[Keeper of the Keys]

I don't know about Britain but it's expected that SCR type dimmers will be forbidden or induce a penalty extra charge from Electricity providers in Europe (due to the 'pollution' they cause on the net) within the next 10-20 years so it would seem that if you want to do another lasting install you might be better of with a (more expensive) sine wave system.

[church]

Keeper of the Keys, on 5 Jun 2009, 5:13 AM, said:

I don't know about Britain but it's expected that SCR type dimmers will be forbidden or induce a penalty extra charge from Electricity providers in Europe (due to the 'pollution' they cause on the net) within the next 10-20 years so it would seem that if you want to do another lasting install you might be better of with a (more expensive) sine wave system.

if things keep going like this we will be reduced to living in caves, eating raw meets nuts and roots again.

[Keeper of the Keys]

church, on 5 Jun 2009, 2:46 PM, said:

Keeper of the Keys, on 5 Jun 2009, 5:13 AM, said:

I don't know about Britain but it's expected that SCR type dimmers will be forbidden or induce a penalty extra charge from Electricity providers in Europe (due to the 'pollution' they cause on the net) within the next 10-20 years so it would seem that if you want to do another lasting install you might be better of with a (more expensive) sine wave system.

if things keep going like this we will be reduced to living in caves, eating raw meets nuts and roots again.

It's more like they are preparing to force the caveman out of the cave and into a house, as sine wave dimmers are "the next step" in dimming, if they wanted to take a step back we'd go to resistance dimmers.

The reasoning behind these expected changes are fairly simple really, SCR dimmers cause harmonics on the returning line, these harmonics make the generators have to work harder or fool the control circuitry making them miss a beat or speed up.
The energy providers obviously don't like that as it can cause damage and makes generating the same amount of energy more expensive, add higher fuel prices to that and you'll understand why energy companies will want to start to charge SCR users for the extra cost or legislation is going to be introduced forbidding SCR dimmers.

Other than that sine wave dimmers are nicer as they also eliminate the interference to sound equipment.

[niclights]

Keeper of the Keys, on 5 Jun 2009, 2:30 PM, said:

Other than that sine wave dimmers are nicer as they also eliminate the interference to sound equipment.

It is my understanding that there are significant problems in getting fast rise times with sine-wave. So it's not necessarily a straightforward matter.

[Keeper of the Keys]

I spoke to a guy who's been using them for the past 4-5 years, he said that the factory default curves are on the slow side but that after changing the curve it was fine for them. (This is a major theater that has shows from all of the spectrum)

[dmxtothemax]

rooftop, on 4 Jun 2009, 6:10 AM, said:

I am sure the H&S/electrical bods know what's best

You would assume so, but I have found them to be remarably ignorant of technical issues, DONT ASSUME THEY KNOW ABOUT TECHNICAL ISSUES, always research for your self, I think it is not likely that the electros in dimmer racks are using PCBs, they are only in larger type, high power type electros
that sit across the mains for long periods. ie- power factor correction.

[rooftop]

You miss my point: I am sure they know what's best for us.

Anyway it's been two weeks and still no more communication from them (there's a surprise) so I don't know what is happening. I suspect they've probably done a rough survey of all old electrical equipment in the authority and realised it will cost them hundreds of thousands (if not into millions) to replace all of it (based on the premise that anything built before '86 could contain PCBs).

[musht]

Keeper of the Keys, on 5 Jun 2009, 10:13 AM, said:

I don't know about Britain but it's expected that SCR type dimmers will be forbidden or induce a penalty extra charge from Electricity providers in Europe (due to the 'pollution' they cause on the net) within the next 10-20 years so it would seem that if you want to do another lasting install you might be better of with a (more expensive) sine wave system.

Sine wave dimming isn`t exempt from messing with power factor, despite what some enthusaistic marketing may make you think, for a much larger installed base of high power SCR controllers than lighting dimmers, motor drives in every factory, warehouse and office block in the country, HVAC , lifts ,conveyors etc

http://en.wikipedia....otor_controller

VFDs bit ahead of sine wave dimming but not completely problem free

http://en.wikipedia.org/wiki/Variable-freq..._line_harmonics

Guess someone looked at cost of proper disposal of all the PCB ridden equipment.....

[Tomo]

musht, on 13 Jun 2009, 2:18 PM, said:

VFDs bit ahead of sine wave dimming but not completely problem free

I think you may have missed the point. VFDs are completely different to sine-wave dimming - they don't really share many notable characteristics.
VFDs take an incoming AC power supply, and produce an output sinewave at variable frequency to control the motor. This means that there will be some very interesting harmonics from the transformation.

