Constant Voltage Transformer Question

Greg Neff · Jan 1, 2005

On 31 Dec 2004 13:22:03 -0800, Winfield Hill
<hill_a@t_rowland-dotties-harvard-dot.s-edu> wrote:

Jim Thompson wrote...

I was wondering how Constant Voltage Transformers would perform with
lamp loads. I'm thinking of room-by-room regulation for ceiling
fixtures... since, 15' up, it's tricky with a lamp changer pole :-(

Why not change to electronic mini-fluorescent lamps? I'd imagine
they aren't very voltage sensitive and now they're available with
decent color-temperature phosphors, and some can work with dimmers.
Save on electricity, cooling energy, and manpower.

Colour temperature is a problem, especially when mixing lamp types.
We have found that the lamp colour temperature makes a huge difference
in the appearance of wall paint colour, and a mismatch of lighting
makes a room look strange.

In our kitchen we have 4' fluorescent tubes in part of the kitchen,
and a 3-lamp ceiling-mounted fixture in the eating area. We had a
heck of a time finding CFLs with a comparable colour temperature. All
warm-white CFLs are no good. I tried a GE CFL with a 6500K (IIRC)
temperature, but its light output had a very strong and unpleasant
blue component. We ended up using Panasonic "cool white" EFD14E50
lamps (colour temp 5000K). Something with just a touch lower colour
temperature would be ideal.

In our living/dining room and halls we have a mix of incandescent and
"warm white" CFLs. At first we had some Globe Electric CFLs, and the
colour match was excellent. Unfortunately, we had to dispose of them
because of a UL fire hazard warning. We purchased another brand
"Commercial Electric" a.k.a. "Technical Consumer Products", but these
have a noticeably higher colour temperature. So, we will have to try
yet another brand.

If I were GE or Philips or whatever, I would develop and promote
matched pairs. I would market cool white CFLs and fluorescent tubes
with the same colour temperature, and I would market warm white CFLs
and incandescent lamps with the same colour temperature. This would
save me alot of time and money trying to match these on my own.

CFLs with problems:

http://www.ul.com/media/newsrel/nr102604.html
http://www.cpsc.gov/cpscpub/prerel/prhtml05/05064.html
http://www.cpsc.gov/cpscpub/prerel/prhtml05/05005.html

Links:

http://www.ge.com/en/product/home/lighting.htm
http://www2.panasonic.com/webapp/wcs/stores/servlet/vModelList?storeId=11251&catalogId=11005&langId=-1&catGroupId=11288
http://www.globe-electric.com/
http://www.tcpi.com
http://www.sylvania.com/ConsumerProducts/LightingForHome/Products/BulbType/CompactFluorescent
http://www.nam.lighting.philips.com/can/consumer/products_marathon_ES.php

================================

Greg Neff
VP Engineering
*Microsym* Computers Inc.
greg@guesswhichwordgoeshere.com

Jim Thompson · Jan 1, 2005

On Sat, 01 Jan 2005 00:50:05 -0500, **THE-RFI-EMI-GUY**
<rhyolite@nettally.com> wrote:

Are they blowing up on turn on or is it when the voltage surges? If its
the former, most likely, why not rig up a dimmer circuit with a shunt
relay with a delay-on timer of say 5 seconds. Then everytime the
circuit is turned on, the lamps will soft start for a few seconds giving
the filaments time to warm up a bit.

The RFI-EMI-GUY

[snip]

480)460-2350 | |
| E-mail Address at Website Fax

Bennett Price · Jan 1, 2005

Just don't try to use CVT with fluorescent lights; they may not start.
CVT is fine for incandescent.

Jim Thompson wrote:

A major pain-in-the-ass in Arizona is lightbulb lifetime, particularly
this time of year, where one day will require heat and the next not.

So the AC voltage regulation sucks... often popping up to 130VRMS.

I was wondering how Constant Voltage Transformers would perform with
lamp loads.

I'm thinking of room-by-room regulation for ceiling fixtures... since,
15' up, it's tricky with a lamp changer pole :-(

I have easy attic access, pull-down-stair ladders, and the attic is
tall enough that I can stand upright to work in most locations.

