203.743.6741 • 203.798.7313 www.preferred-mfg.com Instruments & Controls Catalog 25 Instruments & Controls 147 FEEDWATER CENTER Overview Boiler feedwater control systems are often the most archaic controls in the steam plant. Poor boiler waterside control contributes to scaling, corrosion, and eventually hot spots and tube failures. The Preferred Feedwater Center can control the surge tank, Deaerator (DA) tank, transfer pumps, and feedwater pumps (on-off or VSD) to improve water quality and feedwater system reliability. Better Feedwater Delivery Control • “Smart” Pump Sequencing • Pump Speed demand based Start-Stop • Header Pressure based Start-Stop • Lead-Lag Sequence • Field Adjustable Parameters Easy to Use • “Overview”, “Alarm”, “Historical Trend” and “Setup” displays enable informed initial setup and process assessment. • In a single NEMA 4 wall-mounted enclosure, the Feedwater Center integrates a modem for off-site monitoring, RS485 Modbus communications and 24 VDC power supplies. • Optional 10” Operator Interface Touchscreen (OIT) provides graphical overviews as well as Ethernet TCP/ IP and BacNet IP communication to BAS systems. Easy to Order, Stock and Field Upgrade • Complete system is ordered using a single part number. • “Plug In” option boards can be used to upgrade a system in the field. Feedwater Center Control System With the optional 10” color touch screen, trend screens are provided to make it easy to tune level and temperature loops. Display brings plant overviews, outdoor reset, alarms and event status and setup displays right to the operator’s touch. Standard Keypad/Display
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203.743.6741 • 203.798.7313www.preferred-mfg.com
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FEEDWATER CENTEROverview
Boilerfeedwatercontrolsystemsareoftenthemostarchaiccontrolsinthesteamplant.Poorboilerwatersidecontrolcontributestoscaling,corrosion,andeventuallyhotspotsand tube failures.ThePreferredFeedwater Center can controlthesurgetank,Deaerator(DA)tank,transferpumps,and feedwater pumps (on-off orVSD) to improvewaterqualityandfeedwatersystemreliability.
EasytoUse• “Overview”, “Alarm”, “Historical Trend” and “Setup”
displays enable informed initial setup and processassessment.
• In a single NEMA 4 wall-mounted enclosure, theFeedwater Center integrates amodem for off-sitemonitoring,RS485Modbus communications and 24VDCpowersupplies.
With the optional 10” color touch screen, trend screens are provided to make it easy to tune level and temperature loops.
Display brings plant overviews, outdoor reset, alarms and event status and setup displays
right to the operator’s touch.Standard Keypad/Display
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Smart Pump SequencingIn“headeredmode,”pumpsareautomaticallysequencedon/off to ensure that the number of pumps in servicemeetsthedemand.Ifanypumpfailstostartwhencalled,the Feedwater Center immediately starts another pumptoreplacethefaultedpump.Theoperatormaymanuallyselect the lead pump or allow the lead pump to rotateautomatically. Additionally, the total number of pumpsin servicemay be set automatically ormanually by theoperator or all pumps may be shutdown by a buildingautomationsystem(BAS)‘enable/disable’contactinput.
LCD Graphic DisplayLCDgraphicdisplaybringsplantoverviews,outdoorreset,alarms and event status and setup displays right to theoperator’stouch.
Alarms & Event SummaryUp to 200 alarms, system events and operator actionsarelistedin“firstinfirstout”orderwithatime/datestamp.Alarms includesystemfault,pump failureandbothoverandundertemperatureconditions.
Hard Manual BackupHardwired control switches and dials provide simplemanual control for easy troubleshooting and service.Eachpumphasanindividualspeeddemandbargraph,amanualspeeddemandoutputknob,andanauto/manualswitch.
Modbus Communication InterfaceAfactoryconfiguredRS485MODBUSinterfaceisavailableforbuildingautomationorSCADAsystemmonitoringandcontrol.
