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Twin Tube HF fluorescent lighting for the workshop

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Adam Harris12/10/2018 16:51:50
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Hugh actually sorry I had been wiring in parallel rather than series - I had been wiring L to L to L , N to N to N etc. (Series would be Plug L to Light#1 L, then Light#1 N to Light#2 L , then Light #2 N to Plug N). Anyway, since I have been wiring in parallel, the RCD must have tripped because of excessive startup surge with all startups simultaneous, OR some mysterious frequency interference between units??

SillyOldDuffer12/10/2018 17:31:48
3512 forum posts
687 photos

Posted by Andrew Tinsley on 12/10/2018 14:47:01:

...Yes I calibrate my tachometer with a fluorescent tube. ... The eye can't respond to 50 or 100 Hz unless you are a very odd man out, so this isn't the flicker you see with an old fluorescent tube.

...

Andrew

The Wikipedia article on 'Flicker Fusion Threshold' is worth a look. New to me is the statement under 'Lighting':

"Fluorescent lamps using conventional magnetic ballasts flicker at twice the supply frequency. Electronic ballasts do not produce light flicker since the phosphor persistence is longer than a half cycle of the higher operation frequency of 20 kHz. The 100–120 Hz flicker produced by magnetic ballasts is associated with headaches and eyestrain.[12] Individuals with high critical flicker fusion threshold are particularly affected by light from fluorescent fixtures that have magnetic ballasts..."

This may explain why different people have different experiences. Flicker is much more likely if you have a high fusion threshold AND ballast fluorescent tubes.

Also, it seems that electronic ballasts don't work at 100Hz, and that the HF lamps are even higher frequency.

I feel the need to wire a phototransistor up to my oscilloscope to see what's coming off the various lamps I own. Watch this space...

Dave

Alan Vos12/10/2018 18:14:50
101 forum posts
6 photos
Posted by Adam Harris on 11/10/2018 21:22:06:

Is there something to be done to cure this problem or should I try to return them?

If your problem is still unresolved come Monday, I will ask at work. They know most things about tubes, control gear, and the behaviour of circuit breakers.

HughE12/10/2018 18:26:37
94 forum posts

Hi Adam,

Glad to see you have sorted it. I would think that during startup they have a small amount of leakage when added causes your RCD to trip. You triggered my curiosity i will do some research on these lights as I am about add lighting to my garage. In the workshop I have used LEDs as they came free no flicker that I have noticed.

Hugh

John Haine12/10/2018 18:29:51
2191 forum posts
126 photos

Adam, is the earth connected to any of the lights? If it isn't the only way there can be an imbalance between L and N is via an earth fault in your wiring. If the lights do have an earth then sometimes a filtering capacitor can create enough of an imbalance to trip an rcd. So if there isn't an earth check your wiring carefully as it might be dangerous.

Adam Harris12/10/2018 19:45:52
295 forum posts
6 photos

Hi John, yes all lights connected to L,N and E. I am going to connect each of the 5 to their own on/off switch and will revert with the result for those interested. Makes sense to do that anyway I suppose as it means I don't have to waste energy on having all twin lights on at the same time. Furthermore they are also VERY bright and really too bright for all 5 on at the same time ( but correct level of brightness per machine/work area over which they are suspended).

Andrew Tinsley12/10/2018 19:48:37
820 forum posts

HF ballasts operate in the kilohertz regions. They are usually a multivibrator circuit. This means that the resulting hash can go up into the medium and even VHF wavebands. This is why I don't like them. I can't listen to my radio because of the interference.

Andrew

Muzzer12/10/2018 20:20:53
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2904 forum posts
448 photos

If your HF ballasts screw up your radio it suggests you should have bought them from a more reputable outlet. It's illegal to sell stuff that doesn't meet the EMC requirements (look at EN55011). Are you using Chinesium crap?

You will also note that despite what you say, the colour temperature is usually specified for fluorescent tubes.

