Electronic Expansion Valve Pi Control - Daikin RMXS-L Series Service Manual

Basic Control
Step
∗
Compressors may operate in a pattern other than those listed in the above tables subject to the
operating conditions. Selection of full load operation to/from unload operation is made with the
unload circuit solenoid valve (Y3S). The full load operation is performed with the Y3S set to OFF,
while the unload operation is performed with the Y3S set to ON.
2.3

Electronic Expansion Valve PI Control

Main Electronic The PI control of the main electronic expansion valve (Y1E) is carried out to keep the evaporator
outlet superheated degree (SH) constant during heating operation in order to make maximum use
Expansion Valve
of the outdoor unit heat exchanger (evaporator).
SH = Ts1 – Te
The optimum initial value of the evaporator outlet superheated degree is 3°C (5.4°F), but varies
depending on the discharge pipe superheated degree of the inverter compressor.
Subcooling The PI control of the subcooling electronic expansion valve (Y3E) is carried out to keep the
evaporator outlet superheated degree
Electronic
subcooling heat exchanger.
Expansion Valve
SH = Tsh – Te
54
Full-load Unload
1 36.0 Hz
2 39.0 Hz
3 43.0 Hz
4 47.0 Hz
5 52.0 Hz
6 52.0 Hz 57.0 Hz
7 57.0 Hz 64.0 Hz
8 62.0 Hz 71.0 Hz
9 68.0 Hz 78.0 Hz
10 74.0 Hz
11 80.0 Hz
12 86.0 Hz
13 92.0 Hz
14 98.0 Hz
15 104.0 Hz
Step Full-load
16 110.0 Hz
17 116.0 Hz
18 122.0 Hz
19 128.0 Hz
20 134.0 Hz
21 140.0 Hz
22 146.0 Hz
23 152.0 Hz
24 158.0 Hz
25 164.0 Hz
26 170.0 Hz
27 175.0 Hz
28 180.0 Hz
29 185.0 Hz
30 190.0 Hz
31 195.0 Hz
SH: Evaporator outlet superheated degree
Ts1: Suction pipe temperature detected by thermistor
R3T
Te: Low pressure equivalent saturation temperature
of the gas pipe in order to make maximum use of the
(SH)
SH: Evaporator outlet superheated degree
Tsh: Subcooling heat exchanger gas pipe temperature
detected by thermistor R6T
Te: Low pressure equivalent saturation temperature
SiUS181631EA
Unload
Functions and Control