Optional FeaturesThe Feedwater Center has many features that can beaddedorremovedaccordingtoyourneeds.Thiscontrollerwasdesignedtoaccommodatetheneedsofany1-4pumpsystem.Itisabletorunwithasurgeandadeaeratortank(oroneofeach,ornone).Itaccommodates0-3transferpumpsand0-4feedwaterpumps.TheJC-FWC-FCcanbeusedinheaderedpumpapplicationsaswellasindividualfeedwaterpumps toeachboiler. TheJC-FWC-FCcanhaveallofthesefollowingsensors;
Aswellascontrolling thespeedsofup to three transferpumpsandfourboilerfeedpumps.TheFeedwaterCentercontrols a number of valves in order tomaintain levels/pressures/flowrateswithinthesystem.
FEEDWATER CENTER MODEL JC-FWC-FCFeedwaterDeliveryController
ApplicationTheFeedwaterCenterModel JC-FWC-FC includesallavailablefeatures and capabilities required to control feedwaterdeliverysystemsincludingDAlevelandpressurecontrol,surgetanklevelcontrol,transferpumpcontrol,feedwaterpump control, chemical feed pump control andwatersoftenerregeneration.
JC-FWC-FC, Full Control
Up to 4 Feedwater PumpsPumpsuse“smart”sequencingtoensurethepropernumberofpumpsarerunningtosatisfythefeedwaterdemand.
deaerator tank
surge tank
Boiler 1 Run (Boiler Limits, One per Boiler)
Surge Tank Make Up Water Valve
Surge Tank Low Level Sensor
DA Tank Level Control Valve
DA Tank Level
To Boilers (Header Piped or Optional Per Boiler Set Up)
DA Tank PSI
Chemical Feed Valve
Feedwater Pumps
Transfer Pumps
Condensate Return Line Temperature
DA Tank Temperature
FW H
eade
r PSI
Proof of FlowBoiler Feedwater Pump ONBoiler Feedwater Pump Speed Control
Proof of FlowTransfer Pump ONTransfer Pump Speed Control
DA Tank PSI Control Valve
DA Tank Low Level Sensor
PT LT TELS
PS
Chem
ical F
eed
Make Up Water Line
Water Softener
Typical Per Pump
Typical Per Pump
Condensate Return Line Flow
Steam Header Pressure
LS
Surge Tank Level
LTPT FT
Make Up Water PSIMake Up Water Flow
Soft Water Regen
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FEEDWATER CENTER MODEL JC-FWC-FCFeedwaterDeliveryController-Specification
1. ApplicationSupplyafullyintegratedFeedwaterControlsystemtocoordinatetheoperationof(upto)fourVSDcontrolledFeedwaterpumps,Daearatorlevelandpressurecontrol,(upto)threetransferpumps,watersoftenerregenerationandchemicalfeed.Thecontrolsystemshallbemicroprocessor-basedandsuitableforwallmounting.2. Pump VSD ModulationThecontrol systemshallprovideaPIDbasedcontrol scheme.Asdemandincreases,thespeedofthepumpwillincrease.Eachrunningpumpwillmodulateinunison.Modulationsignalsshallbe4-20mADCandshallbeelectricallyisolatedchannel-channelandchannel-ground.3. Headered Feedwater Pressure SetpointTheFeedwaterpressuresetpointmustbefieldselectablebetweensteamheaderbasedormanual.Insteamheaderbasedmode,theFeedwaterpressuresetpointmustbecalculatedbasedonanadjustabledeviationfromtheactualsteamheaderpressure.Inmanual, theoperatormaysettheFeedwaterHeaderPressureSetpointviaafrontpaneldisplay.4. Pump SequenceThecontrolsystemshallusebothFeedwaterheaderpressure(Deaerator level for transfer pumps) andpumpspeed to startandstopthepumpsandminimizethetotalnumberofpumpsinoperation.Thecontroller shall startandstoppumpswhen theFeedwaterheaderpressureisoutsideanadjustablepressurelimitbandforlongerthananadjustableshorttimedelay.Toanticipateandminimize header pressure