Hitachi RAS-4HVNC1 - Automatic Control & Maintenance; Automatic Control Functions

A10762290A
15
11. Automatic Control
Thesystemisequippedwiththefollowing
functions.
NOTE
● Three Minute Guard (EnforcedStoppage)
Thisfunctionisutilizedtoprotectthe
compressor.Whenthefunctionisvalid,the
compressordoesnotoperatetheunitforatleast
3minutesafteritstopsoperating,withtheRUN
indicatorturnedON.Theoperationrestarts
automaticallyafter3minutes.
● Three Minute Guard (EnforcedOperation)
Thisfunctionisutilizedtoprotectthe
compressor.Whenthefunctionisvalid,the
compressordoesnotstopoperatingforatleast
3minutesafteritstartsoperating.
However,ifallindoorunitsinthesystemare
stoppedbythewiredcontroller,thecompressor
willstopoperating.
● Oil Return Operation
Thisfunctionisutilizedtopreventoil
accumulationintheheatexchangerofout-of-
serviceindoorunitatcoolingoperation.
 Iftheindoorunitisstoppedcontinuouslyfor
morethan2hours,thisfunctionisoperatedfora
fewminutes.
● Frost Prevention During Cooling Operation
Thisfunctionisutilizedtopreventfrostformation
ontheindoorunitheatexchanger.Whenthe
indoorunitisoperatedatlowdischargeair
temperature,thecoolingoperationswitchesto
fanoperationautomatically.
● Self-Cleaning of Expansion Valve
 Thisfunctionisutilizedtocleantheexpansion
valveautomaticallywhentheoperationstops
duringcoolingoperation.Thesoundofthe
refrigerantowingmaybeheardfromtheindoor
unitduringselfcleaningoperation.However,itis
notabnormal.
● Hot Start During Heating Operation
Thisfunctionisutilizedtopreventcold
dischargedairatstart-upofheatingoperation,
afterdefrostingoperation,etc.Thefanspeed
automaticallyswitchesfromSlowtoLowand
thentothesetfanspeed.Thefanoperation
mightbestoppedforupto2minutes.Atthis
timethelouverisxedhorizontally.
Exceptinthecaseofalongperiodofshutdown,
keepthemainpowerswitchON.Thedrain
dischargemechanismisoperatedifthedrain
levelishigherthanthesetting.
10.1.7 SetbackOperation
Setbackoperationismainlytosustainacomfort
roomairtemperaturewhileoccupantsareoutof
theroom.
Ifthesetbackoperationisenabled,thesetpointis
adjustedforsetback.
Duringthistime,“Setback“isdisplayedonthe
LCD.
Refertothe“Installation&MaintenanceManual”
forthewiredcontrollerandthe“ServiceManual”
fordetails.
A/C
MODE SPEED TEMP
AUTO
LOUV. Adj.
Meeting Room
LOUV.
Setback
Avoid
28.0
Asetbackoperationrequiresextrasettings.
Refertothe“Installation&MaintenanceManual”
forthewiredcontrollerandthe“ServiceManual”
fordetails.
10.2 InAbnormalCondition
10.2.2 PowerFailure
• AlltheindicationsareOFF.
• Oncetheunitstopsduetopowerfailure,the
operationwillnotrestartevenafterthepower
recovers.Performthestartingprocedures
again.
• Incaseoftheinstantaneouspowerfailurefor2
secondsorless,thestandardunitrestartsthe
operationautomatically.
10.2.3 ElectromagneticInterference(EMI)
Therecouldbeacasethatalltheindications
areOFFandtheunitisstopped.Thisisdueto
theactivationofthemicrocomputerfortheunit
protectionfromtheElectromagneticInterference
(EMI).Performthestartingproceduresagain.
10.2.1 Abnormality
• TheRUNindicator(Red)isashing.
• Theindoorunitnumber,thealarmcode,theunit
modelcodeandthenumberoftheconnected
indoorunitsaredisplayedontheLCD.
• Incasethatthepluralindoorunitsare
connectedtoonewiredcontroller,selectthe
objectindoorunitontheLCDtodisplaythe
information.