Operation Maintenance Water Cooled CenTraVac With CH530

GeneralInformationCooling CycleCVHE, CVHG, CVHFWhen in the cooling mode, liquidrefrigerant is distributed along thelength of the evaporator and sprayedthrough small holes in a distributor(i.e., running the entire length of theshell) to uniformly coat eachevaporator tube. Here, the liquidrefrigerant absorbs enough heat fromthe system water circulating throughthe evaporator tubes to vaporize.The gaseous refrigerant is thendrawn through the eliminators(which remove droplets of liquidrefrigerant from the gas) and firststage variable inlet guide vanes, andinto the first stage impeller.Note: Inlet guide vanes are designedto modulate the flow of gaseousrefrigerant to meet system capacityrequirements; they also prerotate thegas, allowing it to enter the impellerat an optimal angle that maximizesefficiency at all load conditions.CVHE, CVHG CompressorCompressed gas from the first-stageimpeller flows through the fixed,second-stage inlet vanes and into thesecond-stage impeller.Here, the refrigerant gas is againcompressed, and then dischargedthrough the third-stage variable guidevanes and into the third stageimpeller.condenser. Baffles within thecondenser shell distribute thecompressed refrigerant gas evenlyacross the condenser tube bundle.Cooling tower water circulatedthrough the condenser tubes absorbsheat from the refrigerant, causing it tocondense. The liquid refrigerant thenpasses through orifice plate ‘‘A’’ andinto the economizer.The economizer reduces the energyrequirements of the refrigerant cycleby eliminating the need to pass allgaseous refrigerant through threestages of compression. See Figure 3.Notice that some of the liquidrefrigerant flashes to a gas becauseof the pressure drop created by theorifice plates, thus further cooling theliquid refrigerant. This flash gas isthen drawn directly from the first(Chamber A) and second (ChamberB) stages of the economizer into thethird-and second-stage impellers ofthe compressor, respectively.All remaining liquid refrigerant flowsthrough another orifice plate ‘‘C’’ tothe evaporator.CVHF CompressorCompressed gas from the first-stageimpeller is discharged through thesecond-stage variable guide vanesand into the second-stage impeller.Here, the refrigerant gas is againcompressed, and then dischargedinto the condenser.Baffles within the condenser shelldistribute the compressed refrigerantgas evenly across the condensertube bundle. Cooling tower water,circulated through the condensertubes, absorbs heat from therefrigerant, causing it to condense.The liquid refrigerant then flows outof the bottom of the condenser,passing through an orifice plate andinto the economizer.The economizer reduces the energyrequirements of the refrigerant cycleby eliminating the need to pass allgaseous refrigerant through bothstages of compression. See Figure 6.Notice that some of the liquidrefrigerant flashes to a gas becauseof the pressure drop created by theorifice plate, thus further cooling theliquid refrigerant. This flash gas isthen drawn directly from theeconomizer into the second-stageimpellers of the compressor.All remaining liquid refrigerant flowsout of the economizer, passesthrough another orifice plate and intothe evaporator.Once the gas is compressed a thirdtime, it is discharged into the10CVHE-SVU01E-EN

GeneralInformationFigure 3. CVHE, CVHG pressure enthalpy curveFigure 4. CVHE, CVHG 2-stage economizerCVHE-SVU01E-EN11

GeneralInformationFigure 5. CVHF pressure enthalpy curveFigure 6. CVHF single stage economizer12CVHE-SVU01E-EN

GeneralInformationOverviewControls Operator InterfaceInformation is tailored to operators,service technicians and ownersWhen operating a chiller, there isspecific information you need on aday-to-day basis — setpoints, limits,diagnostic information, and reports.When servicing a chiller, you needdifferent information and a lot moreof it — historic and activediagnostics, configuration settings,and customizable control algorithms,as well as operation settings.DynaView Human Interface— For the operatorDay-to-day operational information ispresented at the panel. Up to sevenlines of data (English or SI units) aresimultaneously displayed on the ¼VGA touch-sensitive screen.Logically organized groups ofinformation — chiller modes ofoperation, active diagnostics,settings and reports put informationconveniently at your fingertips. SeeOperator Interface Section for details.By providing two different tools –one for daily operation and one forperiodic service — everyone haseasy access to pertinent andappropriate information.Figure 7. CVHE, CVHF, and CVHG sequence of operation overviewCVHE-SVU01E-ENTechView Chiller Service Tool— For the service technician oradvanced operatorAll chiller status, machineconfiguration settings, customizablelimits, and up to 60 active or historicdiagnostics are displayed throughthe service tool interface. Withoutchanging any hardware, we give youaccess to the latest and greatestversion of Tracer CH530! A new levelof serviceability using the innovativeTechView chiller service tool, atechnician can interact with anindividual device or a group ofdevices for advancedtroubleshooting. LED lights and theirrespective TechView indicatorsvisually confirm the viability of eachdevice. Any PC that meets the systemrequirements may download theservice interface software and TracerCH530 updates. For more informationon TechView visit your local TraneService company, or The TraneCompany’s website atwww.trane.com.13

