|Neil Wyatt||13/10/2018 18:21:47|
18232 forum posts
The current flow is almost all electrons from cathode to anode. Presumably they need some distance to build up speed and the anode end is brighter.
|Andrew Tinsley||13/10/2018 18:24:15|
|1179 forum posts|
The use of three phase in an office would go someway to reducing 100Hz flicker. Good point Frances! However I think the flicker most if not all people see with choke fed fluorescents is NOT 100Hz, but flicker due to near end of life effects.
|Neil Wyatt||13/10/2018 18:30:57|
18232 forum posts
No, I've found it on Wikipedia.
Under Electrical Ballast:
"In ballasts that control two or more lamps, line-frequency ballasts commonly use different phase relationships between the multiple lamps. This not only mitigates the flicker of the individual lamps, it also helps maintain a high power factor. These ballasts are often called lead-lag ballasts because the current in one lamp leads the mains phase and the current in the other lamp lags the mains phase. "
Under Fluorescent Lamp:
"Even among persons not sensitive to light flicker, a stroboscopic effect can be noticed, where something spinning at just the right speed may appear stationary if illuminated solely by a single fluorescent lamp. This effect is eliminated by paired lamps operating on a lead-lag ballast. "
|1709 forum posts|
As Neil says Thorn lighting used to sell matched lead/lag flurouscent lights to not only improve PF but also reduce strobe effect.
In the 1970' and 80's most electrical specifications for factories where machinery was to be be used stated the need to connect lighting in large areas using all 3 phases to reduce strobe effect.
Edited By Emgee on 13/10/2018 19:03:27
|Frances IoM||13/10/2018 19:55:38|
|831 forum posts|
|in the very large open plan offices in the late 70s and 80s tubes were changed on a regular schedule irrespective of use but designed so that all tubes were replaced well before end of life - one feature I was due to add to control software was to report on actual usage of each tube but I left the consultancy before it was approved. I suspect that the cost of tubes was small wrt labour cost to change them and that a fixed sweep through a floor was cheaper to administer. In those days complete floors of dealers would be switched around between European, Japanese + American business hours over a night with partitions etc also moved - all our testing was done between 1am and 3am.|
Edited By Frances IoM on 13/10/2018 20:01:50
|Adam Harris||15/10/2018 15:33:40|
|470 forum posts|
For those interested in the tripping of the 30mA RCD problem, I have now independently switched all 5 twin HF 70W "Viper" fluorescents rather than wiring in parallel and if switched on one after the other, they work absolutely fine with no RCD tripping. Thus it must be the start up surge that trips the RCD when more than one is started at the same moment. There is no evidence of running earth leakage from 700w of this fluoresecent lighting which was my other concern.
|Adam Harris||15/10/2018 15:34:13|
|470 forum posts|
They are extremely good and cheap lights
|997 forum posts|
Glad your sorted Adam.
For some time, decades have run cheap fluorescents likes of Wickes from a 4 bank switch.
Only time notice any flickering whatso ever is when a tubes on its way out.
Have seen some sellers stating the K rating for fluorescents, lower the softer whereas high 6000K its whiter and 'seemingly' brighter along hurtful eyes and shadowing with led! When a tube goes i just pop down to local hardware and buy one there and then paying over the odds around £4.
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