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Inductive load on relays

Discussion in 'General Electronics Discussion' started by dssokhey, Sep 8, 2017.

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  1. dssokhey

    dssokhey

    2
    0
    Sep 8, 2017
    Hi everybody. I am new to this forum, and an electronic hobbyist. working on a project that involves a DC 24 volt motor that is switched thru 2 relays, via 2 switching transistors, for to and fro motion. The relays are switched by a separate 12v dc supply. Direction control is thru 2 limit switches in a way that once the motor has moved in one direction, it hits the limit switch and it reverses direction till it hits the other limit switch and reverses direction again. And the 24 v dc supply to the motor comes thru a PWM motor speed controller.
    The problem that I am facing is: If the motor is NOT connected, the relays work fine. However, as soon as the motor is connected, the relays start chattering when the limit switch is pressed and most of the time do not work to reverse the direction of the motor. The relay coils do have 1N4001 diodes in reverse. I have tried placing a RC snubber across the motor terminals which helps, but practically voids the speed control. For example, if the voltage at motor terminals is 6 volts, as reduced by the speed controller, the snubber raises it to 20 volts. The speed controller does not affect the relay "chattering". I have confirmed that by eliminating if from the circuit.
    Any help to solve this problem will be highly appreciated.
    Thanks
     
  2. Minder

    Minder

    3,019
    640
    Apr 24, 2015
    Can you post the schematic of your set up, including power supply details?
    It sounds a little like your power is collapsing maybe when the motors are on line?
    The snubber is raising the voltage??
    M.
     
  3. kellys_eye

    kellys_eye

    4,275
    1,146
    Jun 25, 2010
    Are the 12/24V supplies on a common ground circuit? Do they need to be?
     
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