ECN Forum Forums General Topics of the Trade General Discussion Area Photocell 120v 1ph

I encountered something new today about phototcells, but I'm still unsure of how or why I had the problem.
A 120v photocell was cycling on/off in intervals of about five minutes. Now there was a lighting contactor 120v on the load side that pulled approximately .75amps. Also on the load side was two ice cube relays that were 120v coils, that pulled at best .5amps. they were a (honeywell)"for hvac" style relay. that was used to contact other hps lighting. and one neon light.
My first guese was a bad photocell, but I have never seen one cycle before, so further testing was done. by process of elimination.
When the two "honeywell" relays were unhooked from the load side, and only the lighting contactor was hook-up than the cycling would not happen any longer.
Was it all pulling too many amps ? NO. I determand this early on. Even at that is it not that the photocell is rated for it's draw, 15/20amp depending on the rating.
Both "honeywell" relays worked properly.
Was the resistants to high across the three coils ? causing the photocell to see more of a load than what was real. in this case if it exceeded the breaker rating, than why was it not tripping ? (porperly rated). With a digital amp meter the amperage was never a question.
History: the photocell cycled once before, a electrician replaced it about a month ago. I believe he tested the lights in the day, seen they where on, then left. A month later it was noticible they were cycling again. So a new electrician was called. So the photocell was 1 month old. The other relays got hook-up during a remodel, about a year ago. So it's a good possibility that this worked for up to a year in this manner.
I have only seen a photocell good or bad.
It was all wired to code, the "honeywell relays was removed, and the other lighting was routed to the lighting panel, controlled by the lighting contactor. All works fine now, but I'm still dont know why it was cycling ????????

P.S. All testing was done with tape over the eye. SO false lighting was not a problem.

Several questions.

First are all of the relays chattering on and off, or just the "honeywell" ones.

Are all of the lamps cycling? The cycling sounds like the normal end-of life for many HID lamps.

What is your actual supply voltage to your photocell? The leakage current through your cell may be high enough to turn on your relays with no lamp load. As the lamps come on the voltage drops causing the relays to drop out.

Try adding a larger load to your photocell (like a 60W incandescent lamp) in parallel with your relays.

First there was no relay chattering, You did not read the story very well. The photoeye was cycling on/off at intervals of about five min. Chattering neams: on/off very fast.
The lamps only cycled becouse the load side of the photocell cycled.
the power to the photocell is seperate than the power of the lights. The photocell controled the coils only

Sorry for the poor choice of terminology. But it doesn't change my train of questioning.

While cycling, is the off time the same length as the on time? Also does the cycling occur during "light" or only during "darkness"?

Are all of the relays affected or just the "honeywell" ones?

"You did not read the story very well. "

Aphares,
JBD is trying to help you out here.....being rude is probably not the best way to go.

GJ

What's this about the "increased resistance of the 3 coils" causing the load to go up over 15A?? Please explain this! Some kind of reverse physics?
The "Honeywell" relays are called Octal Base Relays, they're not just for A/C use. We use them on all kinds of control circuitry, and the ones we use are UL listed for the purpose.

Didn't mean to get rude, or for that matter didn't Mean it in a rude way. SORRY....
The problem was eventualy found. A hair line crack in the circuit bourd of the photocell was getting hot(shutting off), then cooling down (turning on), When the load was decressed then the bourd did not get hot enough to cause the same effect. Untill it decided to just go bad all together. Alot like finding a needle in a hay stack, until you remove all the hay, then there it is. Solved the most inportant problem though. The wiring was not per code, and was fixed propperly trying to find the other problem. Sometimes the answer is just infront of your nose, I was just trying to use your guys nose though. Thanks. aphares

I notice that this exact same question is also posted in the Theory Section. That's really not necessary. The collective "nose"
will sniff it out easily enough.