriel) wrote:
>In article <e1r7tr$rrm$1@emma.aioe.org>,
> Robbie McFerren <robbie.mcferren@bluebottle.com> writes:
>
>If they work the way I suspect they do, there is no "power factor
>correction electronics". It's just a feature of the SMPSU inside
>them that they have pretty much unity power factor without needing
>any correction -- it's a side effect of needing to track the dimmer's
>phase angle switching.
SMPSU ??? The systems I have seen are FIRST designed to
have a high power factor input. That enables the use of a
phase-cut Triac dimmer. In these systems, the internal DC
voltage will vary with the setting of the dimmer. THEN, the
inverter is designed to operate correctly over a wide range
of DC power supply voltage.
>
>Your assumption that the light output will be any useful
>function of the supply voltage is unlikely to match reality.
>
>If you simply cut the storage capacitor out of a standard CFL, you
>may find you now have a dimmable one. The snag is it will likely
>only have something like 30-60% dimming range, with no ability to
>run at full output.
If you simply cut out the energy storage capacitor, the
output will be highly modulated at 100 or 120 Hz and there
is no assurance that the inverter will work correctly as the
DC voltage is varied.
--
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.
| |
| Ian Stirling 2006-04-15, 7:21 pm |
| In sci.engr.lighting Robbie McFerren <robbie.mcferren@bluebottle.com> wrote:
> Are the power factor correction electronics is the only difference
> between dimmable CFLs and regular CFLs? If that is the only difference
> I don't see why they can't be dimmed by old fashioned variac dimmers.
<snip quoted message incorrectly placed at bottom>
No.
Basically, a CFL is a power supply.
It's designed to output 0.2A (or whatever) into a voltage of 70V
(example, a guess).
If you vary the input voltage (with a variac), unless it's designed to
behave nicely, and properly dim the light (which when a current of 0.1A
flows will want 90V), it's probably just going to give up.
Random datapoint.
A "PHILIPS Genie 6Yr 11W Energy Saver 230-240V 50-60Hz", on gradually
the DC supply voltage, strikes at 82V.
At 150V, it's using 9W of electricity, where my PSU runs out.
It does sort-of-dim, but not very much.
On dropping the voltage, it's still producing light at 60V, more or less
normally, finally going out at 40V.
Interestingly, observing the heater drive, on varying the voltage,
it drops, then recovers to its original level.
Spiking the voltage to 300V, with a large flying capacitor, the heater
voltage is still about the same.
This _may_ suggest that it's not going to get absolutely horrible life,
when underdriven.
The lamp voltage, as expected, rises as the input voltage drops.
| |
| Ian Stirling 2006-04-15, 7:21 pm |
| In sci.engr.lighting Ian Stirling <root@mauve.demon.co.uk> wrote:
> In sci.engr.lighting Robbie McFerren <robbie.mcferren@bluebottle.com> wrote:
>
> <snip quoted message incorrectly placed at bottom>
>
> No.
> Basically, a CFL is a power supply.
> It's designed to output 0.2A (or whatever) into a voltage of 70V
> (example, a guess).
>
> If you vary the input voltage (with a variac), unless it's designed to
> behave nicely, and properly dim the light (which when a current of 0.1A
> flows will want 90V), it's probably just going to give up.
>
> Random datapoint.
> A "PHILIPS Genie 6Yr 11W Energy Saver 230-240V 50-60Hz", on gradually
> the DC supply voltage, strikes at 82V.
> At 150V, it's using 9W of electricity, where my PSU runs out.
6W, measurement error.
I'll measure it at nominal tomorrow.
| |
|
| On 14 Apr 2006, Andy<nomail@nomail.com> wrote:
>
> I want to replace some of the GLS bulbs at home with compact
> fluorescent bulbs. Several of the CFL bulbs I have a bargain
> basement ones whose light seem surprisingly acceptable.
> Many of my room switches have a dimmer built in. Is it all right
> to use a dimmer with this sort of CFL if I make sure the CFL does
> not actually go out?
Thank you for the feedback guys.
So it's going to be a "no". Oh well!
| |
| Andrew Gabriel 2006-04-16, 5:21 am |
| In article <a3c2429sincekio8ulc2icocnlpnoc1n6b@4ax.com>,
Victor Roberts <xxx@lighting-research.com> writes:
> On 15 Apr 2006 17:30:12 GMT, andrew@cucumber.demon.co.uk
> (Andrew Gabriel) wrote:
>
>
> SMPSU ??? The systems I have seen are FIRST designed to
> have a high power factor input. That enables the use of a
> phase-cut Triac dimmer. In these systems, the internal DC
> voltage will vary with the setting of the dimmer. THEN, the
> inverter is designed to operate correctly over a wide range
> of DC power supply voltage.
The high power factor SMPSU's I've seen (not in CFLs admittedly)
seem to have a first stage which is simply missing the initial
storage capacitor so they draw current over most of the waveform
instead of just at the peaks. Energy storage to tide over the zero
crossing region is then further downline.
