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

Also see for AquaEdge 19XR series: Installation instructions Start-up, operation and maintenance instructions

Contents

57Checking Pressure TransducersThere are 4 typically factory-installed pressure transducers mea-suring refrigerant and oil pressure and, if equipped, a fifth pressuretransducer measuring economizer pressure.These transducers can be calibrated if necessary. It is necessary tocalibrate at initial start-up, particularly at high altitude locations, toensure the proper refrigerant temperature/pressure relationship.Each transducer is supplied with 5 vdc power. If the power supplyfails, a transducer voltage reference alarm occurs. If the transducerreading is suspected of being faulty, check the TRANSDUCERVOLTAGE REF supply voltage. It should be 5 vdc ± 0.5 v as dis-played in MAINTENANCE MENU MAINTENANCEOTHERS, where all the transducer voltages are shown. If theTRANSDUCER VOLTAGE REF supply voltage is correct, thetransducer should be recalibrated or replaced.Also check that inputs have not been grounded.PRESSURE TRANSDUCER REPLACEMENTSince the transducers are mounted on Schrader-type fittings, thereis no need to remove refrigerant from the vessel when replacingthe transducers. Disconnect the transducer wiring. Do not pull onthe transducer wires. Unscrew the transducer from the Schraderfitting. When installing a new transducer, do not use pipe sealer(which can plug the sensor). Put the plug connector back on thesensor and snap into place. Check for refrigerant leaks.COOLER AND CONDENSER PRESSURE TRANSDUCERCALIBRATIONCalibration can be checked by comparing the pressure readingsfrom the transducer to an accurate refrigeration gage reading.These readings can be viewed or calibrated from the HMI screen.The transducer can be checked and calibrated at 2 pressure points.These calibration points are 0 psig (0 kPa) and between 25 and250 psig (173 and 1724 kPa). Wiring is shown in Fig. 57. Installa-tion of pressure transducers into water nozzles using flushable dirtleg trap is suggested; see Fig. 58. Connect pressure transducer toSchrader connection. To enable this option, IOB4 must be activat-ed and the Option must be selected in the Option Configurationmenu. To calibrate these transducers:1. Shut down the compressor, cooler, and condenser pumps.NOTE: There should be no flow through the heat exchangers.2. Disconnect the transducer in question from its Schraderfitting for cooler or condenser transducer calibration. Foroil pressure or flow device calibration, leave the trans-ducer in place.NOTE: If the cooler or condenser vessels are at 0 psig(0 kPa) or are open to atmospheric pressure, the transduc-ers can be calibrated for zero without removing the trans-ducer from the vessel.3. Access the PRESSURE or HYDRAULIC STATUS screenand view the particular transducer reading. To calibrate oilpressure or waterside flow device, view the particularreading. It should read 0 psig (0 kPa). If the reading is not0 psig (0 kPa), but within ± 5 psig (35 kPa), the value maybe set to zero from the Maintenance Menu while theappropriate transducer parameter is highlighted. The valuewill now go to zero.If the transducer value is not within the calibration range,the transducer returns to the original reading. If the pres-sure is within the allowed range (noted above), check thevoltage ratio of the transducer. To obtain the voltageratio, divide the voltage (dc) input from the transducer bythe supply voltage signal or measure across the positive(+ red) and negative (– black) leads of the transducer.The input to reference voltage ratio must be between0.80 and 0.11 for the software to allow calibration.Rotate the waterside flow pressure device from the inletnozzle to the outlet nozzle and repeat this step. If rotatingthe waterside flow device does not allow calibration,pressurize the transducer until the ratio is within range.Then attempt calibration again.4. Pressures can be calibrated between 100 and 250 psig(689.5 and 1723.7 kPa) by attaching a regulated 250 psig(1724 kPa) pressure (usually from a nitrogen cylinder).For calibration, access the Pressure Sensor CalibrationMenu from the Maintenance Menu and calibrate theappropriate sensor.The PIC 6 control system does not allow calibration if the trans-ducer is too far out of calibration. In this case, a new transducermust be installed and re-calibrated. If calibration problems are en-countered on the OIL PRESSURE DELTA P channel, sometimesswapping the compressor oil discharge pressure transducer andthe oil sump pressure transducer will offset an adverse transducertolerance stack up and allow the calibration to proceed.HYDRAULIC STATUSThe HYDRAULIC STATUS screen (access from the Main Menu)provides a convenient way to detect if any of the cooler/condenserpressure switches (if installed) are in need of calibration. With noflow and no added resistors the water delta should read zero psig(0 kPa). If it does not, the value may be set to zero using PRES-SURE SENSOR CALIB located in the Maintenance Menu.High Altitude LocationsBecause the chiller is initially calibrated at sea level, it is necessaryto recalibrate the pressure transducers if the chiller has beenmoved to a high altitude location. See the calibration procedure inthe 19XR with PIC 6 Controls Operation and Troubleshootingguide. Note that Atmospheric Pressure can be adjusted in the Ser-vice Parameters Menu (located in the Configuration Menu).Quick TestThe Quick Test feature is located in the Main Menu. Use thisfeature to test guide vanes, test chiller status, test the status ofvarious actuators, view water temperature deltas, and test oilpump and oil heater relays, as well as control inlet guide vane,hot gas bypass, economizer damper, alarms, condenser, andchilled water pumps. The tests can help to determine whether aswitch is defective or a pump relay is not operating, as well asother useful troubleshooting issues. During pumpdown opera-tions, the pumps are energized to prevent freeze-up and the ves-sel pressures and temperatures are displayed. Note that prior toQuick Test, components with feedback needs to be calibrated inQuick Calibration.Pumpdown/LockoutThe Pumpdown/Lockout feature, available from the MaintenanceMenu, prevents compressor start-up when there is no refrigerant inthe chiller or if the vessels are isolated. The Terminate Lockoutfeature ends the Pumpdown/Lockout after the pumpdown proce-dure is reversed and refrigerant is added.Physical DataTables 14-44 and Fig. 59-76 provide additional information oncomponent weights, compressor fits and clearances, physical andelectrical data, and wiring schematics for the operator’s conve-nience during troubleshooting.WARNINGBe sure to use a back-up wrench on the Schrader fitting when-ever removing a transducer, since the Schrader fitting mayback out with the transducer, causing a large leak and possibleinjury to personnel.