Midea ATOM B Series - 5 Protection Control

AtomBSeriesVRF50/60Hz  
18  
MideaAtomBSeriesServiceManual
4 NormalOperationControl
4.1 ComponentControlduringNormalOperation
Table3‐4.1:Componentcontrolduringnormalcoolingoperation
Component
Wiringdiagram
label
28‐60model Controlfunctionsandstates
Invertercompressor  COMP ● Controlledaccordingtoloadrequirement
DCfanmotor  FAN
●
Fanspeedcontrolledaccordingtoheatexchangertemperature
(T3),outdoorambienttemperature(T4),dischargetemperature
(T5)andcompressorfrequency.
Electronicexpansionvalve  EEV
●
Controlledaccordingtodischargetemperature
Four-wayvalve ST1
●
Off
Table3‐4.2:Componentcontrolduringheatingoperation
Component
Wiringdiagram
label
28‐60model Controlfunctionsandstates
Invertercompressor  COMP ● Controlledaccordingtoloadrequirement
DCfanmotor  FAN
●
Fanspeedcontrolledaccordingtooutdoorunitheatexchanger
refrigeranttemperature(T3),outdoorambienttemperature(T4)
andcompressorfrequency.
Electronicexpansionvalve  EEV
●
Controlledaccordingtodischargetemperature
Four-wayvalve ST1
●
On

4.2 CompressorOutputControl
Thecompressorrotationspeediscontrolledaccordingtotheloadrequirement.Beforecompressorstartup,theoutdoor
unitfirstestimatestheindoorunitloadrequirementaccordingtothenominalcapacityofindoorunitscurrentlyrunning,
andthencorrectforambienttemperature.Thecompressorsthenstartupaccordingtothecorrectedloadrequirement. 
Duringoperationthecompressorsarecontrolledaccordingtothenominalcapacityofindoorunitscurrentlyrunningand
theindoorunitheatexchangertemperatures.
4.3 CompressorStepControl
Therunningspeedofthecompressorsinrotationspersecond(rps)isonethirdofthefrequency(inHz)oftheelectrical
inputtothecompressormotors.Thecompressorspeedcanbealteredinincrementsof1rps.
4.4 ElectronicExpansionValveControl
ThepositionofelectronicexpansionvalvesEXViscontrolledinstepsfrom0(fullyclosed)to480(fullyopen). 
Incoolingmode:
 Whentheoutdoorunitisinstandby:
 EXVisatposition304(steps)(model28/42)or480(steps)(model36/48/56/60).
 Whentheoutdoorunitisrunning:
 EXViscontrolledaccordingtodischargetemperature(After3minutesinstandbymode).
Inheatingmode:
 Whentheoutdoorunitisinstandby:
 EXVisatposition304(steps)(model28/42)or480(steps)(model36/48/56/60).
 Whentheoutdoorunitisrunning:
 EXViscontrolledaccordingtodischargetemperature(After3minutesinstandbymode).
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