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Thread: Too far to trip relay??

  1. #1
    Join Date
    May 2017
    Location
    Phoenix
    Posts
    2

    Too far to trip relay??

    Gentlemen...I just registered and my last question was answered so wonderfully I am beginning to have more trust in this forum than my coworkers.

    Here's the question: I have an air compressor that has a control panel as part of it. The compressor control panel has pins to turn it on, tell you if its running etc, there is also a 24vdc to "wet" the contacts. I want to interface this air compressor with a VFD about 6-700 feet away. I have a pump that I want to turn on at the same time as the Air compressor, and I show a control panel near my pump ( and 600') from my air compressor. This control panel via a relay contact closes the pins to the air compressor and pump at the same time via a 120v relay.

    Does the 120v relay simply close each contact for the pump and air compressor and will I have to apply a 24VDC source to the compressor and the pump ( the pump run signal is given via a VFD, so really im closing the VFD run contacts)

    I think I can close the air compressor contacts fine with a relay and then apply a 24vdc to the air compressor start pin, but what about a signal back from the compressor that says its running?

    I am good enough to be dangerous with this stuff hahaha, thank you!

    Here is a picture showing the start/stop pin and a 24vdc next to it....so just connect the two and place my relay contacts n between them for control??

    Name:  Compressor Contacts.PNG
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  2. #2
    Join Date
    Jun 2006
    Location
    Ohio
    Posts
    20,836
    Not enough info. Need bigger if not complete picture.

    Got links to any equipment?
    I will have achieved my life's goal if I die with a smile on my face.

  3. #3
    Join Date
    Jan 2016
    Location
    PA
    Posts
    3,460
    Confusing

    you need to start 2 machines
    a compressor w/starter cntl pnl
    a pump w/vfd

    what starts the compressor?
    low pressure?
    manuall?

    the pump
    sounds like you want it interlocked with the comp
    when the comp starts the pump starts

    need the control pnl and vfd dwgs



  4. #4
    Join Date
    Oct 2008
    Location
    Nebraska
    Posts
    429
    Quote Originally Posted by Honeycone View Post
    I am beginning to have more trust in this forum than my coworkers.
    Almost always. There are exceptions to this but for the most part you will find no egos here. Most members just want things to be done right.
    Deserve's got nothin' to do with it.

  5. #5
    Join Date
    Feb 2016
    Location
    Illinois
    Posts
    272
    "....has pins to tell you it is running...."

    Can you be more specific? Likely you can use the signal to start the pump, but in order to be more helpful, we need more info.

  6. #6
    Join Date
    Dec 2007
    Location
    NE Nebraska
    Posts
    32,543
    Quote Originally Posted by retirede View Post
    "....has pins to tell you it is running...."

    Can you be more specific? Likely you can use the signal to start the pump, but in order to be more helpful, we need more info.
    My best guess is that means there is terminals connected to an aux contact that changes state when the drive is "running", or possibly even a digital or analog output that changes state when "running". The limitiation is that it tells you there is an active run output, but may not tell you if the compressor is actually "compressing". Motor to compressor coupling issues, or mechanical failure within compressor could leave you with motor running but no pressure being developed - if you want to detect that situatiuon, a pressure switch is maybe the way to prove what you want before starting the other pump.

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