Topic: Fluorescent lighting (Read 13140 times)

Southern Sailor · « **on:** September 22, 2012, 05:51:01 pm »

I am upgrading the lighting in my workshop and have heard a negative report about using fluorescent lighting. It has to do with the flickering in this type of light causing problems with moving objects, specifically a rotating chuck in a lathe, for instance. Can anyone comment on this, or give advice on the best lighting to use? Thanks. Brian

Neil · « **Reply #1 on:** September 22, 2012, 05:54:11 pm »

I've got three 5' strips in my workshop and a Myford laithe........never had any problems.
neil.

essex2visuvesi · « **Reply #2 on:** September 22, 2012, 06:07:37 pm »

its something to do with the speed of the chuck and the cycle rate (50Hz) of the flourescent tube

at a certain point the lathe speed and the frequency of the light converge causing the chuck to look stationary

Southern Sailor · « **Reply #3 on:** September 22, 2012, 06:13:30 pm »

Thanks for comments. essex2 that is what I heard, but it seems there are enough fluorescent-lit workshops out there without a problem to make it not worth worrying about. So, fluorescent tubes it is. regards Brian

Jerry C · « **Reply #4 on:** September 22, 2012, 06:21:20 pm »

Danger due to stroboscopic effect. Always understood workshops with rotating or vibrating machinery must have an additional incandessant light source if using strip lights. Recently had probs with violently vibrating pipe on air con compressor only visible with torch shining on it. Spooky!
Jerry.

tt1 · « **Reply #5 on:** September 22, 2012, 06:22:43 pm »

The electronic ballasted modern fittings do not usually flicker, fluorescent lights emit a 'pulsing signal' but not noticeable to the human eye, many supermarkets use this to their advantage with an electronic ticket bar system that can update prices and data of merchandise in real time, to numerous stores, with "the push of a button" from a remote centre.

Fluorescent lighting was the norm in workshops for many years, and the flickering was due to duff capacitors ballasts or the tubes on the blink - literally

irishcarguy · « **Reply #6 on:** September 22, 2012, 06:30:04 pm »

Actually it is a problem & can cause very dangerous situations around any rotating machinery. You should always in addition to fluorescent light also have an incandescent light as well where you have rotating machinery. As you will see most machines have their own incandescent light fitted, especially grinders & lathes. Fluorescent lighting causes a strobe effect & will make under certain circumstances spinning machinery to actually look stationary, very dangerous. As an aside in hockey rinks they nearly always have an incandescent light above the the net to eliminate the strobe effect on the puck so that it does not create an optical illusion on the goalkeeper. Mick B.

Howard · « **Reply #7 on:** September 22, 2012, 06:54:35 pm »

As far as I understand it at 50hz the tubes flicker at 50 times a second and the human eye only picks this up if things flicker less then 25 times a second or am I talking rubbish.
Regards Howard.

boatmadman · « **Reply #8 on:** September 22, 2012, 07:15:31 pm »

If you are going to install flouro lighting, make sure you get them with high frequency electronic ballast. There are a few advantages:
1. The electronics reduce flicker that you see with magnetic ballast/
2. Quicker start up.
3. Cheaper to run.

The downside is they cost more upfront.

I have 2 5ft flouros in my garage/workshop. I did a rough and ready load check and found they use 300w of power to light two 58w t8 tube. These are magnetic ballast units.

I then bought one hf electronic ballast to replace one magnetic ballast, did the check again and the load was down 100w.

conclusion: Magnetic ballasts waste your money!

It make no financial sense to spend £13 on a new ballast unit, as the return on cost is over a long time - depending on how much you use the light, but, as a new installation its a no brainer.

Ian

Jerry C · « **Reply #9 on:** September 22, 2012, 07:21:17 pm »

It's because you can't pick it up that makes it a problem. In fact you're in the dark most of the time. If the rotating part is in the same place every time it's light it will appear stopped. If the light and the AC motor are on the same source and no daylight or incandescent light is available then it can occur. Using two phases, one for lights and one for motor also won't stop it because the frequency is exactly the same.
Jerry.

Southern Sailor · « **Reply #10 on:** September 22, 2012, 08:14:10 pm »

Wow guys, what a response. Very valuable advice, Thanks so much. Electronic balast it is then. Brian

Tug-Kenny RIP · « **Reply #11 on:** September 22, 2012, 09:21:10 pm »

I have three 58 watt fluorescent lights running under the assumption that they use around 174 watts of electricity.

Would you say that this is wrong and that they might be using more wattage than indicated please. ??

boatmadman · « **Reply #12 on:** September 22, 2012, 09:30:00 pm »

Kenny,

It all depends on the type of ballast fitted. If they have the little screw in starters you have magnetic ballast, if not, you have electronic ballast.

From my checks 3 magnetic ballasted lights like yours may be using up to 450watts. Its the energising of the magnetic ballast and capacitors that increase the load used.

You should also be using T5 or T8 tubes to minimise running costs. These are smaller diameter than the older type and give out just as much light.

Before you dash out and buy 3 electronic ballasts costing around £36 plus delivery, you might want to do a ball park calculation on how long it will take to recover the purchase cost compared to the cost of the extra power you are using, this of course depends on how much you use the lights.