deviations, the control systemshallstartorstopthenextpumpifthe“lead”pumphasbeennearmaximumorminimumspeedforlongerthantheadjustabletimedelay.Thecontrolsystemshallmonitoreachpump’sflowswitchandshallrapidlyandautomaticallyreplaceanypumpthatfailsto prove flow.The leadpumpshall either automatically rotateonatimeofday/dayofweek(ormonth)schedule,orshallbemanuallyselectedbytheoperator.Thecontrolsystemshallbefieldadjustableto“perboiler”modewhichwouldrunonefeedwaterpumpper boiler.Additionally, the control systemshall be fieldadjustabletochoosebetweenheaderedorboilerspecificpipingtodeterminewhichpumpsshouldbestarted.A120VACDiscreteinputistobeprovidedasaDeaeratorlowlevelsignalthatdisablesallFeedwaterPumps.A120VACDiscreteinputistobeprovidedasasurgetanklowlevelsignalthatdisablesalltransferpumps.5. Deaerator ControlThecontrolsystemshalloutputademandsignalbasedonDALevel. When usedwith transfer pumps, this is the speed atwhichthetransferpumpsmustrun.Withouttransferpumps,thiswoulddrivealevelcontrolvalve.ThecontrolsystemshalldriveaDeaeratorpressurecontrolvalvebasedonDeaeratorpressure.6. Surge Tank ControlThe control system shall output a command to a freshwatermakeupvalvebasedonsurgetanklevel.Fieldadjustablelevelforvalveat0%openandvalveat100%openshallbeprovided.
7. Chemical Feed ControlThecontrolsystemshallmonitormakeupwaterflowandsendthatflowsignaltoachemicalfeedpump.8. Soft Water Regeneration ControlThecontrolsystemshallinitiateasoftwaterregenerationcyclebasedontime,oruponreceivingasoftwateralarm.Theoperatorshall alsobeable to initiate the softwater regeneration cyclemanually.9. Monitor PointsThecontrolsystemshallmonitorDeaerator temperature, freshwatermakeuppressure,condensatereturnflowandcondensatereturntemperaturefordisplaypurposes.10. Operator Controls, Trends, Indications and AlarmsThe control system shall include a 16 line x 40 character (orgreater)LCDdisplayforboilersequencecontrolandstatus,alarmandeventsummaries,andsetupmenusforeasyoperation,tuningandtroubleshooting.Alarms,eventsandoperatoractionsshallbeloggedwithtime/datestampandEnglishlanguagedescription.11. CommunicationTheControl System shall have the ability of simultaneouslycommunicating to aDataAcquisitionSystem (DAS),BuildingAutomation System (BAS) or BuildingManagement System(BMS)viaRS485Modbusprotocolandtoapersonalcomputer.Theindividualboilerlimits,lockout,start/stop,warmstandby,andfiringratestatusshallbeeasilyread.Headersetpoint,plantfiringrate,boilerquantitycalledtostart,boilerselectedasleadandallsetupparametersshallbereadableandwritable.12. Quality AssuranceThe control system shall bemanufactured and labeled inaccordancewithUL508requirements(CSAC22.2#14foruseinCanada).InspectionandlabelingshallbesupervisedbyULorotherOSHAapprovedNationallyRecognizedTestLab(NRTL).Thecontrol systemshall beaPreferred Instruments,Danbury,CT,Model JC-FWC-FC.
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FEEDWATER CENTER MODEL JC-FWC-NVFeedwaterDeliveryController
ApplicationTheFeedwaterCenterModel JC-FWC-NV includesallavailablefeatures and capabilities required to control feedwaterdeliverysystemsincludingDAlevelandpressurecontrol,surgetanklevelcontrol,transferpumpcontrol,feedwaterpump control, chemical feed pump control andwatersoftenerregeneration.
