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Recent content by psighi

  1. psighi

    T-8 ballast vs. occupancy sensor

    Has any one experience high failure rates of electronic ballasts when operating them on an occupancy sensor? I've been losing ballasts quite frequently since their install about 6 months ago. I am curious about the effects of the inrush current and cycling multiple turn-on's/off's?
  2. psighi

    Electrical Room Ventilation

    If the system was installed in the 70's or early 80's, and changes to the facility may have increased the heat gain from the panels and xfmr's, consider the effects of switching power supplies causing odd-order harmonics and neutral currents.
  3. psighi

    Cooling Tower VFD energy savings

    Consider a 2-speed, single winding motor. Manufactures claim at low speed (50% rpm), the tower is 60% of rated capacity. Running the fan at ~80% speed, will yield approximately 50%bhp. The sacrifice, for those who look at the big pix, is CWS temperature rises. For every degree of CWS...
  4. psighi

    BMS reading for chiller

    If the system is sophisticated enough to have a BACnet interface with the chiller, the chiller will provide for a tonnage variable from the chiller panel. If you are observing the remote temperature and flow meter sensors in your EMCS, that calculation will be based on the EMCS sensors and you...
  5. psighi

    VSD Centrifugal Chillers

    The vfd chillers were considered because of load diversity from day to night (24-hour operation). If you compare the IPLV's of the vfd vs. non-vfd chillers the efficiencies are quite significant. The efficieny curves go much lower at partial loads and stays lower down to 20% capacity...
  6. psighi

    sensor for control of cooling water temperature

    Enthalpy sensors. High maintenance and pricey. If the towers are controlled by vfd's or two speed controllers, provide a setpoint controller for the desired ecwt. Otherwise a management system is required with some nifty algorithms. I built one that provides fuzzy control of the setpoint that...
  7. psighi

    Optimum Condenser Water Temperatures

    From my experience as a former cooling tower representative and now design engineer, my attitude toward most A/C units is: the only true variable in optimization of efficiency is condenser condition. Lower the condensing temperature, the lower the lift and the more efficient the machine. That...
  8. psighi

    Looking for Industrial Oil Cooler

    Try Flatplate, if interested. They make good PHE's for this application.
  9. psighi

    Waste Heat Recovery system

    Try Cain Industries.
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