...Jim Thompson

John Woodgate · Jan 1, 2005

I read in sci.electronics.design that Greg Neff <greg@guesswhichwordgoes
here.com> wrote (in <g3jdt05mst3ultp6fogrn1o4jj777nf5ms@4ax.com&gt

about
'Constant Voltage Transformer Question', on Sat, 1 Jan 2005:

All warm-white
CFLs are no good.

I think you probably mean that 'not all are good', rather than 'all are
no good'.

I tried a GE CFL with a 6500K (IIRC) temperature, but
its light output had a very strong and unpleasant blue component.

6500 K is US daylight and is indeed too blue for use in the home. Ideal
for colour-matching and some benchwork.

We
ended up using Panasonic "cool white" EFD14E50 lamps (colour temp
5000K). Something with just a touch lower colour temperature would be
ideal.

5000 K is British daylight, and is beyond reproach. (;-)

In our living/dining room and halls we have a mix of incandescent and
"warm white" CFLs. At first we had some Globe Electric CFLs, and the
colour match was excellent. Unfortunately, we had to dispose of them
because of a UL fire hazard warning. We purchased another brand
"Commercial Electric" a.k.a. "Technical Consumer Products", but these
have a noticeably higher colour temperature. So, we will have to try
yet another brand.

I'm not keen on European 'warm white': it doesn't seem bright enough for
me. I use cool white CFLs and fluorescents wherever possible.

If I were GE or Philips or whatever, I would develop and promote matched
pairs. I would market cool white CFLs and fluorescent tubes with the
same colour temperature,

AIUI, that's what they think they do.

and I would market warm white CFLs and
incandescent lamps with the same colour temperature.

Incandescent lamps (gas-filled) are around 3500 K. I don't think I'd
like a CFL as yellow as that. European warm white is spectrally skewed,
so it's not really possible to assign a colour temperature to it.

--
Regards, John Woodgate, OOO - Own Opinions Only.
The good news is that nothing is compulsory.
The bad news is that everything is prohibited.
http://www.jmwa.demon.co.uk Also see http://www.isce.org.uk

Nicholas O. Lindan · Jan 1, 2005

"James Meyer" <jmeyer@nowhere.net> wrote

Ferroresonant transformers have terrible efficiencies.

Well, yes and no.

They draw the same current from the line at full load and
no load. When used at nameplate rating they are 90% efficient.

At no load most of the current draw is reactive. However, there
are huge core losses in the beasts as they run half the core into
saturation.

If you want to double your power usage, they're great!

With a 50% load that's about what will happen.

If you are in the far north and only need light in the winter
when you also needs lots of heat they'll work just fine.

In Arizona ... probably not a good solution.

OTOH: Very reliable, 1% line regulation on the fancy models,
one of the best protectors against power spikes/surges/nearby
lightning strikes. Cheap on ebay.

--
Nicholas O. Lindan, Cleveland, Ohio
Consulting Engineer: Electronics; Informatics; Photonics.
Remove spaces etc. to reply: n o lindan at net com dot com
psst.. want to buy an f-stop timer? nolindan.com/da/fstop/

JeffM · Jan 1, 2005

great!
James Meyer

With a 50% load that's about what will happen.
If you are in the far north and only need light in the winter
when you also needs lots of heat they'll work just fine.
In Arizona ... probably not a good solution.
Nicholas O. Lindan

Not familiar with deserts?
At night (the only time you should need artificial light),
temperatures drop (summer too).
A tree-hugger would say it's not a good solution for other reasons.

John Stewart · Jan 1, 2005

One other thing I forgot to mention. In Calif, the electric companies
are obligated to give you service that's within certain limits, I
believe it's 105 to 125VAC. I had a problem with a piece of equipment
that would work fine in one bldg but wouldn't work in another bldg, and
it turned out that the AC was too high a voltage. I talked to the
electricians and they said it was because the transformer was delta
instead of wye. In any case they couldn't change it. Later the lab
moved to another bldg so it didn't make any diff.

