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  1. #1
    Join Date
    Apr 2008
    Posts
    9

    Question Cooling Compressor Pressure Sensors

    I have an odd problem any thoughts would be appreciated.

    I have a set of screw compressors that have suction and discharge ports on the lines with a PV09AV Veris (0-10V) pressure sensor.

    The pressure sensors are setup properly and I have used them many times before. The sensors on the suction side read a negative voltage when the screw compressors activate.

    Anyone have any thoughts on why this would happen, the sensors are 0-10 volts and should not output a negative voltage however when I metered them I read -1.5 volts. The common to the sensors are grounded to the building steel along with the copper refrigerant lines.

  2. #2
    Join Date
    Jun 2010
    Location
    S. Texas
    Posts
    63
    I would try floating the ground and taking a reading. Could easily be something coming from the grounding.

  3. #3
    Join Date
    Aug 2006
    Location
    Central Indiana
    Posts
    212

    Wink Floating is best

    Quote Originally Posted by snowbertca View Post
    I would try floating the ground and taking a reading. Could easily be something coming from the grounding.
    I have always floated ALL inputs. NEVER take to chassis or electrical ground.
    Thanks. Mike

  4. #4
    Join Date
    Apr 2007
    Location
    Amarillo by mornin'
    Posts
    851
    Quote Originally Posted by JNorton View Post
    The sensors on the suction side read a negative voltage when the screw compressors activate.
    Are you able to read the actual pressure with it running? The pressure probably is in a negative/vacuum. I've seen several chillers run in a negative pressure on the suction side.
    "It's not that I'm smart, it's that I stay with the problem longer”
    Albert Einstein

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