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Christopher Moya Wednesday, October 11, 2017 by Christopher Moya

How to test a coil with a digital multimeter?

When it comes to solenoid valves in the industrial hydraulic, pneumatic, and processing world it contains a coil. My question what is the correct way to test the coil? I was told if you put the setting of your digial multi-meter to the ohms setting and place it across the two terminals that you should get an ohm reading which indicated that the coil is good. If you test a coil and you get an OL reading then that means that you have a defected coil and you need to replace it with a new one. Is this the correct way to test a coil? If not then what is the best way to test a coil to a solenoid to a valve?



Comments

  • by  Kevin Angelo Ma (edited)
    I think that steps your are referring is this "one("")":https://www.youtube.com/watch?v=LTjx3VIXOu0?
  • by  Aubrey Kagan (edited)
    Yes using a DMM configured for ohms is one way to check the coil on a solenoid/relay coil. Please note the the coil must be disconnected from the circuit or you may get undesired results including destroying your DMM if your coil is powered. There are other ways. With the solenoid in circuit and powered up, but with the coil inactive, you should be measure the same voltage on both sides of the coil (note if the coil is AC powered, the DMM should obviously set to AC Volts) relative to the circuit common. If not, the coil is open. A third way is to set your DMM to measure current (AC current if the coil is AC powered). Then insert the DMM in series with the supply to or return from the coil. When the coil is activated you should see a current. If not the coil is open circuit. This test is useful in deciding whether the contacts or the coil are faulty.
    • by  Aubrey Kagan (edited)
      I should mention that in both the second and third examples where there may be some leakage which may mean you have to think about the observed results- for instance if you are using capacitive snubbers with AC voltages, it may appear that there is a voltage drop across the coil, but at a low current.
  • by  Aubrey Kagan (edited)
    I should mention that in both the second and third examples where there may be some leakage which may mean you have to think about the observed results- for instance if you are using capacitive snubbers with AC voltages, it may appear that there is a voltage drop across the coil, but at a low current.
  • by  Gustavo Cedron

    to test the coil: digial multi-meter. Find your option:

    http://www.amperis.com/en/

  • by  Dishan Pangan

    I believe the standard terminal markings for contactor coils are A1 and A2. Set your DMM as an Ohmmeter, place the test leads across A1 and A2. If the reading is 50 Ohms or below, the coil is still functioning well, but if you get hundreds of Ohms or an "OL" reading, then the coil could not hold its contacts anymore, meaning busted.

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