Carrier AquaEdge 19XR Start-up, Operation And Maintenance Instructions Manual

Also see for AquaEdge 19XR: Controls operation and troubleshooting Start-up, operation and maintenance instructions Start-up, operation and maintenance instructions

Carrier AquaEdge 19XR Start-up, Operation And Maintenance Instructions Manual Manual pdf 11 page image

11CONTROLSDefinitionsANALOG SIGNALAn analog signal varies in proportion to the monitored source. Itquantifies values between operating limits. (Example: A tem-perature sensor is an analog device because its resistance chang-es in proportion to the temperature, generating many values.)DISCRETE SIGNALA discrete signal is a 2-position representation of the value of amonitored source. (Example: A switch produces a discrete signalindicating whether a value is above or below a set point or bound-ary by generating an on/off, high/low, or open/closed signal.)GeneralThe 19XR centrifugal liquid chiller contains a microprocessor-based control center that monitors and controls all operationsof the chiller. The microprocessor control system matches thecooling capacity of the chiller to the cooling load while provid-ing state-of-the-art chiller protection. The system controlscooling load within the set point plus the deadband by sensingthe leaving chilled water or brine temperature and regulatingthe inlet guide vane via a mechanically linked actuator motor.The guide vane is a variable flow pre-whirl assembly that con-trols the refrigeration effect in the cooler by regulating theamount of refrigerant vapor flow into the compressor. An in-crease in guide vane opening increases capacity. A decrease inguide vane opening decreases capacity. The microprocessor-based control center protects the chiller by monitoring the digi-tal and analog inputs and executing capacity overrides or safetyshutdowns, if required.PIC 5 System ComponentsThe chiller control system is called the PIC 5 (Product IntegratedControl 5). See Table 1. As with previous PIC versions, the PIC5 system controls the operation of the chiller by monitoring alloperating conditions. The PIC 5 control system can diagnose aproblem and let the operator know what the problem is and whatto check. It promptly positions the guide vanes to maintain leav-ing chilled water temperature. It can interface with auxiliaryequipment such as pumps and cooling tower fans to turn them onwhen required. It continually checks all safeties to prevent anyunsafe operating condition. It also regulates the oil heater whilethe compressor is off and regulates the hot gas bypass valve, ifinstalled. The PIC 5 controls provide critical protection for thecompressor motor and control the motor starter.Table 1 — Major PIC 5 Components andPanel LocationsNOTE: For detailed information about the PIC 5 HMI (humanmachine interface), see the 19XR with PIC 5 Controls Opera-tion and Troubleshooting manual.START-UP/SHUTDOWN/RECYCLE SEQUENCELocal Start/Stop ControlLocal start-up (or manual start-up) is initiated by pressing thegray Start/Stop icon on the HMI interface. See Fig. 6.This initiates the PIC 5 starting sequence by displaying the list ofoperating modes. Press Local On to initiate start-up. See Fig. 7.NOTE: Prior to start-up, the start-to-start timer and the stop-to-start timer must have elapsed and all alarms must be cleared(see Troubleshooting Guide section on page 43).When start-up is initiated the status screen displays the start-upprogress and the Start/Stop icon blinks green. Once localstart-up begins, the PIC 5 control system performs a series ofpre-start tests to verify that all pre-start alerts and safeties arewithin acceptable limits. Table 2 shows appropriate PrestartAlerts/Alarms conditions. If a test is not successful, the start-upis delayed or aborted. If the tests are successful, the start-upwill be in progress and the COMPRESSOR RUN STATUSshall be “Startup.” The control shall then energize the chilledwater/brine pump relay.Five seconds later, the condenser pump relay energizes. Thirtyseconds later the PIC 5 control system monitors the chilled waterand condenser water flow devices and waits until the WATERFLOW VERIFY TIME (operator-configured, default 5 minutes)expires to confirm flow. After flow is verified, the chilled watertemperature is compared to CONTROL POINT plus 1/2CHILLED WATER DEADBAND. If the temperature is less thanor equal to this value, the PIC 5 control system turns off the con-denser pump relay and goes into a Recycle mode.If the water/brine temperature is high enough, the start-up se-quence continues and checks the guide vane position. If theguide vanes are more than 4% open, the start-up waits until thePIC 5 COMPONENT PANEL LOCATIONChiller Human Machine Interface (HMI) andDisplayHMI Control PanelIntegrated Starter Module (ISM) Starter CabinetChiller IO Boards Control PanelOil Heater Contactor (1C) Control PanelOil Pump Contactor (2C) Control PanelHot Gas Bypass Relays (HCLR, HOPR)(Optional)Control PanelControl Transformers (T1, T2, T3) Control PanelTemperature Sensors See Fig. 2 and Fig. 5Pressure Transducers See Fig. 2 and Fig. 5Fig. 6 — Chiller Start/Stop IconUnit Start/StopFig. 7 — Local On