Time clock and Eye!!!

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ashtrak

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We recently installed two contactors for platform lighting. The drawing specifies that the time clock work in conjunction with an eye. No problem with a contactor that is electrically held open, however both contactors are mechanically held (voltage to hold them closed and a voltage to open them). We are aware that we could add a relay with a set of contacts to do this. But we were curious if anyone had any ideas without adding more contacts. The drawing shows two wires coming from the eye going to the time clock (no schematic detail). Any suggestions???? Thanks
 
Typically when we install mechanically held contactors with more than one switching device, the devices are always momentary or pulse devices. Tork makes momentary time clocks that provide a two second pulse for on and a two second pulse for off. We usually install these with momentary SPDT switches in parallel which provide a manual override of the timeclock. Not sure however if someone makes a momentary pulse type of eye.
 
The first solution that comes to my mind is a simple ice cubr relay controlled by the photo-eye. NO contact closes contactor/NC opens it. I am not sure I have ever seen a momentary photo-eye but if you could find one, that would also work.
 
Jim,

Wouldn't that have possible conflicts if the time clock wanted to control the lighting contactor? I think with two controllers, you would need momentary signals to the mechanically held coil.
 
Good point hardworking. If the customer wants a timeclock on/photo-cell off operation (or photocell on/timeclock off), my scenario would not work.
It does make my brain strt to tick a little on the exact operation the customer is after. If it is a simple timeclock on/photo off situation, why not just let the timeclock send the on signal and the photo-eye send the off signal.
 
Once you go beyond one control device with a mechanically held contactor you'll need momentary controls. What is the function of the eye? Seems like with the time clock the eye might not be needed.
 
Is the purpose to turn on the lights at dusk and then turn them off at a specified time before dawn?

I wouldn't even bother with the eye. I would use an Intermatic Astronomical time clock and then you could set it for maintained or pulse.

I have installed several and not had any problems with them.
You could set it to come on before dusk if needed.
Very customizable.
 
Thanks for all the interest and replys. I think we are going to go with an external set of NO and NC contacts, they are specing the eye so we dont want to delete it. Thanks
 
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