GeneralInformationFigure 8. CVHE, CVHF, and CVHG sequence of operation: power up to startingFigure 9. CVHE, CVHF, and CVHG sequence of operation: running14CVHE-SVU01E-EN

GeneralInformationFigure 10. CVHE, CVHF, and CVHG sequence of operation: satisfied setpointFigure 11. CVHE, CVHF and CVHG sequence of operation: normal shutdown to stopped and run inhibitCVHE-SVU01E-EN15

GeneralInformationOil and Refrigeration PumpCompressor Lubrication System A schematic diagram of thecompressor lubrication system isillustrated in Figure 12.Oil is pumped from the oil tank (by apump and motor located within thetank) through an oil pressureregulating valve designed to maintaina net oil pressure of 18 to 22 psid. Itis then filtered and sent to the oilcooler located in the economizer andon to the bearings. From thebearings, the oil drains back to themanifold under the motor and thenon to the oil tank.CAUTIONSurface Temperatures!MAY EXCEED 150 F. Use cautionwhile working on certain areas ofthe unit, failure to do so may resultin minor or moderate injury.16To ensure proper lubrication andprevent refrigerant from condensingin the oil tank, a 750-watt heater isimmersed in the oil tank and is usedto warm the oil while the unit is off.When the unit starts, the oil heater isde-energized. This heater energizesas needed to maintain 140 to 145 F(60-63 C) when the chiller is notrunning.When the chiller is operating, thetemperature of the oil tank is typically115 to 160 F (46-72 C). The oil returnlines from the thrust and journalbearings, transport oil and some sealleakage refrigerant. The oil returnlines are routed into a manifoldunder the motor. Gas flow exits thetop of the manifold and is vented tothe Evaporator. A vent line solenoidis not needed with the refrigerantpump. Oil exits the bottom of themanifold and returns to the tank.Separation of the seal leakage gas inthe manifold keeps this gas out of thetank.A dual eductor system is used toreclaim oil from the suction coverand the evaporator, and deposit itback into the oil tank. These eductorsuse high pressure condenser gas todraw the oil from the suction coverand evaporator to the eductors andthen discharged into the oil tank. Theevaporator eductor line has a shut offvalve mounted by the evaporator andships closed. Open two turns ifnecessary.Liquid refrigerant is used to cool theoil supply to both the thrust bearingand journal bearings. On refrigerantpump units the oil cooler is locatedinside the economizer and usesrefrigerant passing from thecondenser to evaporator to cool theoil. Oil leaves the oil cooler andflows to both the thrust and journalbearings.Motor Cooling SystemCompressor motors are cooled withliquid refrigerant, see Figure 12.The refrigerant pump is located onthe front of the oil tank (motor insidethe oil tank). The refrigerant pumpinlet is connected to the well at thebottom of the condenser. Theconnection is on the side where aweir assures a preferential supply ofliquid. Refrigerant is delivered to themotor via the pump. Motorrefrigerant drain lines are routed tothe condenser.CVHE-SVU01E-EN

