Carrier 19XRV Start-up, Operation And Maintenance Instructions Manual

Also see for AquaEdge 19XRV series: Start-up and service instructions Installation instructions Start-up, operation and maintenance instructions Start-up and service instructions User manual

Carrier 19XRV Start-up, Operation And Maintenance Instructions Manual Manual pdf 43 page image

thecontrol'smodelof thesurgepreventionlineup.Guidevanesarenotpermittedtoopenfurtherwhensurgepreventionison.Oncespeedhasbeenincreasedtomaximum,if stilloper-atinginthesurgepreventionregionandif theHotGasBypassoptionisinstalled,thehotgasbypassvalvewill open.WheninSurgePreventionmode,withacommandtodecreasecapacitytheguidevaneswillclosebutspeedwillnotdecrease.NOTE:If uponromp-upa chillerwithVFDtendstogotofullspeedbeforeguidevanesopenfully,that is an indication thatthe lift at low load is excessive, and the operating point moveddirectly into the surge prevention region. In this case, investi-gate the ability of the condenser cooling means (e.g., coolingtower) to provide cooling water in accor&mce with the designload/entering condenser water temperature schedule.A surge condition occm:s when the lift becomes so high thegas flow across the impeller reverses. This condition caneventu_dly cause chiller damage. When enabled, the SurgePrevention Algorithm will adjust either the ACTUAL GUIDEVANE POSITION or ACTUAL VFD SPEED to maintain thecomplessor at a safe distance from surge while maintainingmachine efficiency. If the surge condition degrades then thealgorithm will move aggressively away from surge. Thiscondition can be identified when the SURGE/H(;BP ACTIVE?on the HEAT EX display screen displays a YES.The surge prevention algorithm first determines if correc-tive action is necessary. The algorithm checks two sets ofoperator-configured data points, the lower stage point (MIN.LOAD POINT [T1,P1]) and the upper surge point (FULLLOAD POINT [T2,P2]). The surge characteristics varybetween different chiller configurations and operatingconditions.The surge prevention algorithm function and settings aregraphically displayed on Fig. 22 and 23. The two sets of loadpoints on the graph (default settings m'e shown) describe aline the algorithm uses to determine the maximum lift ofthe compressor for the design maximum operating speed.When the actual differential pressme between the cooler andcondenser (delta P) and the temperature difference between theentering and leaving chilled water (delta T) are above the lineon the graph (as defined by the MIN LOAD POINTS and FULLLOAD POINTS), the algorithm operates in Surge Preventionmode. This is determined when the ACTIVE DELTA T is lessthan SURGE/HGBP DELTA T minus the SURGE/HGBPDEADBAND.When in Surge Prevention mode, with a command toincrease capacity, the VFD speed will increase until VFDMAXIMUM SPEED is reached. At VFD MAXIMUM SPEED,when Capacity still needs to increase, the IGV's open. When inSurge Plevention mode, with a command to decrease capacity,the IGVs will close. The optional hot gas bypass will open insurge prevention mode only if the TARGET VFD SPEED is atthe VFD MAXIMUM SPEED.Surge Protection -- The PIC III monitors surge, whichis detected as a fluctuation in compressor motor amperage.Each time the fluctuation exceeds an operator-specified limit,the PIC III registers a stage protection count. The currentfluctuation threshold that triggers a surge protection count isequal to the sum of SURGE DELTA % AMPS plus theCHILLED WATER DELTA T. If more than 5 surges occurwithin an operator-specified time (SURGE TIME PERIOD),the PIC III initiates a surge protection shutdown of the chillecThe SURGE PROTECTION COUNTS remain displayed in theCOMPRESS screen until the almm is reset, at which time theyare re-zeroed.If a surge count is registered and if ACTUAL VFD SPEEDis less than VFD MAXIMUM SPEED then motor speed will beincreased by the configured VFD INCREASE STER Whilethe SURGE PROTECTION COUNTS are >0, a speed decreasewill not be honored.The portion of the surge count threshold attributable to cur-rent can be adjusted from the OPTIONS screen (see Table 4).Scroll down to the SURGE DELTA % AMPS parameter, anduse the [INCREASE] or [DECREASE] softkey to adjust thepercent current fluctuation. The default setting is 10% amps.The SURGE TIME PERIOD can also be adjusted from theOPTIONS soeen. Scroll to the SURGE TIME PERIODparameter, and use the [INCREASE] or [DECREASE]softkeyto adjust the amount of time. The default setting is 8 minutes.Access the display soeen (COMPRESS) to monitor thesurge count (SURGE PROTECTION COUNTS).19XRV DEFAULTS:ATt = 1.5= FAP1 = 50 psidAT2 = llY" FAP2 = 85 psid_p(psi)85-50-HGBP/SURGE PREVENTION (lo, 85)ONDEADBAND REGION ,1 2 3 4 5 6 7 8 9 10 1 1AT (F)LEGENDECW -- Entering Chilled WaterHGBP -- Hot Gas BypassLOW -- Leaving Chilled WaterAP = (Condenser Psi) -(Cooler Psi)AT = (ECW) - (LCW)Fig. 22-- 19XRV Not Gas Bypass/SurgePrevention with Default English Settingszxp(kPa)19XRV DEFAULTS: AT1 =.8° CAPt = 345 kPadAT2 = 5.6° CAP2 = 586 kPadHGBP/SURGE PREVENTION (&6, 586)ONDEADBAND REGION500-400-300-.2 A .6 .81,0 2.0 3.0 4.0 5.0 6.0&T (C)LEGENDECW -- Entering Chilled WaterRGBP -- Hot Gas BypassLOW -- Leaving Chilled WaterAP = (Condenser kPa) - (Cooler kPa)AT = (ECW) - (LCW)Fig. 23 i 19XRV Hot Gas Bypass/SurgePrevention with Default Metric Settings43