JC-FWC-NV, Full Control for pumps without VSDs
Up to Four Feedwater PumpsPumpsuse“smart”sequencingtoensurethepropernumberofpumpsarerunningtosatisfythefeedwaterdemand.
deaerator tank
surge tank
Boiler 1 Run (Boiler Limits, One per Boiler)
Surge Tank Make Up Water Valve
Surge Tank Low Level Sensor
DA Tank Level Control Valve
DA Tank Level
To Boilers (Header Piped or Optional Per Boiler Set Up)
DA Tank PSI
Chemical Feed Valve
Feedwater Pumps
Transfer Pumps
Condensate Return line Temperature
DA Tank Temperature
FW H
eade
r PSI
Proof of FlowBoiler Feedwater Pump ON
Proof of flowTransfer Pump ON
DA Tank PSI Control Valve
DA Tank Low Level Sensor
PT LT TE
LS
PS
Chem
ical F
eed
Make Up Water Line
Water Softener
Typical Per Pump
Typical Per Pump
Condensate Return line Flow
Steam Header Pressure
LS
Surge Tank Level
LTPT FT
Make Up Water PSIMake Up Water Flow
Soft Water Regen
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FEEDWATER CENTER MODEL JC-FWC-NVFeedwaterDeliveryController-Specification
1. ApplicationSupplyafullyintegratedFeedwatercontrolsystemtocoordinatetheoperationof(upto)fourFeedwaterpumps,Daearatorlevelandpressurecontrol,(upto)threetransferpumps,watersoftenerregeneration and chemical feed.The control system shall bemicroprocessor-basedandsuitableforwallmounting.2. Headered Feedwater Pressure SetpointTheFeedwaterpressuresetpointmustbefieldselectablebetweensteamheaderbasedormanual.Insteamheaderbasedmode,theFeedwaterpressuresetpointmustbecalculatedbasedonanadjustabledeviationfromtheactualsteamheaderpressure.Inmanual,theoperatormaysettheFeedwaterheaderpressuresetpointviaafrontpaneldisplay.3. Pump SequenceThe control system shall use Feedwater Header Pressure(Deaerator Level for Transfer Pumps) to start and stop thepumpsandminimize the total number of pumps in operation.Thecontrollershallstartandstoppumpswhen theFeedwaterheaderpressureisoutsideanadjustablepressurelimitbandforlongerthananadjustableshorttimedelay.Thecontrolsystemshallmonitor each pump’s flow switch and shall rapidly andautomaticallyreplaceanypumpthatfailstoproveflow.Theleadpumpshalleitherautomaticallyrotateonatimeofday/dayofweek(ormonth)schedule,orshallbemanuallyselectedbytheoperator.Thecontrolsystemshallbefieldadjustableto“perboiler”modewhichwouldrunonefeedwaterpumpperboiler.Additionally,thecontrolsystemshallbefieldadjustabletochoosebetweenheadered or boiler specific piping to determinewhich pumpsshouldbestarted.A120VACDiscreteinputistobeprovidedasaDeaeratorlowlevelsignalthatdisablesallFeedwaterpumps.A120VACDiscreteinputistobeprovidedasasurgetanklowlevelsignalthatdisablesalltransferpumps.4. Deaerator ControlThecontrolsystemshalloutputademandsignalbasedonDAlevel.Whenusedwithtransferpumps,thisisthespeedatwhichthetransferpumpsmustrun.Withouttransferpumps,thiswoulddrivealevelcontrolvalve.ThecontrolsystemshalldriveaDeaeratorpressurecontrolvalvebasedonDeaeratorpressure.5. Surge Tank ControlThe control system shall output a command to a freshwatermakeupvalvebasedonsurgetanklevel.Fieldadjustablelevelforvalveat0%openandvalveat100%openshallbeprovided.6. Chemical Feed ControlThecontrolsystemshallmonitormakeupwaterflowandsendthatflowsignaltoachemicalfeedpump.7. Soft Water Regeneration ControlThecontrolsystemshallinitiateasoftwaterregenerationcyclebasedontime,oruponreceivingasoftwateralarm.Theoperatorshall alsobeable to initiate the softwater regeneration cyclemanually.