But seriously, it's something that you should look into. My guess is
that you're out on the end of a high V line with loads that are dragging
it down, and the electric co decided to boost it to give an acceptable
minimum, instead of fising the problem, a poorly regulated circuit. It
could be that your line needs to have some capacitive buildout, or some
other modification, Too bad you can't mnodel the circuit in SPICE and
figure out what's wrong. ;-)

In most systems upstream from the load there is a piece of electrical gear
called a 'line drop compensator'. It simulates the line impedance out to the
load with a set of R's & L's within a subassembly box. Both are adjustable
so that your power company can make allowance for automatic load balancing
over a broad range & a number of different load conditions.

Needless to say that it is not possible to adjust for all the loads but thay
can get pretty close. The error voltage resulting from this gadget controls
automatic switchgear, usually in a 3-phase auto transformer. Sometimes you
will see three separate singlephase transformers on three sucessive poles.

Cheers, John Stewart

Rich Grise · Jan 1, 2005

On Fri, 31 Dec 2004 19:48:26 -0800, Watson A.Name - "Watt Sun, the Dark
Remover" wrote:

"John Woodgate" <jmw@jmwa.demon.contraspam.yuk> wrote in message
news:0fwoxbHBEc1BFwQo@jmwa.demon.co.uk...
I read in sci.electronics.design that Jim Thompson
thegreatone@example.com> wrote (in
phebt0t0702depn17p2vc4nt0c3kip57lg@
4ax.com&gt about 'Constant Voltage Transformer Question', on Fri, 31
Dec
2004:

I was wondering how Constant Voltage Transformers would perform with
lamp loads.

There might be 'start-up' issues, if you have a fitting with a lot of
lamps in it, due to inrush current, but AFAIK CVTs work very well with
resistive loads.

I'm thinking of room-by-room regulation for ceiling fixtures...
since,
15' up, it's tricky with a lamp changer pole :-(

Why not regulate all the lighting circuits with one CVT?

You do know that they are liable to hum, don't you?

More like BUZZZZZZZZZZZZZZZZZZZZZZZZZZZZZ.

All the time.

I worked for a battery charger guy once. He made ferro trannies for
everything, and he potted them. Actually, dipped them in hot varnish, then
baked them out for a day.

They were absolutely silent.

The place kinda smelled like hot varnish, however. Luckily they only did
batch about once a week or so.

But it's cool watching a ferroresonant tranny regulate, especially when
you've got a variac and an AC ammeter. As soon as you apply any voltage at
all, the current goes WAY up. The first time I did it, I kinda panicked
when it was drawing 7 amps on the primary at about 3 VAC in. "It's
regulaging!" he said. He was beaming, probably because he designs them.
Of course, the current went to practically zero at no load and full V.

They were also inherently short-circuit protected. Well, current-limited;
I'm not sure if those are really technically different things.

Cheers!
Rich

John Stewart · Jan 1, 2005

One other thing I forgot to mention. In Calif, the electric companies
are obligated to give you service that's within certain limits, I
believe it's 105 to 125VAC. I had a problem with a piece of equipment
that would work fine in one bldg but wouldn't work in another bldg, and
it turned out that the AC was too high a voltage. I talked to the
electricians and they said it was because the transformer was delta
instead of wye. In any case they couldn't change it. Later the lab
moved to another bldg so it didn't make any diff.

But seriously, it's something that you should look into. My guess is
that you're out on the end of a high V line with loads that are dragging
it down, and the electric co decided to boost it to give an acceptable
minimum, instead of fising the problem, a poorly regulated circuit. It
could be that your line needs to have some capacitive buildout, or some
other modification, Too bad you can't mnodel the circuit in SPICE and
figure out what's wrong. ;-)

In most systems upstream from the load there is a piece of electrical gear
called a 'line drop compensator'. It simulates the line impedance out to the

load with a set of R's & L's within a subassembly box. Both are adjustable
so that your power company can make allowance for automatic load balancing
over a broad range & a number of different load conditions.

