Constant Voltage Transformer Question

4ax.com>) about 'Constant Voltage Transformer Question', on Fri, 31 Dec

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All the time.

Reply to
Watson A.Name - "Watt Sun, th
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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. ;-)

Reply to
Watson A.Name - "Watt Sun, th

I've used 3KVA Sola CVTs and I believe they made 5 KVAs. Just how big is your load?

Reply to
James T. White

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

Jim Thomps>A major pain-in-the-ass in Arizona is lightbulb lifetime, particularly

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Joe Leikhim K4SAT
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**THE-RFI-EMI-GUY**

Voltage in my house in Massachusetts is 127 most of the time. I think it is that high as there are a lot of teardowns being replaced with MacMansions. These huge houses require a lot of power and it probably drops considerably just from the pole to the house. My little house just uses on an average of 350KWH/mo. The biggest drain is the rare use of the electric oven.

When I got my MacPlus many moons ago, I also bought a TrippLite Power Regulator/Conditioner. My Plus is still a go although I've heard that many of them lost their PSs due to surges and sags. I could hear the relays clicking in the TrippLite my wife would turn on the dryer. Now it just sits gathering dust.

You want it, you got it, for the price of shipping and handling ;-)

You want specs, I'll send them to you if your're interested.

Al

Reply to
Al

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:

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

Greg Neff VP Engineering

*Microsym* Computers Inc. snipped-for-privacy@guesswhichwordgoeshere.com
Reply to
Greg Neff

[snip]

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

...Jim Thompson

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|  James E.Thompson, P.E.                           |    mens     |
|  Analog Innovations, Inc.                         |     et      |
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Reply to
Jim Thompson

Reply to
Bennett Price

I read in sci.electronics.design that Greg Neff wrote (in ) about 'Constant Voltage Transformer Question', on Sat, 1 Jan 2005:

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

6500 K is US daylight and is indeed too blue for use in the home. Ideal for colour-matching and some benchwork.
5000 K is British daylight, and is beyond reproach. (;-)

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.

AIUI, that's what they think they do.

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.

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Reply to
John Woodgate

"James Meyer" wrote

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.

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.

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Nicholas O. Lindan, Cleveland, Ohio
Consulting Engineer:  Electronics; Informatics; Photonics.
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Reply to
Nicholas O. Lindan

Look in the Newark or Allied catalogs/web sites for Line Conditioners or Power Conditioners. These are automatic switched tap transformers. Or for more entertainment value, they may still make servo driven variacs. Staco. SL Waber, Tripplite, Stabiline, ...

Mark Zenier snipped-for-privacy@eskimo.com Washington State resident

Reply to
Mark Zenier

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.

Reply to
JeffM

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

Reply to
John Stewart

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

Reply to
Rich Grise

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

Reply to
John Stewart

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

Thanks, Rich

Reply to
Rich Grise
[snip]

then

The ones we have are true Solas, and the transformer itself is not so much the reason it buzzes. The whole chassis vibrates, probably because it has to be made out of steel, because the beast weighs close to a hundred pounds (45kg).

[snip]

Reply to
Watson A.Name - "Watt Sun, th

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.

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Reply to
Nico Coesel

I have a two-head work light on a tripod... 2x 500W halogens ;-)

...Jim Thompson

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|  James E.Thompson, P.E.                           |    mens     |
|  Analog Innovations, Inc.                         |     et      |
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Reply to
Jim Thompson

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%.
Reply to
Richard Crowley

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