Lux change in cells

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LinearSLI-H
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Lux change in cells

Postby LinearSLI-H » Tue Jul 05, 2011 8:29 pm

Heres a question for Danny, or anyone that knows, why was the Lux level in cells, changed from 80Lux, to 73?
This made me think, as I was having a brew in the kitchen, about half an hour ago, when my Astra 2 flicked into life, as a strom cloud came over, and then off again 10 minutes later as it passed.
My cell is one of the new ones at 73Lux, but the ones on the Beta 5s in the road, (RT P42s, at 80Lux), were not affected by the dark clouds.
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Danny
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Re: Lux change in cells

Postby Danny » Fri Jul 29, 2011 9:19 am

The LUX in alot of cells seem to shift over time, so from some of the cells switching on near full darkness, they may shift to being very sensitive and a cloud may make them switch on,

Was this cell that your onabout, one of them Greenbrook PEC1000 things, and not a propper made one?... I know all these new types of photocells that AREN'T made by the propper companies are very sensitive to dark, (they are a pain) always the very last photocells to go off on a morning and the first to come on at night.

Best photocells to use are the Thermal Royce Thompson- P3. or the Monostars and OASIS photocells. they don't seem to shift, plus are quite late coming on, and are early for going off (one of the 1st cells to switch off and last to come on)

They rate these photocells at 70 LUX on 35LUX off, Its not nessercerily true though as they come- on and go- off when ever they want lol

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LinearSLI-H
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Re: Lux change in cells

Postby LinearSLI-H » Fri Jul 29, 2011 2:14 pm

The one I have in now, was one that came off my Thorn Beta 2 SOXPAK, the one that came with the kit went `dayburner` last summer.
I have plenty of RT nemas as spares though ;) .
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Re: Lux change in cells

Postby Paul » Fri Jul 29, 2011 6:29 pm

From what I can see, your photocell is in the shadow of the eaves of your house, so would be in a darker place than a lamp post out in the middle of the street... perhaps means it would switch in quicker?

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Re: Lux change in cells

Postby LinearSLI-H » Sat Jul 30, 2011 11:50 am

The cell is not on the lantern mate, its bolted to the waste pipe level with the gutters, with the cell eye pointing outwards ;)
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Re: Lux change in cells

Postby SuperSix » Sat Jul 30, 2011 7:20 pm

Cells are still available with different switching levels, 70 Lux on seems to be the most common these days. I'm not sure why manufactures shifted over to a slightly lower switching on level, maybe because the majority of photocells have to switch discharge lamps and the majority of installations today use SON and MH lamps which warm up a lot faster than SOX and MBF lamps. Seems like a rather crap guess of an explanation though :oops: I really don't know.

As you know the switching levels drift with age, generally to a higher level so lanterns end up switching on early and off late. Occasionally they seem to drift the other way and don't switch until it's almost completely dark before failing completely, not a common one but I've seen it happen with a few photocells round here. Electronic photocells are generally better if you want constant switching levels throughout photocell life, the only problem is a shorter life compared to thermal photocells.

If you've got the cell pointing horizontally then this will increase the switching level, could be the reason why something like clouds caused the switch on.


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