Needless to say that it is not possible to adjust for all the loads but they

can get pretty close. The error voltage resulting from this gadget controls
automatic switchgear, usually in a 3-phase auto transformer. Sometimes you
will see three separate singlephase autotransformers on three sucessive
poles.

Cheers, John Stewart

Rich Grise · Jan 1, 2005

On Sat, 01 Jan 2005 12:18:28 -0500, Greg Neff wrote:

On 31 Dec 2004 13:22:03 -0800, Winfield Hill
Jim Thompson wrote...
I was wondering how Constant Voltage Transformers would perform with
lamp loads. I'm thinking of room-by-room regulation for ceiling
fixtures... since, 15' up, it's tricky with a lamp changer pole :-(
Why not change to electronic mini-fluorescent lamps? I'd imagine
they aren't very voltage sensitive and now they're available with
decent color-temperature phosphors, and some can work with dimmers.
Save on electricity, cooling energy, and manpower.

Colour temperature is a problem, especially when mixing lamp types.
We have found that the lamp colour temperature makes a huge difference
in the appearance of wall paint colour, and a mismatch of lighting
makes a room look strange.

In our kitchen we have 4' fluorescent tubes in part of the kitchen,
and a 3-lamp ceiling-mounted fixture in the eating area. We had a
heck of a time finding CFLs with a comparable colour temperature. All
warm-white CFLs are no good. I tried a GE CFL with a 6500K (IIRC)
temperature, but its light output had a very strong and unpleasant
blue component. We ended up using Panasonic "cool white" EFD14E50
lamps (colour temp 5000K). Something with just a touch lower colour
temperature would be ideal.

What about Gro-Lites? Admittedly, they're almost red, but I wonder if
that'd balance out with a cool-white?

Thanks,
Rich

Jim Thompson · Jan 1, 2005

On Sat, 01 Jan 2005 22:36:34 GMT, nico@puntnl.niks (Nico Coesel)
wrote:

Jim Thompson <thegreatone@example.com> wrote:

On 31 Dec 2004 13:22:03 -0800, Winfield Hill
hill_a@t_rowland-dotties-harvard-dot.s-edu> wrote:

Jim Thompson wrote...

I was wondering how Constant Voltage Transformers would perform with
lamp loads. I'm thinking of room-by-room regulation for ceiling
fixtures... since, 15' up, it's tricky with a lamp changer pole :-(

Why not change to electronic mini-fluorescent lamps? I'd imagine
they aren't very voltage sensitive and now they're available with
decent color-temperature phosphors, and some can work with dimmers.
Save on electricity, cooling energy, and manpower.

Do they make those with floodlight shaping?

Yes, but they probably won't fit in the current sockets. I have 2
floodlight shaped lamps which I use to as a light during construction
work. Each of them equals to a 150W bulb.

480)460-2350 | |
| E-mail Address at Website Fax

Richard Crowley · Jan 1, 2005

"Rich Grise" wrote ...

What about Gro-Lites? Admittedly, they're almost red, but I
wonder if that'd balance out with a cool-white?

The lamps made for growing plants don't really care what they
LOOK like, but only that they provide the optimum wavelengths
for photosynthesis (not necessarliy the same wavelengths for
balanced color rendering). I believe some of them make the
green spike even bigger than ordinary floursecent phosphors.

Note that film/video people are moving more and more towards
flourescent lighting and there are several vendors now selling
tubes (both traditional and CFL) at color temps of 3000K, 3200K,
5600K, etc. etc. to match industry-standard incandescent sources.
And many of these lamps have color-rendering index (CRI) > 90%.

Tam/WB2TT · Jan 2, 2005

"Jim Thompson" <thegreatone@example.com> wrote in message
news:82ndt0h0k5p59e1nfn6c6bguq16sg2ac8e@4ax.com...

On Sat, 01 Jan 2005 00:50:05 -0500, **THE-RFI-EMI-GUY**
rhyolite@nettally.com> wrote:

Are they blowing up on turn on or is it when the voltage surges? If its
the former, most likely, why not rig up a dimmer circuit with a shunt
relay with a delay-on timer of say 5 seconds. Then everytime the
circuit is turned on, the lamps will soft start for a few seconds giving
the filaments time to warm up a bit.