And as mentioned on various previous occasions, LED lights are generally about the same as fluorescent lights in terms of efficiency.

The of the key benefits of HF ballasts is that they turn on almost instantaneously and can coax a little more life out of the tubes before they give up the ghost. As a tube gets older, the voltage rises until it can't be kept running.

For me, one key benefit of LED lights in the workshop is the lack of glass tubes above head height. Belting one of those or dropping one when changing it on top of a ladder could be pretty messy.

Some HF ballasts (and many LED drivers) have very little inherent energy storage, so although it's true that they switch at several kHz, they often have a significant 100Hz component.

Murray

HughE12/10/2018 21:25:13
94 forum posts

I agree with Muzzer. If the correct spec'ed device is used then there should be no interference to other electronic equipment. Note that there are two version one for commercial and one for residential use. The commercial can give problems in a residential environment as the EMI protection is not as good. EMI is both conducted and radiated so if you have a problem the you to check which is causing the problem. Reading the tech advice from GE suggests you should keep electronic equipment as far away as possible, which may not be possible in a home workshop.

Also the earthing is important. If you have as high impedance earth then the light fitting could be acting as an aerial, if metal.

Hugh

Edited By HughE on 12/10/2018 21:26:35

Edited By HughE on 12/10/2018 21:27:04

Samsaranda13/10/2018 12:54:22
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523 forum posts
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Muzzer, your comment about “Chinesium Crap” is a bit harsh as nowadays it is almost impossible to buy equipment that is either not a Chinese product or contains some of its basic elements that have been produced in the orient. Can you name any fluorescent light units that do not contain anything produced in the Far East?

Dave W

Andrew Tinsley13/10/2018 13:18:05
820 forum posts

hello Dave,

yes I should have said 100hz flicker for magnetic ballasts. This frequency is way above what the average human eye can see. I don't have information to hand about the subliminal effects, so can't comment.

I have examined HF ballasts which operate from as low as 4kHz to near 50 kHz. The basic problem is that the circuits are mainly multivibrator. This leads to a sharp edge on the cut off which produce harmonic oscillations into the mHz region, thus producing copious interference in the RF spectrum. Few HF ballasts have sufficient RF suppression. As Muzzer said, they are cheap Chinesium crap, as opposed to the expensive Chinese stuff manufactured for reputable European majors

Interesting that you sited the GE blurb. I had a hand in writing it!

Andrew.

Michael Gilligan13/10/2018 13:40:59
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12062 forum posts
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Posted by Andrew Tinsley on 13/10/2018 13:18:05:

hello Dave,

yes I should have said 100hz flicker for magnetic ballasts. This frequency is way above what the average human eye can see. I don't have information to hand about the subliminal effects, so can't comment.

[ ... ]

.

The ergonomic problem [as distinct from the strobe-effect on rotating machinery] is not so much related to what we can see, but to how the eye/brain reacts to off-axis stimulation.

Common 'good practice' in large offices was to install fluorescent fittings alternately 'end for end' to smooth-out the intensity fluctuations. ... Another solution [useful when appropriate] is to use 'circular fluorescents' which, of course, put the two ends of the same tube nearly coincident.

MichaelG.

Andrew Tinsley13/10/2018 14:05:45
820 forum posts

Hello Michael,

I can't see what point you are trying to make. The distribution of fluorescent lights in offices are indeed as you describe. This is simply to even out illumination and attempt to produce shadow free lighting. It has nothing to do with flicker. Are you saying that such a layout minimises any subliminal effects?

I would be interested in further information if you are claiming that it reduces subliminal effects. I am always willing to learn. I have never come across such information, but that only means I have probably missed it.

Andrew.

Michael Gilligan13/10/2018 14:34:05
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12062 forum posts
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Posted by Andrew Tinsley on 13/10/2018 14:05:45:

Are you saying that such a layout minimises any subliminal effects?

.