Sinewave dimmers take an incoming AC power supply, and produce an output sinewave at variable amplitude to control the load.

A sinewave dimmer is essentially a solid-state variable-turns-ratio transformer - from the point of view of the supply, a good sinewave dimmer is almost identical to a transformer.

This post has been edited by Tomo: 13 June 2009 - 04:42 PM

[bjkered]

rooftop, on 3 Jun 2009, 9:10 PM, said:

I am sure the H&S/electrical bods know what's best

I hope this is a sarcastic comment as I have met many an H/S - Electrical bod who doesnt. ( been electrocuted a few times by a "qualified electrican"

[musht]

Tomo, on 13 Jun 2009, 3:32 PM, said:

musht, on 13 Jun 2009, 2:18 PM, said:

VFDs bit ahead of sine wave dimming but not completely problem free

I think you may have missed the point. VFDs are completely different to sine-wave dimming - they don't actually share any notable characteristics.
VFDs take an incoming AC power supply, and produce an output sinewave at variable frequency to control the motor. This means that there will be some very interesting harmonics from the transformation.

Sinewave dimmers take an incoming AC power supply, and produce an output sinewave at variable amplitude to control the load.

A sinewave dimmer is essentially a solid-state variable-turns-ratio transformer - from the point of view of the supply, a good sinewave dimmer is identical to a transformer.

You spotted my basic error ooops, of course a Variable Frequency Drive is differnt to variable Amplitude, should have widened the scope to mention inverter drives that include VFDs and variable amplitude systems.

As far as am aware all of them including sine wave dimming , rectify the incoming A.C. mains and reconstruct output from D.C. , don`t think it presents itself as straightforward passive inductor to the supply.

Was it Barbican that had an early install of sine wave dimming pulled out beacsue of uneven dimming, very early install early 90`s?

[musht]

Cannae go back and edit it , but after further reading, not claiming to be an expert on dimming or motor drives , see what you mean, decent sine wave dimmer should look just like a.n. ordinary load to supply:

http://www.etdimming...ads/87-0539.pdf

Know there pushing IGBT reverse phase dimming , but still shows power line noise is not a problem with sine wave, don`t understand why R.F noise is lsited as problem with sine wave?

[Dmills]

musht, on 13 Jun 2009, 11:45 PM, said:

Know there pushing IGBT reverse phase dimming , but still shows power line noise is not a problem with sine wave, don`t understand why R.F noise is lsited as problem with sine wave?

A sine wave dimmer looks a lot like a slightly weird switch mode power supply (Specifically it looks like a SMPSU PFC circuit (kind of)), and as it uses a high frequency chopper, it can generate RFI if not well filtered (This is the switching hash at 10 - 100Khz fundamental, not the line harmonics generated by any type of phase control).

IGBT Reverse phase control dimming is NOT the same thing.

[dbuckley]

Tomo, on 14 Jun 2009, 3:32 AM, said:

VFDs take an incoming AC power supply, and produce an output sinewave at variable frequency to control the motor.

The only scope display I've seen was very far from a sine wave. Ok, thats a sample size of one, so may be very non-representative, but for that sample, it was nowt like a sine wave. In my support your honour I point out that you are recommended to have special cables betwixt the VFD and the motor, which if the VFD were chucking out nice waveforms that would not be required...

[Tomo]

dbuckley, on 13 Jun 2009, 11:08 PM, said:

Tomo, on 14 Jun 2009, 3:32 AM, said:

VFDs take an incoming AC power supply, and produce an output sinewave at variable frequency to control the motor.

The only scope display I've seen was very far from a sine wave. Ok, thats a sample size of one, so may be very non-representative, but for that sample, it was nowt like a sine wave. In my support your honour I point out that you are recommended to have special cables betwixt the VFD and the motor, which if the VFD were chucking out nice waveforms that would not be required...

Well, it's supposed to approximate a sinewave, although I suspect none of them have any internal inductance to clean up the PWM pulses. After all, the motor is a dirty great big choke!

Incidentally, the Entertainment Technology link is very simplistic.
There are a lot of issues with IGBT 'reverse phase' dimming they've missed out - for a start, it does not 'eliminate' triplen harmonics.
It reduces them to around 600uS fall-time - which can actually be done for the rise-time in SCR dimming with a really big choke. (Weighs rather a lot though)
(You can't go much slower because the 'fall time' is while the IGBT is in the linear region, and dissipating a LOT of power. You don't want to do that for very long.)

Sinewave dimming on the other hand genuinely does give you much less than 1% total harmonic distortion, if you choose one that has a choke inside.

This is all very much though!

This post has been edited by Tomo: 14 June 2009 - 04:32 PM