>
> If you simply cut out the energy storage capacitor, the
> output will be highly modulated at 100 or 120 Hz and there
Just like a conventional fluorescent lamp.
> is no assurance that the inverter will work correctly as the
> DC voltage is varied.
This is behaviour I have observed when the storage capacitor
has failed in CFLs. There is indeed no assurance, which is why
I said _may_.
--
Andrew Gabriel
| |
| Victor Roberts 2006-04-16, 12:21 pm |
| On 16 Apr 2006 07:44:43 GMT, andrew@cucumber.demon.co.uk
(Andrew Gabriel) wrote:
>In article <a3c2429sincekio8ulc2icocnlpnoc1n6b@4ax.com>,
> Victor Roberts <xxx@lighting-research.com> writes:
>
>The high power factor SMPSU's I've seen (not in CFLs admittedly)
>seem to have a first stage which is simply missing the initial
>storage capacitor so they draw current over most of the waveform
>instead of just at the peaks. Energy storage to tide over the zero
>crossing region is then further downline.
I still don't know what you mean by SMPSU other than I
suppose it is some type of power supply unit.
Yes, you can just remove the energy storage capacitor, but
that will also remove about have the efficacy advantage of
high frequency operation of fluorescent lamps. There has
been a lot of work done on high power factor inverters that
ALSO produce relatively ripple-free DC voltage. Early
designs required two power stages, which increased the cost
and decreased the efficacy. Later, single-stage high power
factor inverters were developed.
A good review can be found in the PhD thesis of Jinrong
Qian:
http://scholar.lib.vt.edu/theses/av...ed/graduate.pdf
Figure 6.8c of Qian's theses (page 154) is similar to the
ballasts used in many high power factor CFLs. Note that the
lamp current is returned to the junction of two small
capacitors that are connected between the full wave
rectifier and the single energy storage capacitor. This
allows these small capacitors to extract energy from the
power line when it is low and push it into the energy
storage capacitors which have a higher voltage at that
instant of time.
--
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.
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It may not be used in any publication or posted on any Web
site without written permission.
| |
| Victor Roberts 2006-04-16, 1:21 pm |
| On Sun, 16 Apr 2006 10:41:05 -0400, Victor Roberts
<xxx@lighting-research.com> wrote:
>Yes, you can just remove the energy storage capacitor, but
>that will also remove about have the efficacy advantage of
>high frequency operation of fluorescent lamps.
The above was supposed to read: Yes, you can remove the
energy storage capacitor, but that will also remove about
half the energy advantage of high frequency operation.
>There has
>been a lot of work done on high power factor inverters that
>ALSO produce relatively ripple-free DC voltage. Early
>designs required two power stages, which increased the cost
>and decreased the efficacy. Later, single-stage high power
>factor inverters were developed.
--
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.
| |
| Victor Roberts 2006-04-16, 5:21 pm |
| On Sun, 16 Apr 2006 10:41:05 -0400, Victor Roberts
<xxx@lighting-research.com> wrote:
[snip]
>
>I still don't know what you mean by SMPSU other than I
>suppose it is some type of power supply unit.
>
>Yes, you can just remove the energy storage capacitor, but
>that will also remove about have the efficacy advantage of
>high frequency operation of fluorescent lamps. There has
>been a lot of work done on high power factor inverters that
>ALSO produce relatively ripple-free DC voltage. Early
>designs required two power stages, which increased the cost
>and decreased the efficacy. Later, single-stage high power
>factor inverters were developed.
>
>
>A good review can be found in the PhD thesis of Jinrong
>Qian:
>
>http://scholar.lib.vt.edu/theses/av...ed/graduate.pdf
>
>Figure 6.8c of Qian's theses (page 154) is similar to the
>ballasts used in many high power factor CFLs. Note that the
>lamp current is returned to the junction of two small
>capacitors that are connected between the full wave
>rectifier and the single energy storage capacitor. This
>allows these small capacitors to extract energy from the
>power line when it is low and push it into the energy
>storage capacitors which have a higher voltage at that
>instant of time.
See also US 6,998,795, which is available at www.uspto.gov.
This ballast users a valley-fill circuit combined with a
charge pump.
--
Vic Roberts
http://www.RobertsResearchInc.com
To reply via e-mail:
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| |
| Victor Roberts 2006-04-16, 6:21 pm |
| On Sun, 16 Apr 2006 15:33:07 -0400, Victor Roberts
<xxx@lighting-research.com> wrote:
>See also US 6,998,795, which is available at www.uspto.gov.
>This ballast users a valley-fill circuit combined with a
>charge pump.
My typing is terrible. "This ballast USES a valley-fill
circuit combined with a charge pump.
--
Vic Roberts
http://www.RobertsResearchInc.com
To reply via e-mail:
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