Photo cell w/o contactor

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230323-0901 EDT

Isiash:

I do not believe you will find any commerical photocell that will switch much current. Possibly not more than milliamperes. Thus, I believe you are already really talking about a photodetector system that includes some sort of an amplifier ( relay ).

Thus, I believe you are looking for a photoetector system with a high enough output switching capability. This may mean you need to add some external relay to whatever is your available potodetector system.

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hillbilly1 said:
A quick search, and found this. They make heavier duty ones than this too.

Thermal Type Photocell, Stem and Swivel Mounting, Dusk-to-Dawn, 120-277V, Intermatic K4236C | 1000Bulbs.com

Shop for Intermatic K4236C thermal type photocell. Great prices and fast shipping on Intermatic thermal type photocells at 1000Bulbs.com!
www.1000bulbs.com www.1000bulbs.com
Click to expand...

This shows only 15A rating—If the fixture itself has an integral photocell there would be no need for an additional photocell , correct?


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Read up about the inrush of LED lights. For a half a cycle or so, it is extremely high. I don't have time the research it again now, but I remember that it can be hundreds of amps.
 
Strathead said:
Read up about the inrush of LED lights. For a half a cycle or so, it is extremely high. I don't have time the research it again now, but I remember that it can be hundreds of amps.
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Excellent feedback thanks


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Strathead said:
Read up about the inrush of LED lights. For a half a cycle or so, it is extremely high. I don't have time the research it again now, but I remember that it can be hundreds of amps.
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Sounds like a good reason to not energize them all at olne time as a single group.
 
Strathead said:
Read up about the inrush of LED lights. For a half a cycle or so, it is extremely high. I don't have time the research it again now, but I remember that it can be hundreds of amps.
Click to expand...
The cheaper LED’s do have a high inrush. Target bought some for their cosmetics display, and anything over 2 amps would trip a 20 amp Square D QOB breaker.
 
Please remember what the OP said: "just a simple photocell with open/close contacts." It's not a single photocell running the show! It's the contacts...
Now. How are those contacts rated??
 
PaulMmn said:
Please remember what the OP said: "just a simple photocell with open/close contacts." It's not a single photocell running the show! It's the contacts...
Now. How are those contacts rated??
Click to expand...

I believe they’re rated 15A


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synchro said:
Just be aware that if each fixture has its own photocell, then they won't turn on or off at identical times as the ambient light slowly decreases and increases over the day.
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Can the integral photocell within the fixture be ‘bypassed’ if desired in order to utilize an external photocell?


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Isaiah said:
But there is a limit as to how many contactor coils can be pulled in with one photocell.


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What limit? If the photocell can carry 20A when driving the load, it is not impossible to drive a contactor coil that draws only about 1,900 VA at inrush, sealed VA = 48VA (15.8A inrush, 0.4A sealed, size 8 contactor). You can use the auxiliary contacts of the first contactor to drive another contactor, and so on! Your only limitation is the VA rating of the control power transformer E.g. if you have to use 4 contactors, you'll need 48 X 4 ~ 200VA CPT.
 
topgone said:
What limit? If the photocell can carry 20A when driving the load, it is not impossible to drive a contactor coil that draws only about 1,900 VA at inrush, sealed VA = 48VA (15.8A inrush, 0.4A sealed, size 8 contactor). You can use the auxiliary contacts of the first contactor to drive another contactor, and so on! Your only limitation is the VA rating of the control power transformer E.g. if you have to use 4 contactors, you'll need 48 X 4 ~ 200VA CPT.
Click to expand...
And a second contactor activated by the aux contacts of a first contactor will have at least some delay in closing vs. the first one. That can only help in spreading out the inrush of the lights so that the peaks don't occur at exactly the same time.
 
topgone said:
What limit? If the photocell can carry 20A when driving the load, it is not impossible to drive a contactor coil that draws only about 1,900 VA at inrush, sealed VA = 48VA (15.8A inrush, 0.4A sealed, size 8 contactor). You can use the auxiliary contacts of the first contactor to drive another contactor, and so on! Your only limitation is the VA rating of the control power transformer E.g. if you have to use 4 contactors, you'll need 48 X 4 ~ 200VA CPT.
Click to expand...

Nice to know.
Where did you find the info on inrush and sealed VA? Thanks


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