8. Monitor PointsThecontrolsystemshallmonitorDeaerator temperature, freshwatermakeuppressure,condensatereturnflowandcondensatereturntemperaturefordisplaypurposes.9. Operator Controls, Trends, Indications and AlarmsThe control system shall include a 16 line x 40 character (orgreater)LCDdisplayforboilersequencecontrolandstatus,alarmandeventsummaries,andsetupmenusforeasyoperation,tuningandtroubleshooting.Alarms,eventsandoperatoractionsshallbeloggedwithtime/datestampandEnglishlanguagedescription.10. CommunicationThe control system shall have the ability of simultaneouslycommunicating to aDataAcquisitionSystem (DAS),BuildingAutomation System (BAS) or BuildingManagement System(BMS)viaRS485Modbusprotocolandtoapersonalcomputer.Theindividualboilerlimits,lockout,start/stop,warmstandby,andfiringratestatusshallbeeasilyread.Headersetpoint,plantfiringrate,boilerquantitycalledtostart,boilerselectedasleadandallsetupparametersshallbeeasilyreadandwritten.11. Quality AssuranceThe control system shall bemanufactured and labeled inaccordancewithUL508requirements(CSAC22.2#14foruseinCanada).InspectionandlabelingshallbesupervisedbyULorotherOSHAapprovedNationallyRecognizedTestLab(NRTL).Thecontrol systemshall beaPreferred Instruments,Danbury,CT,Model JC-FWC-NV.
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FEEDWATER CENTER MODEL JC-FWC-NSFeedwaterDeliveryController
ApplicationTheFeedwaterCenterModel JC-FWC-NS includesallavailablefeatures and capabilities required to control feedwaterdeliverysystemsincludingDAlevelandpressurecontrol,feedwaterpumpcontrol,chemicalfeedpumpcontrolandwatersoftenerregeneration.
JC-FWC-NS, Full Control for systems without surge tanks
Up to Four Feedwater PumpsPumpsuse“smart”sequencingtoensurethepropernumberofpumpsarerunningtosatisfythefeedwaterdemand.
deaerator tank
Boiler 1 Run (Boiler Limits, One per Boiler)
DA Tank Level Control Valve
DA Tank Level
To Boilers (Header Piped or Optional Per Boiler Set Up)
DA Tank PSI
Chemical Feed Valve
Feedwater Pumps
Condensate Return Line Temperature
DA Tank Temperature
FW H
eade
r PSI
Proof of FlowBoiler Feedwater Pump ONBoiler Feedwater Pump Speed Control
DA Tank PSI Control Valve
DA Tank Low Level Sensor
PT LT TE
LS
PS
Chem
ical F
eed
Make Up Water Line
Water Softener
Typical Per Pump
Condensate Return Line Flow
Steam Header Pressure
PT FT
Make Up Water PSIMake Up Water Flow
Soft Water Regen
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FEEDWATER CENTER MODEL JC-FWC-NSFeedwaterDeliveryController-Specification
1. ApplicationSupplyafullyintegratedFeedwatercontrolsystemtocoordinatetheoperationof(upto)fourVSDcontrolledFeedwaterpumps,Daearatorlevelandpressurecontrol,watersoftenerregenerationandchemicalfeed.Thecontrolsystemshallbemicroprocessor-basedandsuitableforwallmounting.2. Pump VSD ModulationThecontrol systemshallprovideaPIDbasedcontrol scheme.Asdemandincreases,thespeedofthepumpwillincrease.Eachrunningpumpwillmodulateinunison.Modulationsignalsshallbe4-20mADCandshallbeelectricallyisolatedchannel-channelandchannel-ground.3. Headered Feedwater Pressure SetpointTheFeedwaterpressuresetpointmustbefieldselectablebetweensteamheaderbasedormanual.Insteamheaderbasedmode,thefeedwaterpressuresetpointmustbecalculatedbasedonanadjustabledeviationfromtheactualsteamheaderpressure.Inmanual, theoperatormayset theFeedwaterheaderpressuresetpointviaafrontpaneldisplay.4. Pump SequenceThecontrolsystemshallusebothFeedwaterheaderpressureandpumpspeedtostartandstopthepumpsandminimizethetotal number of pumps