Midea V4+R Series User Manual

V4+R VRF 50/60Hz
34 201702
Midea V4+R Series Service Manual
7 Special Control
7.1 Outdoor Unit Duty Cycling
In systems with multiple outdoor units, outdoor unit duty cycling is used to prevent compressor burn out due to
unbalanced oil levels between outdoor units.
Timing of outdoor unit duty cycling:
 After oil return operation.
 After defrosting operation.
 On restart following compressor stop after set temperatures achieved.
Figure 3-7.1 shows an example of duty cycling in a system with 4 outdoor units.
Figure 3-7.1: Duty cycling in a system with 4 outdoor units
1
Notes:
1. The address settings on the outdoor unit main PCBs for “master unit”, “slave unit 1”, “slave unit 2” and “slave unit 3” do not change.
7.2 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 140 minutes and then every 8 hours(cooling for 4hours).
Tables 3-7.1 and 3-7.2 show component control during oil return operation in cooling mode.
Table 3-7.1: Outdoor unit component control during oil return operation in cooling mode
Component
Wiring diagram label
8-12HP
14-16HP
Control functions and states
Inverter compressor A
COMP(INV)
●
●
Controlled according to load requirement
Inverter compressor B
COMP(INV1)
●
DC fan motor A
FANA
●
●
Controlled according to discharge pressure
DC fan motor B
FAN2
●
●
Electronic expansion valve A
EXVA
●
●
Fully open
Electronic expansion valve B
EXVB
●
●
Four-way valve
ST1
●
●
Off
Four-way valve
ST2
●
●
Off
Four-way valve
ST3
●
●
On
Solenoid valve (liquid refrigerant injection)
SV2
●
●
Normal control
Solenoid valve (oil balance)
SV4
●
●
Normal control
Solenoid valve (fast defrosting)
SV5
●
●
Off
Startup control
Normal operation
After oil return operation or
after defrosting operation or
on restart following compressor
stop after set temperatures
achieved
Normal operation
Outdoor unit
duty cycling
Priority
1
Priority
2
Priority
3
Priority
4
Master
Slave 1
Slave 2
Slave 3
Outdoor unit
duty cycling
Priority
4
Priority
1
Priority
2
Priority
3
Master
Slave 1
Slave 2
Slave 3

Midea V4+R Series Specifications

General

Brand	Midea
Model	V4+R Series
Category	Air Conditioner
Language	English