Carrier 19DV Series Installation, Operation And Maintenance Instructions

Also see for AquaEdge 19DV series: Start-up, operation and maintenance instructions Start-up, operation and maintenance instructions Installation instructions Controls operation and troubleshooting Operation and Troubleshooting

Contents

Carrier 19DV Series Installation, Operation And Maintenance Instructions Manual pdf 25 page image

252.6 – CONTROLS2.6.1 DefinitionsANALOG SIGNAL — An analog signal varies in proportion to the monitored source. It quantifies values betweenoperating limits. (Example: A temperature sensor is an analog device because its resistance changes in proportionto the temperature, generating many values.)DISCRETE SIGNAL — A discrete signal is a 2-position representation of the value of a monitored source.(Example: A switch produces a discrete signal indicating whether a value is above or below a set point orboundary by generating an on/off, high/low, or open/closed signal.)2.6.2 GeneralThe 19DV centrifugal liquid chiller contains a microprocessor-based control center that monitors and controls alloperations of the chiller. The microprocessor control system matches the cooling capacity of the chiller to thecooling load while providing state-of-the-art chiller protection.The system controls cooling load within the set point plus the deadband by sensing the leaving chilled water orbrine temperature and regulating the inlet guide vanes and compressor speed. The guide vane is a variable flowpre-whirl assembly that controls the refrigeration effect in the cooler by regulating the amount of refrigerant vaporflow into the compressor. An increase in guide vane opening increases capacity. A decrease in guide vaneopening decreases capacity. The microprocessor-based control centerprotects the chiller by monitoring the digital and analog inputs and executing capacity overrides or safetyshutdowns, if required. The variable frequency drive (VFD) allows compressor start-up and capacity control bymodulating the motor frequency based on the operation condition.2.6.3 PIC 5+ system componentsThe chiller control system is called the PIC5+ (Product Integrated Control 5).As with previous PIC versions, the PIC5+ system controls the operation of the chiller by monitoring all operatingconditions. The PIC5+ control system can diagnose a problem and let the operator know what the problem is andwhat to check. It positions the guide vanes and VFD speed to maintain leaving chilled water temperature. Itcontrols the refrigerant pump providing compressor bearing lubrication and can interface with auxiliary equipmentsuch as pumps and cooling tower fans to turn them on when required.It continually checks all safeties to prevent any unsafe operating condition. It regulates the envelope controlvalve for stabilized aerodynamic operation, if installed. The PIC5+ controls offer an operator trending function tohelp the operator monitor the chiller status more easily and for critical compressor motor protection. The PIC5+system provides open protocols to support the competitive BMS system and can be integrated into Carrier’sLifecycle System Management for remote monitoring and data management.