GeneralInformationFigure 12. Oil refrigerant pumpCVHE-SVU01E-EN17

GeneralInformationBase Loading ControlAlgorithm:This feature allows an externalcontroller to directly modulate thecapacity of the chiller. It is typicallyused in applications where virtuallyinfinite sources of evaporator loadand condenser capacity are availableand it is desirable to control theloading of the chiller. Two examplesare industrial process applicationsand cogeneration plants. Industrialprocess applications might use thisfeature to impose a specific load onthe facility’s elecrical system.Cogeneration plants might use thisfeature to balance the system’sheating, cooling and electricalgeneration.All chiller safeties and adaptivecontrol functions are in full effectwhen Base Loading control isenabled. If the chiller approaches fullcurrent, the evaporator temperaturedrops too low, or the condenserpressure rises too high, Tracer CH530Adaptive Control logic limits theloading of the chiller to prevent thechiller from shutting down on asafety limit. These limits may preventthe chiller from reaching the loadrequested by the Base Loadingsignal.Base Loading Control is basically avariation of the current limitalgorithm. During base loading, theleaving water control algorithmprovides a load command every 5seconds. The current limit routinemay limit the loading when thecurrent is below setpoint. When thecurrent is within the deadband of thesetpoint the current limit algorithmholds against this loading command.18If the current exceeds the setpoint,the current limit algorithm unloads.The “Capacity Limited By HighCurrent” message normallydisplayed while the current limitroutine is active is suppressed whilebase loading.Base loading can occur via Tracer,External signal, or front panel.Tracer Base Loading:Current Setpoint Range:(20 - 100) percent RLARequires Tracer and Optional TracerCommunications Module (LLID)The Tracer commands the chiller toenter the base load mode by sendingthe base load mode request. If thechiller is not running, it will startregardless of the differential to start(either chilled water or hot water). Ifthe chiller is already running, it willcontinue to run regardless of thedifferential to stop (either chilledwater or hot water), using the baseload control algorithm. While the unitis running in base loading, it willreport that status back to the Tracerby setting “Base Load Status true”in the Tracer Status Byte. When theTracer removes the base load moderequest (sets the bit to 0). The unitwill continue to run, using thenormal chilled or hot water controlalgorithm, and will turn off, onlywhen the differential to stop has beensatisfied.External Base Loading:Current Setpoint Range:(20 - 100) percent RLAThe UCP accepts 2 inputs to workwith external base loading. Thebinary input is at 1A18 Terminals J2-1and J2-2 (Ground) which acts as aswitch closure input to enter thebase-loading mode. The secondinput, an analog input, is at 1A17terminals J2 – 1 and 3 (Ground)which sets the external base loadingsetpoint, and can be controlled byeither a 2-10Vdc or 4-20ma Signal. Atstartup the input type is configured.The graphs in Figure 13 show therelationship between input andpercent RLA. While in base loadingthe active current limit setpoint is setto the Tracer or external base loadsetpoint, providing that the base loadsetpoint is not equal to 0 (or out ofrange). If it is out of range, the frontpanel current limit setpoint is used.During base loading, all limits areenforced with the exception ofcurrent limit. The human interfacedisplays the message “Unit isRunning Base Loaded”. Hot GasBypass is not run during baseloading. If base loading and icemaking are commandedsimultaneously, ice making takesprecedence.An alternative and less radicalapproach to Base Loading indirectlycontrols chiller capacity. Artificallyload the chiller by setting the chilledwater setpoint lower than it iscapable of achieving. Then, modifythe chiller’s load by adjusting thecurrent limit setpoint. This methodprovides greater safety and controlstability in the operation of the chillerbecause it has the advantage ofleaving the chilled water temperaturecontrol logic in effect. The chilledwater temperature control logicresponds quicker to dramatic systemchanges, and can limit the chillerloading prior to reaching an AdaptiveControl limit point.CVHE-SVU01E-EN

GeneralInformationFigure 13. Base loading with external mA input and with external voltage inputCVHE-SVU01E-EN19

GeneralInformationIce Machine ControlThe control panel provides a servicelevel “Enable or Disable” menu entryfor the Ice Building feature when theIce Building option is installed. IceBuilding can be entered 1) from the“Front Panel”, 2) if hardware isspecified, will accept either anisolated contact closure (1A19Terminals J2-1 and J2-2 (Ground) ) 3),a remote communicated input(Tracer) to initiate the ice buildingmode where the unit runs fullyloaded at all times. Ice building willbe terminated either by opening thecontact or based on enteringevaporator fluid temperature. UCPwill not permit the Ice Building modeto be entered again until the unit isswitched to the Non-ice buildingmode and back into the ice buildingmode. It is not acceptable to reset thechilled water setpoint low to achievea fully loaded compressor. Whenentering ice-building the compressorwill be loaded at its maximum rateand when leaving ice building thecompressor will be unloaded at itsmaximum rate. While loading andunloading the compressor, all surgedetection will be ignored. While inthe ice building mode, current limitsetpoints less than the maximum willbe ignored. Ice Building can beterminated by one of the followingmeans:1. Front Panel Disable, or2. Opening the external Ice. Contacts/Remote communicated input(Tracer), or3. Satisfying an evaporator enteringfluid temperature setpoint (Defaultto 27 F).4. Surging for 7 minutes at full openIGV.20Figure 14. CVHE, CVHF and CVHG sequence of operation: ice making: runningto ice makingFigure 15. CVHE, CVHF and CVHG sequence of operation: ice making:stopped to ice to ice building completeCVHE-SVU01E-EN

