Electronic Expansion Valve Pi Control; Step Control Of Outdoor Unit Fans - Daikin VRV III RXYQ5-54PY1 Service Manual

Si34-601A
2.3

Electronic Expansion Valve PI Control

Main Motorized Valve EV1 Control
Carries out the motorized valve (Y1E) PI control to maintain the evaporator outlet superheated
degree (SH) at constant during heating operation to make maximum use of the outdoor unit
heat exchanger (evaporator).
SH = Ts1 - Te
The optimum initial value of the evaporator outlet superheated degree is 5°C, but varies
depending on the discharge pipe superheated degree of inverter compressor.
Subcooling Motorized Valve EV2 Control
Makes PI control of the motorized valve (Y2E) to keep the superheated degree of the outlet gas
pipe on the evaporator side for the full use of the subcooling heat exchanger.
SH = Tsh -Te
2.4

Step Control of Outdoor Unit Fans

Used to control the revolutions of outdoor unit fans in the steps listed in table below, according to condition changes.
STEP
No.
RXYQ5P
0 0
1 285
2 315
3 360
4 450
5 570
6 710
Cooling: 951
7
Heating: 941
Cooling: 951
8
Heating: 941
* Figures listed above are all those controlled while in standard mode, which vary when the system is set to high static
pressure or capacity precedence mode.
Function
RXYQ8P RXYQ10P
0 0
350 350
370 370
400 400
450 460
540 560
670 680
Cooling: 821
760
Heating: 800
Cooling: 796 Cooling: 821
Heating: 780 Heating: 800
SH : Evaporator outlet superheated degree (°C)
Ts1: Suction pipe temperature detected by
thermistor R6T (R7T) (°C)
Te : Low pressure equivalent saturation
temperature (°C)
SH : Outlet superheated degree of evaporator (°C)
Tsh : Suction pipe temperature detected with the
thermistor R5T (°C)
Te : Low pressure equivalent saturation
temperature (°C)
Fan revolutions (rpm)
RXYQ12P
(except Europe)
RXYQ12P
RXYQ14P
(Europe)
FAN1 FAN2 FAN1 FAN2 FAN1 FAN2
0 0
350 230
370 380
400 290
460 375
560 570
680 720
870 1091
870 1136
Basic Control
RXYQ16P RXYQ18P
0 0 0 0
0 230 0 395
0 380 0 460
260 290 260 570
345 375 345 385
540 570 540 550
690 720 690 800
1061 1091 1061 1136
1106 1136 1106 1166
0
0
0
0
355
520
770
1106
1136
107