The RFI-EMI-GUY

[snip]

Good point. You're right, they almost always fail at turn-on.

...Jim Thompson
--
| James E.Thompson, P.E. | mens |
| Analog Innovations, Inc. | et |
| Analog/Mixed-Signal ASIC's and Discrete Systems | manus |
| Phoenix, Arizona Voice480)460-2350 | |
| E-mail Address at Website Fax480)460-2142 | Brass Rat |
| http://www.analog-innovations.com | 1962 |

I love to cook with wine. Sometimes I even put it in the food.

Jim,

You might want to check your 240V balance. I had a situation here where the
kitchen light got brighter every time the dishwasher turned on.

Tam

JeffM · Jan 2, 2005

Silly thought, but if the load is just incandecents,
why not just use a big thyristor dimmer to (possibly automatically)
trim the RMS value to whatever you happen to like?
Dan Mills

Maybe not silly, but wrong.
A triac-based controller does not control voltage level;
it is a phase controller, varying duty cycle. A triac, once triggered
(assume before 90 degrees and 270 degrees for any brightness at all),
stays triggered until the line voltage crosses zero.
This means that it delivers full peak voltages to the load.
Sorry, Dan. Don't have access to alt.binaries.schematics.electronic.

Jim Thompson · Jan 2, 2005

On Sat, 1 Jan 2005 21:43:40 -0500, "Tam/WB2TT" <t-tammaru@c0mca$t.net>
wrote:

"Jim Thompson" <thegreatone@example.com> wrote in message
news:82ndt0h0k5p59e1nfn6c6bguq16sg2ac8e@4ax.com...
On Sat, 01 Jan 2005 00:50:05 -0500, **THE-RFI-EMI-GUY**
rhyolite@nettally.com> wrote:

Are they blowing up on turn on or is it when the voltage surges? If its
the former, most likely, why not rig up a dimmer circuit with a shunt
relay with a delay-on timer of say 5 seconds. Then everytime the
circuit is turned on, the lamps will soft start for a few seconds giving
the filaments time to warm up a bit.

The RFI-EMI-GUY

[snip]

Good point. You're right, they almost always fail at turn-on.

...Jim Thompson

Jim,

You might want to check your 240V balance. I had a situation here where the
kitchen light got brighter every time the dishwasher turned on.

Tam

480)460-2350 | |
| E-mail Address at Website Fax

Paul Hovnanian P.E. · Jan 2, 2005

Jim Thompson wrote:

A major pain-in-the-ass in Arizona is lightbulb lifetime, particularly
this time of year, where one day will require heat and the next not.

So the AC voltage regulation sucks... often popping up to 130VRMS.

Get the power company to fix their regulation. I don't know about AZ,
but in WA, voltage at the point of service is 120 V +/- 5% for a maximum
voltage of 126 at the meter.

--
Paul Hovnanian mailto

aul@Hovnanian.com
------------------------------------------------------------------
I used to get high on life but lately I've built up a resistance.

Greg Neff · Jan 2, 2005

On Sat, 1 Jan 2005 18:01:49 +0000, John Woodgate
<jmw@jmwa.demon.contraspam.yuk> wrote:

I read in sci.electronics.design that Greg Neff <greg@guesswhichwordgoes
here.com> wrote (in <g3jdt05mst3ultp6fogrn1o4jj777nf5ms@4ax.com&gt about
'Constant Voltage Transformer Question', on Sat, 1 Jan 2005:

All warm-white
CFLs are no good.

I think you probably mean that 'not all are good', rather than 'all are
no good'.

I think I meant 'All warm-white CFLs that I tried had a very
noticeable difference in colour temperature'

(snip)

If I were GE or Philips or whatever, I would develop and promote matched
pairs. I would market cool white CFLs and fluorescent tubes with the
same colour temperature,

AIUI, that's what they think they do.

Hmm. Well then, maybe I am having a CRI problem as well.

