Photocell in series.

[djtazjr]

I know this will sound kind of silly, and even very simple for you engineers and experienced elictricians in this forum, but can anyone explain to me how to wire a photocell in series with a 120volt single pole 24hour dail timer with the photocell overriding the timer?

A ladder diagram would be appreciated if at all possible.

Thanks in advance!

 

[bphgravity]

Re: Photocell in series.

The only way I can see allowing the photocell to energize the light regardless of the timer setting is by having the photocell and timer in parallel. This way the timer or the photocell can energize the light. Any series connection will result in the second device being depedent on the device ahead of it.

 

[roger]

Re: Photocell in series.

Bryan, you are right in both cases, but in many installations it's desirable to turn some lights off at a given time and this can be achieved by simply running the switch leg of the photo cell thru the time clock switch contact/s.

In the second condition we would set the time clock to activate (turn on) at a given time before dark and let the photo cell drive the operation after that, then we would let the time clock dictate the off time.

We get into some pretty elaborate installations using this method along with contactors to leave some lighting on for the duration of darkness and switch other non essential lighting off.

Roger

 

[roger]

Re: Photocell in series.

Djtazjr, sorry I didn't really answer your question, but think of running the Photo Cell switch leg thru the time clock, you will need a clock with a set of dry (auxiliary) contacts. If some one doesn't post a diagram by tomorrow I will make an attempt.

Roger

 

[hbiss]

Re: Photocell in series.

...with the photocell overriding the timer

You need to specify how the photo control (NOT photocell!) is to override- is it supposed to turn the lights on at dusk with the time clock turning them off at a preset time, or something else.

Since you say "series" it sounds like this is what you want. Simply wire the photo control as you normally would (hot & neutral) and connect the switched (red) leg through the time clock contacts to the fixtures. Be sure to remove the hot jumper factory installed between one side of the contacts and one side of the clock motor and supply power to the clock motor separately.

Keep in mind that the photo control should come first so it will always be hot (if at all possible) since many take time to "warm up" before they will operate when power is applied.

So simple that a diagram should not be needed unless you have in mind something else...

-Hal

 

[djtazjr]

Re: Photocell in series.

So "photo control" in "photocell", Makes me upset when people try to get technical and make others feel belittled.

Thanks for the help an bphgravity. The ladder diagram is for my Boss. He likes those sort of things.

 

[roger]

Re: Photocell in series.

Hal, to stay with the conversation, let's stick with the generic term of "Photo Cell".

To expand on this, is a relay a contactor or can a contactor be a relay?

Is a contactor a switch or a switch a contactor?

When I want to buy a "Photo Control Device", I call my supplier and ask for a "Photo Cell", then specify voltage and other pertinent details.

Roger

 

[caosesvida]

Re: Photocell in series.

a contactor is handles over 20 amps and a relay is under 20 amps. But we tend to interchange them.

 

[hbiss]

Re: Photocell in series.

Makes me upset when people try to get technical and make others feel belittled.

djtazjr, we are all here to learn and there is no need to feel belittled, that wasn't my intent. NONE of us know everything! This IS a technical trade!

let's stick with the generic term of "Photo Cell"

Generic for whom? Probably only us and wrongly at that. What does it say on the box? "Photocell" to anybody involved with electronics and many other technical fields has a completely different meaning. Say "photocontrol" though and everybody will know what you are talking about.

As for contactor vs relay, a contactor is a relay but there is no fine line between the two. A contactor would normally be large and be capable of handling a large amount of current and normally used for switching power loads.

A relay is anything from micro miniature to that which can handle a sizable amount of current. Relays are available with any number of contacts and configurations.

A contactor or relay is not a switch since "switch" implies a manually operated device however they do switch a load. Clear huh?

-Hal

 

[roger]

Re: Photocell in series.

Hello Hal,

A contactor or relay is not a switch since "switch" implies a manually operated device however they do switch a load. Clear huh?

Well how does the word "Switch" work with Autotransfer in front of it?


Now back to the "Photocell"

Generic for whom? Probably only us and wrongly at that. What does it say on the box? "Photocell" to anybody involved with electronics and many other technical fields has a completely different meaning. Say "photocontrol" though and everybody will know what you are talking about.

seems as though Tork may also have it wrong.

Roger

 

[hbiss]

Re: Photocell in series.

That is because that IS a photocell, it works with that control unit.

-Hal

 

[roger]

Re: Photocell in series.

Hal, I'm also talking about the labeling of the termination points, hence the generic term "Photocell" when speaking of such connections.

Roger

 

[hbiss]

Re: Photocell in series.

Dunno Roger, looks like the EPC1 photocell connects to terminals 1 and 2 of the remote input block. I do see that the EPC1 symbol is labeled "photocontrol" probably be mistake. Everywhere else it is properly refered to as a photocell as evidenced by the two white control wires.

-Hal

 

[iwire]

Re: Photocell in series.

Originally posted by hbiss:
Dunno

Is dunno the correct terminology?


Just kidding.

Bob

 

[richwaskowitz]

Re: Photocell in series.

Don't bother. I have been screwing around with this exact same scenario for years, trying to get lights to come on at dusk and off at a preset time. Finally, Intermatic came out with a programmable timer that keeps track of the date and adjusts the sunset and sunrise times automatically and even accommodates daylight savings time. You simply tell it what time its, what the date is and where in the country you are and it takes care of the rest. It has a battery back-up too. You can program it to turn on at preset times or simply "dusk" and off at preset times or "dawn". Did I mention it was inexpensive too? ($30).

 

[roger]

Re: Photocell in series.

Rich,

Don't bother. I have been screwing around with this exact same scenario for years, trying to get lights to come on at dusk and off at a preset time.

I don't understand what would be so difficult? As I said earlier, we do many things with a time clock, photo control,(that was for Hal, ) and contactors, this is actualy pretty simple.

Roger

 

[djtazjr]

Re: Photocell in series.

Didnt feel belittled just had a bad day that day and took it out on the forum.

By the way isnt that called an Astronomical Timer?

 

[richwaskowitz]

Re: Photocell in series.

When I said "screwing around" I was alluding to using two devices to do the job instead of one. I wasn't implying it was difficult to get to work. I remember the old mechanical astronomical timers. They were expensive, and although they adjusted for seasonal changes, they did so for all presets and one could not turn on or off at a fixed time and sunset/sunrise both and they did not account for daylight savings time. These microprocessor jobs are pretty slick.