Hitachi RAS-10HRNM, Service Manual, Page: 152 / 482

Outdoor unit electrical expansion valve control
1 After supplying power source, the electronic expansion valve is completely opened.
2 When the compressor is stopped, the electronic expansion valve is completely closed to adjust its opening.
3 At starting operation (compressor is operated), opening of the electronic expansion valve is set at a specified opening.
a Specified opening during heating operation: 1 minute
4 During the cooling and the defrosting operations, the electronic expansion valve is set at the specified opening.
5 Normal opening of the electronic expansion valve.
• Coling operation
– 480 pulse (100%)
• Heating operation
1
Set of target temperature
TdSH = 20-25 ºC
2 Simulation PI control for the electronic expansion valve. The electronic expansion valve opening is controlled so
that the thermistor temperatures for the compressor can reach the target temperature.
The electronic expansion valve opening is controlled as shown in the below table when the unit is operated under
the test run (heating operation: indoor temperature 20 ºC / outdoor temperature 7 ºC).
H(V)RNM(1)(E) 3.0HP 4.0HP 5.0HP 6.0HP 8.0HP 10HP 12HP
Expansion valve
opening pulse (%)
130
(27)
110
(22)
130
(27)
150
(34)
160
(33)
200
(41)
240
(50)
N O T E
– The above target is for one of the indoor units at the twin connection with 7.5m piping length.
5 Control System
144
SMGB0060 rev. 1- 12/2010