(snip)

BTW, I have a question regarding dimming CFLs. One of the effects of
dimming an incandescent lamp is that the colour temperature drops as
the lamp dims. Depending on the application (a romantic dinner for
example) this can be a desired effect. I wonder if this is true for
dimmable CFLs. Has anyone here tried dimmable CFLs, and if so do they
have a pleasant light output when dimmed?

================================

Greg Neff
VP Engineering
*Microsym* Computers Inc.
greg@guesswhichwordgoeshere.com

John Woodgate · Jan 2, 2005

I read in sci.electronics.design that Greg Neff <greg@guesswhichwordgoes
here.com> wrote (in <ko0gt0lp9cks961bmfe64qernhralfgodu@4ax.com&gt

about
'Constant Voltage Transformer Question', on Sun, 2 Jan 2005:

BTW, I have a question regarding dimming CFLs. One of the effects of
dimming an incandescent lamp is that the colour temperature drops as the
lamp dims. Depending on the application (a romantic dinner for example)
this can be a desired effect. I wonder if this is true for dimmable
CFLs. Has anyone here tried dimmable CFLs, and if so do they have a
pleasant light output when dimmed?

The light comes from the phosphor coating and changes colour very little
with excitation level.

You might have a patent there; a phosphor formulation could be devised
to produce the effect you mention. You'd sell a jillion. (;-)
--
Regards, John Woodgate, OOO - Own Opinions Only.
The good news is that nothing is compulsory.
The bad news is that everything is prohibited.
http://www.jmwa.demon.co.uk Also see http://www.isce.org.uk

Watson A.Name - \"Watt Su · Jan 2, 2005

"Tam/WB2TT" <t-tammaru@c0mca$t.net> wrote in message
news:XJydnbz1-tFEwkrcRVn-jQ@comcast.com...

"Jim Thompson" <thegreatone@example.com> wrote in message
news:82ndt0h0k5p59e1nfn6c6bguq16sg2ac8e@4ax.com...
On Sat, 01 Jan 2005 00:50:05 -0500, **THE-RFI-EMI-GUY**
rhyolite@nettally.com> wrote:

Are they blowing up on turn on or is it when the voltage surges? If
its
the former, most likely, why not rig up a dimmer circuit with a
shunt
relay with a delay-on timer of say 5 seconds. Then everytime the
circuit is turned on, the lamps will soft start for a few seconds
giving
the filaments time to warm up a bit.

The RFI-EMI-GUY

[snip]

Good point. You're right, they almost always fail at turn-on.

...Jim Thompson
--

Jim,

You might want to check your 240V balance. I had a situation here
where the
kitchen light got brighter every time the dishwasher turned on.

Tam

At work I've found this happens with three phase, and I've seen the
neutral wire carrying substantial current, especially when I measure the
current near areas where there is one or more copiers. They seem to
have a very high current draw at times, when the fuser comes on. I've
seen several volts diff between the neutral and ground. Check to see if
you nave a situation where the neutral and ground are not close to the
same voltage. Run appliances to see if that makes a diff. And if you
find that there is, it can be fixed with some rearrangement of the loads
on the breaker panel.

Back in the '70s a friend got a microwave oven, and I noticed that his
kitchen lights would dim and brighten when the microwave was on. And I
also noticed that at half heat settings, the lights would dim and
brighten at about ten second intervals, which led me to the conclusion
that all the microwave was doing was switching the magnetron on and off,
and not 'dimming' it on a per cycle basis.

Jim Thompson · Jan 2, 2005

On Sun, 2 Jan 2005 08:18:14 -0800, "Watson A.Name - \"Watt Sun, the
Dark Remover\"" <NOSPAM@dslextreme.com> wrote:

[snip]

Back in the '70s a friend got a microwave oven, and I noticed that his
kitchen lights would dim and brighten when the microwave was on. And I
also noticed that at half heat settings, the lights would dim and
brighten at about ten second intervals, which led me to the conclusion
that all the microwave was doing was switching the magnetron on and off,
and not 'dimming' it on a per cycle basis.

480)460-2350 | |
| E-mail Address at Website Fax

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