Electronic Expansion Valve Pi Control; Step Control Of Outdoor Unit Fans - Daikin RXYQ96PYDN Service Manual

SiUS34-801A_b
6.3

Electronic Expansion Valve PI Control

Main electronic expansion valve EVM control
When the outdoor unit heat exchanging is performed via the evaporator (20SA is set to ON), this
function is used to exert PI control on the electronic expansion valve (Y1E or Y3E) so that the
evaporator outlet superheated degree (SH) will become constant.
SH = Tg - Te
Subcooling electronic expansion valve EVT control
In order to make the maximum use of the subcool heat exchanger, this function is used to exert PI
control on the electronic expansion valve (Y2E, Y3E) so that the evaporator-side gas pipe
superheated degree (SH) will become constant.
SH = Tsh - Te
Refrigerant charge electronic expansion valve EVJ control
While in automatic refrigerant charge mode, this function is used to exert PI control on the opening
degree of the electronic expansion valve (Y2E) in response to outdoor temperature and close the
valve after the completion of refrigerant charge.
For normal operation, fully open this electronic expansion valve.
6.4

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.
RXYQ72P
0 0
1 350
2 370
3 400
4 450
5 560
6 680
7 710
8 750
9 821
* 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.
VRVIII R-410A Heat Pump 60Hz
SH : Evaporator outlet superheated degree (°F)
Tg : Suction pipe temperature (°F) detected by
Te : Low pressure equivalent saturated
Fan revolutions (rpm)
RXYQ96P
0
350
370
400
450
560
680
710
750
821
the heat exchanger gas pipe thermistor R2T.
temperature (°F)
SH: Evaporator outlet superheated degree (°F)
Tsh:Suction pipe temperature (°F) detected by
the subcool heat exchanger outlet thermistor
R5T
Te: Low pressure equivalent saturated
temperature (°F)
RXYQ120P
0
350
370
400
450
560
680
710
775
870
Basic Control
RXYQ144PTJU
0
285/255
360/315
395/365
480/440
560/530
760/730
960/930
1155/1125
1200/1170
Fan1/Fan2
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