It is currently 28 Mar 2024, 10:55
Malc2098 wrote:Andy,
I have had to look at the possible effects to people with photo sensitive epilepsy, and I have a family member who's suffers, so there was a personal as well as professional interest.
The first was relating to the siting of wind turbines. I cannot lay my hands on the research at the moment, but the speed at which the turbines revolved never exceeded 19 rpm so as flicker did not induce PSE.
The second was to provision of intelligent road studs within the road environment. IRSs are 'cats eyes' that are lit by LEDs that are powered from button cells charged via solar panels on the top of the stud, or in some cases, hard wired from an external power source. There was a complaint on a major road where these were fitted, that a sufferer, a passenger in a car, felt sick while being driven along the road. Others on this forum can state the frequency of the LEDs, but if there were any photo sensitive effect at all at that incident, then the consensus was the likely gaps between the studs and the speed at which the car was passing them, relative to sufferer's sensitivity. So, if there was a linked effect, again the consensus was that it was random because of the three factors, two of them, speed and sensitivity are likely to be different each time.
I'm not sure how much that might help, but the inference was that it was not the perceived flicker of the LEDs that contributed to the sufferer's feeling of sickness.
Hope that's some help.
greeno wrote:LEDs are all DC so you shouldn't have any worries.
The AC is always chopped into DC by something inside the unit.
greeno wrote:LEDs are all DC so you shouldn't have any worries.
The AC is always chopped into DC by something inside the unit.
Robert wrote:Conventional (been around for years) control gear for fluorescents just regulates the mains current so it will operate at 50Hz and flicker. Electronic control gear (probably the only type you can buy now) operates at around 18KHz so it will have no flicker. So get a new fluorescent fitting if you want no flicker.
Tusses wrote:I know my laser cutter runs at about 25KHz , and DOES flicker. if you cut a line fast enough you can see the pulses in the cut.
Most people with photosensitive epilepsy are sensitive to 16-25 Hz, although some people may be sensitive to rates as low as 3 Hz and as high as 60 Hz.
Rod wrote:Like Trailing Edge dimmers.
Rod
Simply described, the (HF) ballasts contain three sections. A filter that protects the device from the irregularities in the mains supply and prevents RF and other interference to and from the ballast. A second stage that converts the 50Hz AC supply to DC and a third that consists of an inverter that supplies the lamp at high frequency with the correct voltage. This last section also includes a circuit that enables the preheating of the lamp where required and which is important for maximising lamp life.
Operating at anywhere between 20,000 and 40,000 Hz they consume up to 30% less power whilst producing the same amount of light. They are also quieter, lighter and have the potential for Dimming. There is no need for any additional components such as a starter or capacitor and this makes them quick and easy to install.
Andyp wrote:Ok, so what I have is not high frequency?
Just found thisSimply described, the (HF) ballasts contain three sections. A filter that protects the device from the irregularities in the mains supply and prevents RF and other interference to and from the ballast. A second stage that converts the 50Hz AC supply to DC and a third that consists of an inverter that supplies the lamp at high frequency with the correct voltage. This last section also includes a circuit that enables the preheating of the lamp where required and which is important for maximising lamp life.
Operating at anywhere between 20,000 and 40,000 Hz they consume up to 30% less power whilst producing the same amount of light. They are also quieter, lighter and have the potential for Dimming. There is no need for any additional components such as a starter or capacitor and this makes them quick and easy to install.
So should I be able to replace my existing chokes with HF ones?
Robert wrote:Tusses wrote:I know my laser cutter runs at about 25KHz , and DOES flicker. if you cut a line fast enough you can see the pulses in the cut.
Surely if the laser was flickering at 25k you would see it when static and not just when cutting. The flicker when cutting must be down to reflections from the waste during the cutting process?
wikipedia says we cant see much past 60Hz
https://en.wikipedia.org/wiki/Flicker_fusion_threshold
There is a reference to 500Hz in extreme people in the notes..
9fingers wrote:Andyp wrote:Ok, so what I have is not high frequency?
Just found thisSimply described, the (HF) ballasts contain three sections. A filter that protects the device from the irregularities in the mains supply and prevents RF and other interference to and from the ballast. A second stage that converts the 50Hz AC supply to DC and a third that consists of an inverter that supplies the lamp at high frequency with the correct voltage. This last section also includes a circuit that enables the preheating of the lamp where required and which is important for maximising lamp life.
Operating at anywhere between 20,000 and 40,000 Hz they consume up to 30% less power whilst producing the same amount of light. They are also quieter, lighter and have the potential for Dimming. There is no need for any additional components such as a starter or capacitor and this makes them quick and easy to install.
So should I be able to replace my existing chokes with HF ones?
Yes. Be aware that most HF ballasts run tubes in pairs. Your fitting appears to be a twin so that is fine.
Check the size of the HF ballast - usually convenient slim cross section - to make sure it fits inside the existing casing.
Sometimes the terminals are push in (once in never out) that require solid core wire. Your existing fitting will possibly use this sort of wire so retain the wire for reuse. the size required is not usually available as a diy item.
The HF ballasts are simply L,N&E in and four wires out to the tubes. They will only work with both tubes.
fitted. Have you spotted the problem?? When one tube fails, you don't know which it is so you need to juggle the new one with each of the old to get a working combination, or just change them in pairs.
Remove the chokes, power factor correction capacitors and starters.
Capacitors can be kept for motor replacements although low values only tend to be any good for sub horsepower motors.
Bob
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