Is this Relay Logic diagram correct?

Discussion in 'Homework Help' started by Daniel718, Dec 27, 2014.

  1. Daniel718

    Thread Starter New Member

    Dec 27, 2014
    Hello, i am trying to get a better understanding on relay logic. i just got my foot in the elevator field and noticed plc's are widely used. i created a scenario and solved it using relay logic. i would like your input to see if you can find any problems with this diagram. Thank you.

    Create a 2 floor lift that has the following:
    1.Hall stop switch
    2.Top and bottom final limits (TF & BF) (used to stop the lift level to door zone)
    3.Door locks (DL) ( Hall door interlock//Lift cannot move unless DL contacts are made)
    4.Gate Switch (GS) ( Lift door interlock//Lift cannot move unless GS contacts are made)

    -Gate switch,Door locks and Stop switch are considered safeties. if any of the safeties are open the lift will not move.
    -Lifts are not passenger cars, so there will be no personnel in the lift( meaning no inputs are required inside)

    My question: Do you notice a problem? Any suggestions on how to better improve this scenario/diagram?

    jahangir_has likes this.
  2. MaxHeadRoom


    Jul 18, 2013
    Looks reasonable to me, It is usual to fit the motor overload detection contacts in the 1CR and 2CR strings.
    The stop button would need to be push to latch - turn to release, not momentary.
    A master control relay would be better maybe.
    See PDF.
  3. jahangir_has

    New Member

    Apr 12, 2015
    and what about speed slow system? and how we slow the lift can u draw another drawing, kindly.