On the other hand, it makes you feel good to cut your power consumption.

Ian

Tug-Kenny RIP · « **Reply #13 on:** September 22, 2012, 09:34:20 pm »

Just as I feared. They are the thin tube type but as they use that much lecky, I shall be reverting to ordinary modern lamps to cut costs from now.

RAAArtyGunner · « **Reply #14 on:** September 22, 2012, 10:58:04 pm »

Quote from: essex2visuvesi on September 22, 2012, 06:07:37 pm

its something to do with the speed of the chuck and the cycle rate (50Hz) of the fluorescent tube

at a certain point the lathe speed and the frequency of the light converge causing the chuck to look stationary

In oz we also use 240V 50Hz electrical supply.

As an aside have an old high quality, record playing turn table.
The set up instrcutions require a fluorecent light source to help adjust the turntable speed motor until the lines on the speed strobe disc appear stationary.

So yes, a problem with moving parts as at speed equal to 50Hz, that part will appear stationary to the naked eye.

Am also in accord with all commentary for specific local non fluorescent lighting to all moving machinery.

derekwarner · « **Reply #15 on:** September 23, 2012, 12:56:31 am »

Guys....

...just a little off track.....

Is it true that standing on the border between USA & Canada you can witness the difference between 50 Hz & 60 Hz in their respective street lighting systems?...I am not sure which frequency belongs to which party....

raaartygunner .....do you mean like this? Derek

RAAArtyGunner · « **Reply #16 on:** September 23, 2012, 01:21:07 am »

Derek,

On the cast aluminium turntable is a small, about 50mm, disc with equally spaced black and white segments.

You place a fluorescent light above the disc and adjust the motor speed control until the black and white segments are stationary, if too slow, the lines will look to move anti clockwise, if too fast, clockwise, when speed is in sync with 50Hz, the disc will appear as stationary with clearly visible black and white segments.

The segments are similar to what opticians use when doing eye tests.

Am not able to provide a photo at this time.

derekwarner · « **Reply #17 on:** September 23, 2012, 01:52:30 am »

mmmmmmmmmmmm I am able to understand all that raaartygunner .....

If I powered up my turntable the same thing happens

but after two glasses of RED wine....those old technical terms of wow & flutter take over

.........Derek

RAAArtyGunner · « **Reply #18 on:** September 23, 2012, 02:17:45 am »

Derek,

Here is link to something similar,
http://www.vinylengine.com/strobe-discs.shtml

This one is more sophisticated than mine,
http://www.kabusa.com/strobe.htm

A better example of the disc but mine is much smaller,
http://www.superfi.co.uk/p-2594-project-strobe-it-turntable-speed-adjustment-disc.aspx

All as clear as mud eh what

sweeper · « **Reply #19 on:** September 23, 2012, 01:41:39 pm »

For general info:
A tube will actually extinguish as the supply waveform passes through the zero point on the cycle. Normal cure for the strobe problem in industry is to connect twin tubes to two different phases so that the lamps are actually 120 degrees out of phase with each other i.e one tube will remain on at all times.
In correspondence with a large manufacturer I was told "our tubes use powders in the tube that have an increased after glow and will, as a result, not display the fault to which you refer". Quite snotty they were about it.
As a lecturer in a college i/c electrical systems I found the answer very debateable. The fittings being used were twins using SRS starting (semi-resonant start) 50Hz but fitted with an additional capacitor to allow for operation on the local 60Hz supply. These capacitors proved to be rubbish.After a few months use the fittings became very fault prone (148 twins installed !). Our response was to change over to traditional switch start fittings.
My personal preference to cure the strobe effect was the use of an incandescent lamp on each machine tool - the old methods still work.
Hope this helps,
Regards,

nemesis · « **Reply #20 on:** September 23, 2012, 05:07:04 pm »

Hi, I would go along with what sweeper has said, I too have bulbs over my machines, good old anglepoise for the lathe, twist & turn any way. no problems at all KISS. Nemesis

NFMike · « **Reply #21 on:** September 23, 2012, 05:42:05 pm »

I think this is being a bit over done. Using a lamp with a hf electronic'ballast' will not have this problem and they are almost the standard these days and readily available at reasonable cost. I think most if not all compact fluorescents have electronic ballast.

Even using an old type where there is strobing, the effect is such that the moving part will be slightly blurred (and you can actually get a strobe effect even with incandescent lamps). In a home workshop where you will usually only have one machine running at a time noise will also help you know the thing is moving.

mrsgoggins · « **Reply #22 on:** September 26, 2012, 08:10:22 am »

Fluorescent lights are great but I accept that ther could be a problem if I was deaf, forgetfull, rather merry and my lathe was running at 3000rpm.
Only negative I have noticed is the effect on optical tacho's.

giovanni · « **Reply #23 on:** September 26, 2012, 12:06:27 pm »

They make tubes in LED lighting now with no mods. Just twist them in and flick the switch.

grendel · « **Reply #24 on:** September 29, 2012, 11:36:43 am »

interesting fact, you can make a flourescent tube without the ballast light up by lightly running your finger along the glass of the tube from one end to the other.
Grendel

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Author Topic: Fluorescent lighting (Read 13140 times)