I have an IKEA Norrsken set of lights - a transformer, two cables that strecth across the ceiling to suspend individual lights from, and a set of lights.
The English instructions say: "not designed to take more than 5-7 spotlights. Max 140W."
The Italian instructions say: "designed for 5-7 spotlights. Max 140W."
These don't mean the same thing!
The Portuguese sounds more like the English: "mais do que 5-7" and the French more like the Italian: "the system can only support 5-7 spotlights".
So, the transformer is rated for 140W; what would likely happen with only say 4 lights mounted on the cable tracks?
Is the transformer a large heavy thing or small and light weight?
If it's large and heavy it's a lump of iron with windings, if it's not properly loaded the voltage might be a bit high, shortening the life of the bulbs present.
A smaller light weight transformer is most likely electronic and will have much better regulation and having a lower load on it shouldn't be a problem.
Of course the other problem with that description is that bulbs come in different wattages. You could have 7 x 20W = 140W or 2 x 50W + 2 x
20W = 140W. Assuming the fittings are rated for a 50W bulb...
12V lighting transformers have no active voltage regulation, and rely on the load being within a given range to keep the output voltage within limits. That's why you'll see ratings like 20W-60W. Something like that should be on the transformer's rating plate.
Electronic transformers have a low internal impedance, and the min output is usually less than half the max output. Magnetic transformers have a much higher internal impedance and usually can't cope with such a wide load range whilst keeping the output voltage within spec, and the min load may be nearer to the max load.
All the electronic transformers I've come across will auto shutoff with too low a load, but I don't know if that's the case with all of them. Magnetic transformers don't have any such auto-shutoff.
Is it a transformer or power supply? A transformer will be heavy - a PS not.
If a PS it will usually give the load range on it - like say 50-150 watt or whatever. A transformer will supply a slightly higher voltage if not running at full load so the life of the bulbs may suffer.
A 140w 50Hz transformer might have a regulation of around 5 or 10%.
4x20w=3D80w, so the output voltage would have increased from max load level to the same plus 2.5-5%. If the transformer is designed to be say 1.5% undervoltage at peak load, the overvoltage would now be
1-3.5%.
life is proportional to voltage^13
efficacy is proportional to voltage^1.9
color temperature is proportional to voltage^0.42
So mean bulb life would shift from 1500hrs to 1320-960 hrs efficacy would improve 1.9% - 6.7% CCT would move up from 3000K to 3012K - 3043K
You will probably get through bulbs quickly... Assuming its a typical ikea iron cored lump, then its output voltage will rise out of spec if lightly loaded.
The simple fix is to extract the transformer and replace it with an electronic one of appropriate size.
replying to John Rumm, Nicolas wrote: I have the same set. It was run with 6x20W halogen bulbs since 2005 and not a single bulb has burn in this time period. Two months ago, I replaced all the halogen MR16 with Philips LED 6.5W plus a Lutron Casetta Dimmer. Since then, the whole rail has a tendency to flicker.
I know that the load has gone from 120W to 39W so the load might be too low. Also, I undertand that dimmers don't work all the same between ELV, forward phase, reverse phase, TRIAC. This is not common language to me as it's hard to find the spec of this old tranformer | power supply, the Casetta dimming mode and the preferred dimmer of thos Philips bulbs.
Being already in mid 2018, what would you suggest, John, to solve the problem ?
Ohm that weird web site again. Right I have a 12 v transformer from Ring lighting. all it is is a crude transformer in a box supplying AC at nominally 12 v. and to my mind trying to get leds to work may well be as crude as them only running on one mains half cycle. does anyone actually know if these are really able to use the ac
12v or are they crudely rectifying one cycle of the ac internally? I am in the market for new garden lights as the old ones tungsten filament ones are now intermittent. I need bulbs that can illuminate a globe visible in the dark. My sight is almost down to light perception and I really need a large blob of light to be able to see where my property is. Brian
Not sure there is any benefit in using 12v LEDS over mains. Dimmable 12v LEDs are rather more expensive than mains ones too. TLC suggest if you want to dim them you need a purpose transformer and dimmer.
I have a chain of GU10 on a dimmer which work pretty well. So might have made more sense to convert your fittings to those - if possible.
But since you've already bought them, I'd investigate a transformer designed for dimming LEDs.
12V is the only option in this case, since the lamps are suspended from a pair of uninsulated support wires that stretch across the room. They also carry the power.
Yup that would be my fix, swap out the iron lump transformer in the wall mounted bit, and put in a suitable electronic transformer.
Not cheap, but you get what you pay for. I've got some of the same make, non dimmable.
Key things I like about this range:
1) Proper cable terminations, shrouded with strain relief. I am really not sure how some of the junk sold in wholesalers with single insulated wires sticking out can possibly be made to conform to IET Wiring Regs unless you re-enclose the whole thing.
2) Over-everything protection. I prefer my SELV PSUs to not catch fire...
However, I did get a cheaper SELV unit from TLC a long time ago driving
12V incandescent.
However, in neither case can I vouch for how well they will work with LEDs.
There's another solution, which is to have an always on 24V SELV PSU, non dimmable and use a remote dimmer module:
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That's cute as it will do mains OR 24V (but not 12V). 24V LEDs are not uncommon.
It's really a ZWave device, but it can be hard wired to a push button switch (various momentary switches are available, GET/Schneider do a nice GRID push button and for pull cords, use an MK "disabled" alarm and swap the red cord for white - the switch body is the same as normal.
I've done that, but on mains with Fibaro dimmers - but I am considering adding Qubinos for 24V LED dimmable lighting upstairs (and maybe even RGBW).
The few 12V G4 LEDs I've dissected all have full wave rectifiers. If they are marked not dimmable, they have a smoothing capacitor too. Otherwise they flicker at 100Hz, which is only noticable if they are moving across your field of view (or something they are lighting is moving across your field of view) and this is not really an issue.
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