Hitachi RPIM - Device Control System

5.1 Device control system
Purpose of control
Use
Cooling operation Heating operation Defrost mode
Compressor control frequency
with Inverter
Frequency control is determined with
the following parameters:
• Difference between the air inlet
temperature and the set air
temperature.
• Calculate the width of the
change using the amount of the
change.
Frequency control is determined with
the following parameters:
• Difference between the air inlet
temperature and the set air
temperature.
• Calculate the width of the change
using the amount of the change.
Fixed frequency (stop the compressor
for 30 s. once defrost is complete).
Degree of opening of the
outdoor unit expansion valve
Fully open
The control range for the degree of
opening of the expansion valve is
determined to optimise the
temperature at the top of the
compressor.
Fully open
Degree of opening of the
indoor unit expansion valve
The control range for the degree of
opening of the expansion valve is
determined to optimise the difference
in temperature of the I.U. gas pipe
(Tg) - the temperature of the I.U.
liquid piping (Tl).
Degree of opening specified at the
start of normal control. Then
controlled to optimise the temperature
of the I.U. liquid pipe (Tl).
Specified degrees of opening
controlled by the temperature at the
top of the compressor. (Td).
Outdoor fan
The fan speed operates to control the
stabilisation of the O.U. liquid pipe
temperature (Te); (Te) stabilisation
control
The fan speed is controlled in line with
the temperature of the O.U. liquid pipe
and the temperature at the top of the
compressor.
Fan stoppage.
4-way valve (RVR) Off On Off
Solenoid valve (SVS)
(Balanced pressure valve)
Enabled on starting
(4-10)H(V)RNSE
Enabled on starting (4-10)H(V)RNSE Enabled by defrost
High/low pressure balance
• Control by the indoor expansion
valve (2-3 HVRN(1)(S)
• SVA activation before the
compressor is started
(4-10)H(V)RNSE
• Control by the outdoor expansion
valve (2-3 HVRN(1)(S)
• SVA activation before the
compressor is started
(4-10)H(V)RNSE
I.U.: indoor unit.
Tc/Te: condensing temperature / evaporating temperature.
Td: Discharge temperature.
Tl: liquid temperature.
Tg: gas temperature.
Cap: capacity.
5 Control system
160
SMGB0063 rev. 1 - 10/2010