In a word ... Yes

The subliminal effects are reduced, simply because the ON end of one tube is adjacent to the OFF end of the other tube so the 'microclimate' [for want of a better term] is illuminated by the average of the two.

MichaelG.

.

Reference source, for the present, is only my personal recollection from BSc Ergonomics.

... but I will try to locate something more authoritative over the next few days.

.

Edit: Hopefully, Dave [S.O.D.] will find two photocells, and a dual trace 'scope ... to demonstrate that the two ends of the tube flicker in anti-phase.

Edited By Michael Gilligan on 13/10/2018 14:49:43

Andrew Tinsley13/10/2018 16:06:57
820 forum posts

Thanks for that Michael,

You may well have something. But I am still very dubious. The 100Hz phases for two lamps are always in phase, they have to be because the same 50Hz voltage is driving both of them, For what you are claiming, the voltage needs to be 90 degrees out of phase, between the two lamps.

Maybe I am missing something? I am not trying to cause dissension, just curious. There is too much arguing on forums, but not too bad here!

Andrew.

Neil Wyatt13/10/2018 17:01:09
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Posted by Andrew Tinsley on 13/10/2018 16:06:57:

Thanks for that Michael,

You may well have something. But I am still very dubious. The 100Hz phases for two lamps are always in phase, they have to be because the same 50Hz voltage is driving both of them, For what you are claiming, the voltage needs to be 90 degrees out of phase, between the two lamps.

Maybe I am missing something? I am not trying to cause dissension, just curious. There is too much arguing on forums, but not too bad here!

Andrew.

I think Michael is suggesting that the lamp is brighter at one end than the other depending on the direction of electron flow. By placing tube L:N then the flow in adjacent tubes will be in opposite directions, 180 degrees out of phase.

I looked to see if there were any slow-motion videos but they aren't slow enough.

Michael Gilligan13/10/2018 17:35:08
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Posted by Andrew Tinsley on 13/10/2018 16:06:57:

Thanks for that Michael,

You may well have something. But I am still very dubious. The 100Hz phases for two lamps are always in phase, they have to be because the same 50Hz voltage is driving both of them ...

.

Andrew,

I think what you missed might be that I carefully said that the fittings were swapped end-for-end.

... this 'mechanically' introduces a phase shift.

Like Neil, I have thus far failed to find video or similar evidence to support my case. sad

MichaelG.

Andrew Tinsley13/10/2018 17:36:01
820 forum posts

Hello Neil,

Now I am really confused! As soon as current flows (electrons one way and ions the other!). The lamp emits light from end to end. The idea that one end of the tube is brighter than the other is incorrect. So I don't think that this is Michael's point (?). I understood him to infer that the 100Hz flicker would be out of phase at adjacent ends of tubes in a row. Thus cancelling out the 100Hz flicker. The adjacent ends of the tubes are in fact in phase with each other so I cannot understand how this would reduce the 100Hz flicker.

As I said before, I could well be missing the point.

Andrew.

Frances IoM13/10/2018 17:39:01
539 forum posts
22 photos
I suspect in a large office the lamps must be fed from all three phases to even out the load which might even out flickers.

Many years ago I wrote the software to allow control of each individual light fitting by dialling a specific number from a specific phone that had been associated with that fitting - saved a lot of money (peak rate electricity to take away heat of lamps) + office occupants were very happy as I suspect the susceptibility to seeing flicker is more common than suspected

Edited By Frances IoM on 13/10/2018 17:39:41

Michael Gilligan13/10/2018 17:49:56
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12062 forum posts
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I don't think this either supports or refutes my proposition, but it's interesting: **LINK**

http://www.giangrandi.ch/electronics/fluorescenttubes/fluorescenttubes.shtml

MichaelG.

.

More good stuff here: http://edisontechcenter.org/Fluorescent.html

... but still no simple confirmation indecision

Edited By Michael Gilligan on 13/10/2018 18:16:42

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