- Location
- Tennessee NEC:2017
- Occupation
- Semi-Retired Electrician
Thanks!
I could have used something like that way back when I was taking some of the courses using ladder logic.
lighting relays and time clock
- Thread starter Oohitec
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Thanks!
I could have used something like that way back when I was taking some of the courses using ladder logic.
hillbilly1
Senior Member
- Location
- North Georgia mountains
- Occupation
- Owner/electrical contractor
Nice! I still have to draw in MS Paint, on one of my old computers I have a free ladder logic program that you can build and test circuits, I would have to dig it out it of a pile of laptops. I have not tried to cut and paste from it. I usually have to draw circuits for non-control electricians, so I have to simplify it because they don't understand the symbols.
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The "scheme" I presented doesn't wait for either clock ON or OFF to reset when the key switch is in the AUTO position. As hillbilly said, if the owners want to remove the key in the override state, simply install a switch operator which permits key removal in one or both override positions. The only issue I see with that is forgetting to return to AUTO. If that's a problem, there are several options. The simplest option is to add a TDR for limiting the override condition or for providing a notification, or both.
Now if "lights off" is to ultimately be left to the time clock, where no override ON is permitted under time clock OFF condition, that amounts to no override ON at all... so simply remove the override ON portion of my "scheme".
hillbilly1
Senior Member
- Location
- North Georgia mountains
- Occupation
- Owner/electrical contractor
Here is a ladder diagram that will allow the key to be removed, and the lights reset when the timeclock goes through the next cycle. When the key switch is turned right, the lights are turned on, if turned left, the lights are turned back off, providing the time clock is calling for them to be off. I have to find my photobucket account, it's another small diagram!
No offense taken... I really appreciate your time and knowledge.After talking with tech support from the time clock. The tech said that the second set of terminals in the time clock go to the second relays's N/O & N/C contacts(After looking at the parts provided... I realized that the relays only accept 120V and not the 277V I am providing)I'm sending and RFI to the engineer to clarify his schematic. Thanks again guys
Glad to hear.
The [Tork] tech doesn't know your particular design, and is likely making one or more assumptions. The second set of contacts are electrically independent of the first, but their timing operation is identical. Unless reverse operation is desired, put the second relay on the second set of contacts makes no difference. The only one that can answer your questions regarding control of the second contactor is the design engineer.
Who did the ordering? If not the design engineer and they ordered off the print, I can see why. Voltage is not specified... neither are exact part numbers for the contactors and relay. Whomever did the deciding on the part numbers apparently didn't know this is a 277V control setup. Other than the time clock part number, there is no indication of voltage on the print.
The ASCO 917 part numbers would be 917122071 C and 91762071 C. The C on the end is for the contactor in a NEMA1 enclosure per print. But I would just drop the C and put everything in one larger NEMA1 enclosure, since you do need an enclosure for the control relay, too (RFI for revision and make sure confirmation is documented). The control relay make and model is not specified at all. A basic 3PDT "ice cube" relay with 277V coil voltage (and socket) should suffice. Oh, and don't forget the switches must be rated for 277V also.
Having 120V parts in hand, it may be decided to use 120V control, with the exception of the timeclock motor, provided the model spec'd is actually the one received.
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