in operation.The controller shall startandstoppumpswhentheFeedwaterheaderpressureisoutsideanadjustablepressurelimitbandforlongerthananadjustableshort timedelay.Toanticipate andminimizeheader pressuredeviations,thecontrolsystemshallstartorstopthenextpumpifthe“lead”pumphasbeennearmaxorminspeedforlongerthantheadjustabletimedelay.Thecontrolsystemshallmonitoreachpump’sflowswitchandshall rapidlyandautomaticallyreplaceanypump that fails to prove flow.The leadpumpshall eitherautomatically rotateona timeofday/dayofweek (ormonth)schedule,or shall bemanually selectedby theoperator. Thecontrolsystemshallbefieldadjustableto“perboiler”modewhichwouldrunonefeedwaterpumpperboiler.Additionally,thecontrolsystemshallbefieldadjustabletochoosebetweenheaderedorboilerspecificpipingtodeterminewhichpumpsshouldbestarted.A120VACDiscreteinputistobeprovidedasaDeaeratorlowlevelsignalthatdisablesallFeedwaterpumps.5. Deaerator ControlThecontrolsystemshall triggerademandsignalbasedonDALevel.When usedwith transfer pumps, this is the speed atwhichthetransferpumpsmustrun.Withouttransferpumps,thiswoulddrivealevelcontrolvalve.ThecontrolsystemshalldriveaDeaeratorpressurecontrolvalvebasedonDeaeratorpressure.6. Chemical Feed ControlThecontrolsystemshallmonitormakeupwaterflowandsendthatflowsignaltoaChemicalfeedpump.7. Soft Water Regeneration ControlThecontrolsystemshallinitiateasoftwaterregenerationcyclebasedontime,oruponreceivingasoftwateralarm.Theoperatorshallalsobeabletomanuallystartthesoftwaterregenerationcycle.
9. Monitor PointsThecontrolsystemshallmonitorDeaerator temperature, freshwatermakeuppressure freshwatermakeup flow, condensatereturn flow and condensate return temperature for displaypurposes.10. Operator Controls, Trends, Indications and AlarmsThe control system shall include a 16 line x 40 character (orgreater)LCDdisplayforboilersequencecontrolandstatus,alarmandeventsummaries,andsetupmenusforeasyoperation,tuningandtroubleshooting.Alarms,eventsandoperatoractionsshallbeloggedwithtime/datestampandEnglishlanguagedescription.11. ReliabilityIncludehardwiredbackupstations topermitmanual operationoftheplantshouldthecontrolsystemrequireservice.Manualoperationmust be possiblewhen themicroprocessor is notfunctioning.Hardwired “hand-off-auto” control switchesmustbewireddirectlyintoeveryboilerstart/stopcircuit.Each4-20mADCor0-135ohmmodulatingcontroloutputmust includeahardwiredmanualbackupstationwithauto/manualswitch,outputcontrolknobandoutputlevelindicator(bargraph,analogmeterordigitaldisplay).12. CommunicationThe control system shall be capable of simultaneouslycommunicating to aDataAcquisitionSystem (DAS),BuildingAutomation System (BAS) or BuildingManagement System(BMS)viaRS485Modbusprotocolandtoapersonalcomputer.Theindividualboilerlimits,lockout,start/stop,warmstandby,andfiringratestatusshallbeeasilyread.Headersetpoint,plantfiringrate,boilerquantitycalledtostart,boilerselectedasleadandallsetupparametersshallbeeasilyreadandwritten.13. Quality AssuranceThe control system shall bemanufactured and labeled inaccordancewithUL508requirements(CSAC22.2#14foruseinCanada).InspectionandlabelingshallbesupervisedbyULorotherOSHAapprovedNationallyRecognizedTestLab(NRTL).Thecontrol systemshall beaPreferred Instruments,Danbury,CT,Model JC-FWC-NS.
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FEEDWATER CENTER MODEL JC-FWC-NVSFeedwaterDeliveryController
ApplicationThe Feedwater CenterModel JC-FWC-NVS includes allavailable features and capabilities required to controlfeedwaterpumps.
