How to change to photoeye instead of time clock?

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ksstang

Member
Location
Lawrence, KS
Hello everyone. I'm new here, and for some reason having a bit of a brain fart. My background is electrical, and I attended Pittsburg State University in Pittsburg Kansas. I received my associates degree in Electrical Technology. I graduated back in 2002.

So, now that I have my introduction complete, I'm for some odd reason stumped on a issue I was asked to look into at work. I don't know why, as I don't think its probably that hard, but, I'm having issues. If I need to I can probably draw up a diagram if it would help everyone out.

Here where I work all our lighting is 277v. Our outdoor lighting is split up between a contactor in a penthouse in the roof that controls "JUST" the roof lights, and then 2 contactors in the basement that control all the parking lot lighting, and exterior building lighting. Those two lighting contactors are side by side with a mechanical time clock in the middle of them that turns them on and off.

They would like that mechanical time clock removed, and a photocell installed in its place so that there is no more having to change the clock as the sunset/sunrise changes throughout the year. The roof contactor can stay on its time clock, as there is only roughly 10 lights that are on that.

So, after looking at that mechanical time clock and the two contactors I believe its 120v that operates the coil, and when it activates it sends the signal to each of the two lighting contactors to activate the outdoor lights.

I snapped a few pictures of what I'm dealing with, and hoping someone can point me in the right direction of how I would go about removing the time clock and putting a outdoor photocell in its place. I have room to run conduit from the exterior down to that area to get wires from the photocell, just confused on hooking it all up and making it work properly.







 

Dennis Alwon

Moderator
Staff member
Location
Chapel Hill, NC
Occupation
Retired Electrical Contractor
Firstly, they make an astrological time clock that changes with the seasons. Secondly this is very basic hookup and if you are having trouble with it then I really don't think you should be wiring this. I would get an electrical contractor in there to do the job.
 

ksstang

Member
Location
Lawrence, KS
Firstly, they make an astrological time clock that changes with the seasons. Secondly this is very basic hookup and if you are having trouble with it then I really don't think you should be wiring this. I would get an electrical contractor in there to do the job.

Ok, well, I am perfectly capable of doing the work, I was just confused at the moment. If I'm thinking properly wouldn't you take 120 out to the photoeye, and then the other side of the photoeye back to the 120v side of the contactors?
 

ksstang

Member
Location
Lawrence, KS
Firstly, they make an astrological time clock that changes with the seasons. Secondly this is very basic hookup and if you are having trouble with it then I really don't think you should be wiring this. I would get an electrical contractor in there to do the job.

I might look into one of these. I am absolutely perfectly fine performing the actual work, I just wanted to make sure of the connections to be sure first.
 

ksstang

Member
Location
Lawrence, KS
You might connect with mgookin on this site. link to his profile: http://forums.mikeholt.com/member.php?u=137248

His company makes a slick unit that replaces photocells, has a 15 year warranty and adjusts for sunrise / sunset.
It has a gps unit in it to compensate for time changes.

Here is the website of the unit: http://applied-physics-laboratory.myshopify.com/

He will also likely chime in on this thread when he sees it.

Ok, thank you! That does look pretty slick!
 
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david

Senior Member
Location
Pennsylvania
I don't think you are having trouble with the photo eye you are having trouble incorporating that control into a latching contractor

you may need two photo eyes one with light on function and one with a light off function. you can google latching contractors wiring diagrams
and you can also google photo eyes to review your options

edit its light on function
and dark on function (not light off function)
 
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david

Senior Member
Location
Pennsylvania
I guess a more common way of incorporating a standard photo eye into a latching contactor would be to wire the photo eye through a relay with normal open normal closed contacts
 

david

Senior Member
Location
Pennsylvania
I guess a more common way of incorporating a standard photo eye into a latching contactor would be to wire the photo eye through a relay with normal open normal closed contacts

I think this should work for you.
 

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david

Senior Member
Location
Pennsylvania
Not a very clear image
relay 1 shown on bottom line controlled by a dark on photo eye

Photo Eye activates: photo eye NO contacts close
Relay one NO contacts close in series with Contactor NC Aux. Contacts activates contactor one and latches in the on position.

