Using a timer to switch air compressor on and off

Discussion in 'Power Electronics' started by MRENIGMA, Jul 13, 2017.

  1. MRENIGMA

    Thread Starter New Member

    Jul 13, 2017
    10
    0
    Hi

    I want to switch an air compressor off from a timer that i have attached the link that i will be using. The compressor is a 3 phase star delta unit and i have attached schematic for it. My question is do i simply put the timer between the coil of the contactor KM1 and use the output of the timer to switch the coil on it or do i have to put it elsewhere in the circuit seeing as it is star delta? The current set up has no timer on it it just has a direct start and stop on it on the front panel on an LCD panel.

    http://ie.rs-online.com/web/p/products/8347530/ timeclock
     
  2. profbuxton

    Member

    Feb 21, 2014
    352
    161
    Is the start stop a touch button on the LCD Screen? I cannot see on your schematic where the stop start buttons are?
     
  3. MRENIGMA

    Thread Starter New Member

    Jul 13, 2017
    10
    0
    Hi Prof

    Yes they are. I have attached images for reference
     
  4. profbuxton

    Member

    Feb 21, 2014
    352
    161
    I can not see how you connect a timer into this system since the start stop control is via the LCD screen. I assume that device controlling this is some sort of PLC with a screen and it controls the starting in Star/ Delta with some sort of program. About the only thing you could do is to start the timer with KM1 and when it times out it would open the emergency stop line. But you would still need to push the start button on screen to start .
    Is the contact on terminal 19 a remote start? If it is then maybe that could be used to timer start the cycle?
     
  5. MRENIGMA

    Thread Starter New Member

    Jul 13, 2017
    10
    0
    It is being controlled by the controller from the second image in the previous message i sent that is its schematic. it looks like the jumper on terminal 19 is a remote start but the compressor is running non stop so i cant be sure until i can test it. the type of clock i am installing has a relay output so i was thinking if i use the output on the timer to turn on KM1 this would work as everything else is direct on line starting with the star delta
     
  6. MaxHeadRoom

    Expert

    Jul 18, 2013
    16,395
    4,825
    Why not replace the PLC input that initiates the start with the output of the timer? AFA I can see you would not use the coil of KM1, this is by passing the controller output.
    Max.
     
    strantor likes this.
  7. profbuxton

    Member

    Feb 21, 2014
    352
    161
    I don't think just turning on KM1 would work as you need the controller to switch the comp. from Delta to Star at the correct time or load.
    I would try the "remote' switch on terminal 19 and see if it starts and stops the machine when operated.
    Not sure how you intend to use the timer. How do you want to start the time delay to start and what will reset the timer when timed out.
    Had a second close look at what you want to do. You only want to switch comp off after time delay.
    Easy. Connect timer coil(timer start) across KM1.Connect timer contact(n/c) in series with emergency contact. When comp starts timer will start, time out and operate emergency stop.When comp stops, timer will be reset for next time. May also be able to use the remote start/stop if that works(preferable).
     
  8. MRENIGMA

    Thread Starter New Member

    Jul 13, 2017
    10
    0
    Hi Max

    This is not a PLC per se it is more of a contoller on off start stop so im not sure what exactly you mean
     
  9. MaxHeadRoom

    Expert

    Jul 18, 2013
    16,395
    4,825
    If not a PLC what type of controller is It?
    It appears to be some logic controller of some sort.
    Do you have a link to the manf.?
    Max.
     
  10. MRENIGMA

    Thread Starter New Member

    Jul 13, 2017
    10
    0
  11. MaxHeadRoom

    Expert

    Jul 18, 2013
    16,395
    4,825
    It is a form of PLC, seems like an automotive application?
    What is it doing in a star-delta starter application?
    I imagine there is a timer in there to control the star to delta transfer delay.
    Max.
     
  12. MRENIGMA

    Thread Starter New Member

    Jul 13, 2017
    10
    0
    it is turning on an air compressor for a compressed air in a plant
     
  13. siraziazad

    New Member

    Jan 8, 2018
    1
    0
    This is very technical issue . If your are not well informed, go to a technicians
     
  14. WBahn

    Moderator

    Mar 31, 2012
    23,179
    6,978
    One thing to be sure of is that, however you tackle this, that the compressor head gets unloaded after it is shut down and before it is restarted. Most likely whatever changes you make will not interfere with this process and you'll be fine. Just make sure that you don't inadvertently bypass this process and prevent the head from unloading.
     
  15. tcmtech

    Distinguished Member

    Nov 4, 2013
    2,809
    2,703

    It looks like the #18 input is for remote on/off override of the system which if so that's where the timer contacts would be tied in.
     
Loading...