GeneralInformationFree Cooling CycleBased on the principle that refrigerantmigrates to the coldest area in thesystem, the free cooling optionadapts the basic chiller to function asa simple heat exchanger. However, itdoes not provide control of theleaving chilled water temperature.If condenser water is available at atemperature lower than the requiredleaving chilled water temperature, theoperator interface must remain in“AUTO” and the operator starts thefree cooling cycle by enabling theFree cooling mode in the“DynaView Feature Settings” groupof the operator interface, or by meansof a Tracer request.Several components must be factoryinstalled or field-installed to equip theunit for free cooling operation:— a refrigerant gas line, andelectrically-actuated shutoff valve,between the evaporator andcondenser;— a valve liquid return line, andelectrically-actuated shutoff valve,between the condenser sump andthe evaporator;— a liquid refrigerant storage vessel(larger economizer); and,— additional refrigerant.CVHE-SVU01E-ENWhen the chiller is changed over tothe free cooling mode, thecompressor will shut down ifrunning, the shutoff valves in theliquid and gas lines open; unitcontrol logic prevents thecompressor from energizing duringfree cooling. Liquid refrigerant thendrains (by gravity) from the storagetank into the evaporator and floodsthe tube bundle. Since thetemperature and pressure of therefrigerant in the evaporator arehigher than in the condenser (i.e.,because of the difference in watertemperature), the refrigerant in theevaporator vaporizes and travels tothe condenser. Cooling tower watercauses the refrigerant to condense,and it flows (again, by gravity) backto the evaporator.This compulsory refrigerant cycle issustained as long as a temperaturedifferential exists between condenserand evaporator water. The actualcooling capacity provided by the freecooling cycle is determined by thedifference between thesetemperatures which, in turn,determines the rate of refrigerant flowbetween the evaporator andcondenser shells.If the system load exceeds theavailable free cooling capacity, theoperator must manually initiatechangeover to the mechanicalcooling mode by disabling the freecooling mode of operation. The gasand liquid line valves then close andcompressor operation begins. (SeeFigure 8 beginning at “Auto” mode.)Refrigerant gas is drawn out of theevaporator by the compressor, where21

GeneralInformationit is then compressed anddischarged to the condenser. Most ofthe condensed refrigerant initiallyfollows the path of least resistance byflowing into the storage tank. Thistank is vented to the economizersump through a small bleed line;when the storage tank is full, liquidrefrigerant must flow through thebleed line restriction. Because thepressure drop through the bleed lineis greater than that of the orifice flowcontrol device, the liquid refrigerantflows normally from the condenserthrough the orifice system and intothe economizer.22Free Cooling FRCLTo enable Free Cooling Mode:1. Free Cooling must first be installedand commissioned.2. Enable the Free Cooling mode inthe DynaView Settings Menu3. Press “AUTO”, and if used, closethe external binary input switch(connected to 1A20 J2- 1 to 2) whilethe chiller is in “AUTO”.Free Cooling cannot be entered if thechiller is in “STOP”.If the chiller is in “AUTO” and notrunning, the condenser water pumpwill start. After condenser water flowis proven, Relay Module 1A11 willenergize operating the Free CoolingValves 4B12 and 4B13. The FreeCooling Valves End Switches mustopen within 3 minutes, or an MMRdiagnostic will be generated. Oncethe Free Cooling Valves EndSwitches open, the unit is in the FreeCooling mode. If the chiller is in“AUTO” and running poweredcooling, the chiller will do a friendlyshut down first, (Run: Unload, PostLube, and drive vanes closed). Afterthe vanes have been overdriven,closed and condenser water proven,the Free Cooling relays will beenergized. To disable Free Coolingand return to Powered Cooling, eitherdisable the Free Cooling Mode in theDynaView settings menu if used toenable Free Cooling or “OPEN” theexternal binary input switch to the1A20 Module if it was used to enableFree Cooling. Once Free Cooling isdisabled, the Free Cooling relaysRelay Module 1A11 will de-energizeallowing the Free Cooling valves toclose. The Free Cooling valves endswitches must close within 3minutes or an MMR diagnostic isgenerated. Once the end switchesclose the chiller will return to“AUTO” and powered cooling willresume if there is a call for coolingbased on the differential to start.Note: The manual control of the inletguide vanes is disabled while in theFree Cooling Mode and thecompressor is prevented fromstarting by the control logic.Note: The relay at 1A11-J-2-4 to 6 is aFC auxiliary relay and can be used asrequired.CVHE-SVU01E-EN

GeneralInformationHot Gas BypassThe hot gas bypass (HGBP) controloption is designed to minimizemachine cycling by allowing thechiller to operate stably underminimum load conditions. In thesesituations, the inlet guide vanes are“locked” at a preset minimumposition, and unit capacity isgoverned by the HGBP valve actuator.Control circuitry is designed to allowboth the inlet guide vanes and theHGBP valve to close for unitshutdown.CVHE-SVU01E-ENAfter a chiller starts and is runningthe inlet guide vanes will passthrough the HGBP Cut-In-Vaneposition as the chiller starts to load.As the chiller catches the load andstarts to unload, the inlet guide vaneswill close to the HGBP Cut-In Vaneposition. At this point the movementof t

CVHE-SVU01E-EN 5 An example of a typical model number is: CVHF091NAL00ACU2758W7E8TB C0000000K01G14C10W1A03B1 Model Number Digit Identification C (1st digit) CenTraVac Hermetic V (2nd digit) CenTraVac Hermetic H (3rd digit) Direct Drive F (4th digit) Development sequence 091 (5th, 6th, and 7th digit) Nominal compressor tonnage