Daylight photo eye deactivates relay one normally closed contacts close in series with contactor one Normally open Aux. contacts that are being held closed in the on position. Activating the un- latch for contactor one.

Note: incorporating two photo eyes replacing relay one;
Remove relay one, replace relay one NO contacts with a Dark On Photo Eye
Replace relay one NC contacts with a Light On Photo Eye
 

sparkyrick

Senior Member
Location
Appleton, Wi
I don't think you are having trouble with the photo eye you are having trouble incorporating that control into a latching contractor

you may need two photo eyes one with light on function and one with a light off function. you can google latching contractors wiring diagrams
and you can also google photo eyes to review your options

edit its light on function
and dark on function (not light off function)

Couldn't he just remove the latching/unlatching contacts and wire the photocell directly to the contactor coil. Or are those coils not rated for continuous duty?
 

kwired

Electron manager
Location
NE Nebraska
Couldn't he just remove the latching/unlatching contacts and wire the photocell directly to the contactor coil. Or are those coils not rated for continuous duty?
Not completely certain how the latching works either, but apparently needed a latch and unlatch signal previously - why not drive a simple double throw relay from the photocell and let it transfer from latch to unlatch according to whatever is needed, it basically replaces the time clock switches.
 

Fulthrotl

~Autocorrect is My Worst Enema.~
Firstly, they make an astrological time clock that changes with the seasons. Secondly this is very basic hookup and if you are having trouble with it then I really don't think you should be wiring this. I would get an electrical contractor in there to do the job.

secondly, intermatic makes a 365 day astro timeclock in single or double channel,
that will fit perfectly inside the existing enclosure. takes about 15 minutes to change
and program.

and if you have latching contactors you don't wish to redo, getting a two channel
and using one to turn the lights on, and one to turn them off would work.
just make sure you don't have overlap of the channels.
 

Strathead

Senior Member
Location
Ocala, Florida, USA
Occupation
Electrician/Estimator/Project Manager/Superintendent
Anyone else surprised with this? I have always been under the impression that a latching relay is supposed to receive a momentary control signal, not a maintained one. In this wiring the on and off pulses are maintained. I would have expected the contactors coils to burn up long ago.
 

david

Senior Member
Location
Pennsylvania

It would be a momentary control signal if in series with the contactors normally closed aux. contacts

Edit: may need a cleared picture but I thought the Latch coil was run through Aux contacts 2A
 
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Fulthrotl

~Autocorrect is My Worst Enema.~
Anyone else surprised with this? I have always been under the impression that a latching relay is supposed to receive a momentary control signal, not a maintained one. In this wiring the on and off pulses are maintained. I would have expected the contactors coils to burn up long ago.

i don't know that maintained power will hurt a latching contactor.
it just needs a pulse to turn it off and on, but after it gets the pulse
and latches, doesn't it disconnect the pull in coil until it's reconnected
by an input to go the opposite way?

in any event, that two pole intermatic 365 day astro clock has momentary
outputs, iirc.
 

kwired

Electron manager
Location
NE Nebraska
Anyone else surprised with this? I have always been under the impression that a latching relay is supposed to receive a momentary control signal, not a maintained one. In this wiring the on and off pulses are maintained. I would have expected the contactors coils to burn up long ago.

Looks to me like the lower portion is just a latching relay - the main contactor is not latching and the main contactor coil has to be energized to close the power contacts. All the latching relay is doing is being a holding circuit instead of an aux contact on the main contactor.

If I am correct one could easily eliminate the latching relay and directly drive the main contactor coil from a new timer or photocell.
 

infinity

Moderator
Staff member
Location
New Jersey
Occupation
Journeyman Electrician
not sure about the ones in this thread but ASCO 917 latching lighting contactors coils can be wired for either pulse or constant ON because they have auxiliary switches that prevent constant power from going to the coil. A twelve pole contactor can be controlled with a 3-wya switch.
 
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