Dismiss Notice
Join Physics Forums Today!
The friendliest, high quality science and math community on the planet! Everyone who loves science is here!

120-240VAC Digital Logic Power Relay Timer

  1. Jul 9, 2013 #1
    Design Goal:
    Remove power from 4 washing machines and 4 dryers using relays and a digital logic timer.
    (9 Hour cycle of no-power from 22:00 to 07:00 the next day)

    Design Problem:
    What relays can I use that can be actuated by logic voltages?
    Should I use 2 relays, a logic relay that actuates a power relay?
    What relay can I use that can handle continuous amp draw of 8 machines and 8 start up amp draws?

    Theory:
    Digital Logic timer to send a shut down sequence to each of the 4 relays (2 plugs x 4 receptacles)
    Relays (SPST-NC latching) or (SPST-NO)

    Also, a feasibility study of anyone who has either done this before or done something similar or has any insight to anything I should be aware of.

    Thanks
     
  2. jcsd
  3. Jul 9, 2013 #2

    dlgoff

    User Avatar
    Science Advisor
    Gold Member

  4. Jul 9, 2013 #3
    Thanks! I will look into this.
     
  5. Jul 9, 2013 #4
    for the quantity of devices you would like to power off another inexpensive option is a smart relay controller. Such as the Pico smart relay controller from Allen Bradley. They have a real time clock, include software and programming cable.

    The programming would need some knowledge of ladder logic, however for your application its an easy program that I can help you with. Would only take me 1/2 hour lol.

    http://literature.rockwellautomation.com/idc/groups/literature/documents/pp/1760-pp001_-en-p.pdf [Broken]

    I found that if you need a timer and more than 4 relays this option often comes out cheaper.

    the 240 volt may be a problem with the above option I know they have 120 output not sure on the 240 volt output
     
    Last edited by a moderator: May 6, 2017
  6. Jul 10, 2013 #5
    That's great, the logic is pretty much the same as digital logic 'cept with different symbols, I could read up on the code syntax as well. I will follow up through this line of these controllers to see if I can find some that can handle 30 amps; I'm looking through the brochure the contacts seem a little small.
     
  7. Jul 10, 2013 #6
    they are good controllers, I looked over the product line the relays in them are too low in amperage to run the 30 amps through them. What can be done however is to use the RTC of the controller to control the outputs of 30 amp contact blocks with your 30 amp circuits on those contacts.
     
  8. Jul 10, 2013 #7

    dlgoff

    User Avatar
    Science Advisor
    Gold Member

    Last edited by a moderator: May 6, 2017
  9. Jul 10, 2013 #8
    that is a better option with greater flexibility on the RTC application as opposed to the smart relays
     
  10. Jul 12, 2013 #9
    Thanks alot guys, these are all very interesting ways for me to implement a solution. The last one seems to be the most straightforward. I'll let you know how it goes!
     
  11. Jul 12, 2013 #10
    The Intermatic and a GE version are available in the big box - Lowes/HD - they are used frequently for pools.
     
Know someone interested in this topic? Share this thread via Reddit, Google+, Twitter, or Facebook




Similar Discussions: 120-240VAC Digital Logic Power Relay Timer
Loading...