Other Control; Overload Control; Pump-Down Control; Recover Refrigerant To Outdoor Unit - Midea VRF Series Service Manual

V6R VRF 50/60Hz

8 Other Control

8.1 Overload control

Overload control is used to maintain comfort requirement (i.e. outlet air temperature) and keep proper system pressure.
Figure 3-8.1: Overload control
Indoor unit operation ratio
Notes:
1. Indoor unit operation ratio = Indoor unit operates capacity index (in the same mode)/ outdoor unit capacity index

8.2 Pump-down Control

Recover refrigerant to outdoor unit

Recover refrigerant to outdoor unit is used to recover the refrigerant from indoor units and MS box before service work. The
LED display r001 in this control.
Table 3-8.1: Recover refrigerant to outdoor unit
Component
Inverter
compressor A
Inverter fan 1
Inverter fan 2
Four way valve
ODU
Electronic
expansion valve
Solenoid valve
Electric ball
valve
MS01
Electronic
expansion valve
Solenoid valve
MS04-12
Electronic
expansion valve
Fan
IDU
Electronic
expansion valve
Ending conditions
Notes:
1. Pc: Discharge pressure Pe: Suction pressure
2. Tes : Target evapating temperature
46
Normal operation
130%
≥
Overload control, indoor units operates in
low fan speed
Wiring Startup
control
diagram label
INV1
FANA
FANB
ST1 OFF
EEVA
EEVC
SV5
SV8A
SV7
EVBA
EVBB
EVBC
EEVA
Refer to
startup control
SV(n)A
in cooling
SV(n)B
operation
SVP
EEVA
Fan
EEV
T7C1: Compressor discharge temperature
Indoor unit operation ratio <105%
Normal control
Tes = -15°C
30Hz
Upper limit: 60 Hz
PI control PI control
OFF OFF
2880pls 2880pls
0pls 0pls
ON ON
ON ON
OFF OFF
Cooling only normal control
30min or Pe< 0.2MPa
Pump down
Meet any points below:
• Pump down time elapses 5min.
• Pe < 0.12MPa
• T7C1_Max ≥ 105°C
• Pc ≥ 3.6MPa