Fluorescent light

[Johnny B Good]

Which is the very reason why using 10 to 20 KHz ac current instead of 50 or 60Hz gives something like a 10% or so boost in lamp efficacy. IIRC, large department stores were one of the early adopters of using a dedicated high frequency lighting supply feed to modified luminaries.

They didn't go to the extreme of 10KHz but, afaicr, chose a common 3KHz supply generated by a Thyristor based frequency converter[1] which allowed the use of lighter more efficient inductive ballast chokes in each luminary. Nevertheless, the higher frequency supply did improve the efficacy of the tubes, reducing running costs sufficiently to justify the capital investment in the system.

[1] The Thyristor based frequency conversion technology used by such department stores required the use of a three phase supply afaicr. I suppose the less than ideal choice of 3KHz was a compromise over conversion and distribution losses that would have otherwise been incurred with a 10KHz supply.

[Andrew Gabriel]

Probably the RFI too. The full boost in efficiency is normally quoted as occuring at 5kHz. Note that in the EU, you won't get any more light from an electronic ballast because EU rules now require them to all underrun the tubes by the same amount for energy efficiency reasons. If your ballast is marked EEI=AA1 or AA2, then it underruns its tubes, and if it isn't marked with one of these efficiency ratings, it's illegal to import or manufacture in the EU.

[Harry Bloomfield]

[e-mail] a écrit :

I have a couple of bench lights on arms, which use manual switching. I tend to be impatient with both - not allowing them enough pre-heat time, before trying to get them to strike, so I have to repeat.

[Fredxxx]

Do you have any cite for that. When I looked up AA1 and AA2, the only meaningful document I found was:

that suggest AA1 and AA2 refer to dimensions.

Where is this regulation of underrunning the tubes?

[Harry Bloomfield]

Fredxxx a écrit :

If it helps, I have heard of it before.

[Timothy Murphy]

Why do you feel fluorescent lights are superior to LED fittings?

I've replaced our kitchen under-cupboard fluorescent lights with IKEA LED lights (OMLOPP), which seem to me better in every way: they take less power, they are low voltage (24v) and so safer, they are lighter and easier to install. They seem to me (but I am no expert) slightly warmer in colour than the "warm white" fluorescent tubes we had before.

One of the reasons I changed was that I was told by my local store that they were no longer stocking warm white tubes as "fluorescent tubes were obsolete". Is that complete nonsense?

[Dave Plowman (News)]

What concerns me is the quality of the light from these super efficient LEDs. Or any LED, come to that. It may not matter much for just general illumination, but may well where quality florries would be used, where the ability to match colours etc matters.

In general at home I'm more concerned with having pleasant and convenient lighting than saving a few pennies.

The difficulty in dimming many LEDs also rules them out for me.

[Dave Plowman (News)]

I did say like for like. Lumens per watt tells you nothing about the light quality.

[Dave Plowman (News)]

How a light source appears, colour wise, has little to do with how it performs across the spectrum. Of course I do realise this simply doesn't matter to many.

Yes.

[dennis]

You do know that the majority of cheap white LEDs are fluorescent? They use similar phosphors to the tubes.

The RGB LED based ones tend to have colour fringes around shadow edges as well as being dimable and programmable colours.

[Dave Plowman (News)]

'Phosphors' cover a vast range. Since decent florries use very different phosphors from 'ordinary' ones, I'd guess the same applies. And a phosphor which gives the very best results colour wise will almost certainly not give the best 'efficiency'. And pretty well every new lighting source is sold on the basis of efficiency, not performance. In that respect, all downhill after halogen. ;-)

And don't necessarily give good colour rendering either. Having three distinct colour sources without clever optics will result in fringing.

I don't want programmable colours. Just reasonably continuous colour spectrum and the ability to dim them.

[Fredxxx]

Well, yes, but I was wondering why, when you're intentionally running the cathodes at a lower than optimum temperature.

[F Murtz]

Not much, I put two in the bathroom about a year ago,tested output of fluoro v led with a lux metre(both nearly the same)have to wait a couple more years for useful idea.

[harry]

Better still you can get LED replacement tubes. Ballast and other sterter gear is chucked away.

[Johnny B Good]

I note that it has a 90L/W efficiency and the need to slightly modify the wiring in the luminary (a common requirement for many such 'drop in' tube replacements).

At ten or more times the price of a regular tube, I do wonder at the point of such an exercise right now. In my view, it makes more sense to wait for the 200 to 300 lumens per watt LEDs to finally materialise in the stores sometime in the next 12 months or so according the the promises being made by the likes of Cree and Philips Lighting Technology. One more replacement fluorescent tube aught see you through till then.

[qinminyu1]

? 2015?6?26???? UTC

+8??3:40:59?Corporal Jones??? ?

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