JC-FWC-NVS, Full Control for systems without surge tank or VSD controlled pumps
Up to Four Feedwater PumpsPumpsuse“smart”sequencingtoensurethepropernumberofpumpsarerunningtosatisfythefeedwaterdemand.
deaerator tank
Boiler 1 Run (Boiler Limits, One per Boiler)
DA Tank Level
To Boilers (Header Piped or Optional Per Boiler Set Up)
Feedwater Pumps
FW H
eade
r PSI
Proof of FlowBoiler Feedwater Pump ON
DA Tank Low Level Sensor
LT
LSPS
Typical Per Pump
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FEEDWATER CENTER MODEL JC-FWC-NVSFeedwaterDeliveryController-Specification
1. ApplicationSupplyafullyintegratedFeedwatercontrolsystemtocoordinatetheoperationof(upto)fourFeedwaterpumps.Thecontrolsystemshallbemicroprocessor-basedandsuitableforwallmounting.2. Headered Feedwater Pressure SetpointTheFeedwaterpressuresetpointmustbefieldselectablebetweenSteamheaderbasedormanual.Insteamheaderbasedmode,theFeedwaterpressuresetpointmustbecalculatedbasedonanadjustabledeviationfromtheactualSteamheaderpressure.Inmanual,theoperatormaysettheFeedwaterheaderpressuresetpointviaafrontpaneldisplay.3. Pump SequenceThecontrolsystemshalluseFeedwaterheaderpressuretostartandstopthepumpsandminimizethetotalnumberofpumpsinoperation.Thecontroller shall startandstoppumpswhen theFeedwaterheaderpressureisoutsideanadjustablepressurelimitbandforlongerthananadjustableshorttimedelay.Thecontrolsystemshallmonitoreachpump’sflowswitchandshallrapidlyandautomaticallyreplaceanypumpthatfailstoproveflow.Theleadpumpshalleitherautomaticallyrotateonatimeofday/dayofweek(ormonth)schedule,orshallbemanuallyselectedbytheoperator.Thecontrolsystemshallbefieldadjustableto“perboiler”modewhichwouldrunonefeedwaterpumpperboiler.Additionally,thecontrolsystemshallbefieldadjustabletochoosebetweenheadered or boiler specific piping to determinewhich pumpsshouldbestarted.A120VACDiscreteinputistobeprovidedasaDeaeratorlowlevelsignalthatdisablesallFeedwaterpumps.4. Operator Controls, Trends, Indications and AlarmsThe control system shall include a 16 line x 40 character (orgreater)LCDdisplayforboilersequencecontrolandstatus,alarmandeventsummaries,andsetupmenusforeasyoperation,tuningandtroubleshooting.Alarms,eventsandoperatoractionsshallbeloggedwithtime/datestampandEnglishlanguagedescription.Thecontrolsystemshallincludeaminimumof200pointmemory.5. ReliabilityIncludehardwiredbackupstations topermitmanual operationof theplantshould thecontrolsystemrequireservice.Manualoperationmust be possiblewhen themicroprocessor is notfunctioning.Hardwired “hand-off-auto” control switchesmustbewireddirectlyintoeveryboilerstart/stopcircuit.Each4-20mADCor0-135ohmmodulatingcontroloutputmust includeahardwiredmanualbackupstationwithauto/manualswitch,outputcontrolknobandoutputlevelindicator(bargraph,analogmeterordigitaldisplay).
6. CommunicationThe control system shall have the ability of simultaneouslycommunicating to aDataAcquisitionSystem (DAS),BuildingAutomation System (BAS) or BuildingManagement System(BMS)viaRS485Modbusprotocolandtoapersonalcomputer.Theindividualboilerlimits,lockout,start/stop,warmstandby,andfiringratestatusshallbereadable.Headersetpoint,plantfiringrate,boilerquantitycalledtostart,boilerselectedasleadandallsetupparametersshallbeeasilyreadandwritten.7. Quality AssuranceThe control system shall bemanufactured and labeled inaccordancewithUL508requirements(CSAC22.2#14foruseinCanada).InspectionandlabelingshallbesupervisedbyULorotherOSHAapprovedNationallyRecognizedTestLab(NRTL).Thecontrol systemshall beaPreferred Instruments,Danbury,CT,Model JC-FWC-NS.