Midea ATOM B Series - Page 22

AtomBSeriesVRF50/60Hz
  21
Part3‐Control
6 SpecialControl
6.1 OilReturnOperation
Inordertopreventcompressorsfromrunningoutofoil,theoilreturnoperationisconductedtorecoveroilthathasflowed
outofthecompressor(s)and intothepipingsystem.Thisoperationisperformedforallunits includingunits thatarein
standby. 
Timingofoilreturnoperation:
 Whentheinitialcumulativeoperatingtimereachesevery8hours.
Tables3-6.1and3-6.2showcomponentcontrolduringoilreturnoperationincoolingmode.
Table3‐6.1:Outdoorunitcomponentcontrolduringoilreturnoperationincoolingmode
Component
Wiringdiagram
label
28‐60model Controlfunctionsandstates
Invertercompressor  COMP ● Fixedfrequency
DCfanmotor  FAN
●
Normalcontrolascoolingoperation
Electronicexpansionvalve  EEV1
●
Position300(steps)
Four-wayvalve ST1
●
Off
Table3‐6.2:Indoorunitcomponentcontrolduringoilreturnoperationincoolingmode
Component Unitstate Controlfunctionsandstates
Fan
Thermoon Remotecontrollersetting
Standby Remotecontrollersetting
Thermooff Off
Electronicexpansionvalve
Thermoon Normalcontrol
Standby 300(steps)
Thermooff 300(steps)
Tables3-6.3and3-6.4showcomponentcontrolduringoilreturnoperationinheatingmode. 
Table3‐6.3:Outdoorunitcomponentcontrolduringoilreturnoperationinheatingmode
Component Wiringdiagramlabel 28‐60model Controlfunctionsandstates
Invertercompressor  COMP ● Fixedfrequency
DCfanmotor  FAN
●
Fan speed controlled according to
heatexchangertemperature(T3)and
outdoorambienttemperature(T4)
Electronicexpansionvalve  EEV1
●
Position300(steps)
Four-wayvalve ST1
●
Off
Table3‐6.4:Indoorunitcomponentcontrolduringoilreturnoperationinheatingmode
Component Unitstate Controlfunctionsandstates
Fan
Thermoon Operateonsettingfanspeed(Preventcoldwindpriority)
Standby Operateonsettingfanspeed(Preventcoldwindpriority)
Thermooff Off
Electronicexpansionvalve
Thermoon Normalcontrol
Standby 480(steps)
Thermooff 480(steps)
Note：Preventcoldwind：It’sonlyvalidinheatingoperation,andthiscontrolisprioritytoothercontrols(includingheatingoilreturnanddefrost),
Whichdeterminetheconversionbetweensettingfanspeedwithlowfanspeedandturnoffthefanaccordingtotheevaporatorcoiltemperature
T2.