PUMP can effect to main circuit breaker get trip?

Discussion in 'Pumps and Tanks Well Forum & Blog' started by chomnap, Dec 3, 2008.

  1. chomnap

    chomnap New Member

    We have 3 chillers, 3 CHWP and 3 CDWP dedicated for office tower building load.

    Chiller technical room is at roof floor.

    When we run all CDWP, it is fine.

    If we start running one CHWP, that is fine also.

    But if we run 2 CHWP, one CHWP will make main circuit breaker get trip.

    Note: breaker calibration is 150%[160A] higher than normal rated Amp.
    - Cable line to each pump is fine, around 30 or 38 DegC
    - During Breaker get trip, max rated Amp=80A
    - CHWP- Chilled Water Pump
    - CDWP- Condenser Water Pump

    Could you kindly advice?
    Does the pump motor get problem?
    Does the alignment pump get problem?
    Does the surge pressure head can effect to motor overload?

    Very thanks for your advice and comment.

  2. Cass

    Cass Plumber

    Were you able in the past to do this and all of a sudden you no longer can or is this all a new install.
  3. Pump Man

    Pump Man Junior Member

    Auburn WA
    To do some troubleshooting we need to know what the load amps are on the motors. I would also recommend having a amp probe on the breaker to measure the amps when starting each motor.
  4. chomnap

    chomnap New Member

    Hi Pump man,
    The rated Amp of motor are 103A.
    Note: Pump motor is equiped with VSD.
    MCB reated 150A {GV7-RE150}.

    Kindly let me know your idea?

    Very thanks for your help......

    Enjoy your day!
  5. chomnap

    chomnap New Member

    Hi Cass,
    This site is new building installation.
    we face this problem during Testing and Commissioning period.

    Note: We used existing chiller with New Chilled Water Pump.
    the problem is chilled water pump MCB GV7-RE150 is always trip even start-up and stop.

    Thanks for your help.

  6. valveman

    valveman Moderator Staff Member

    Lubbock, Texas
    These kind of problems are nearly always caused by the VSD. You probably do not have the correct shielded cable, or the grounding in not adequate. It could also be the combined harmonics from the two pumps. Harmonics cause "dirty power" to go back into the electric grid. This increases amperage and heat in the breakers and transformers.

    VSD's are suppose to save energy but, they don't. Usually the VSD is such short lived, causes so many problems, and cost so much to maintain or replace, that you can never save enough energy to justify the cost of the VSD. Sizing the pump correctly and using a simple valve for flow control can save just as much energy, last much longer, cost less, and doesn't give the problems associated with VSD control.
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