Device Control System; Device Control System For Ivx Series - Hitachi RAS-5HVRNM1E Service Manual

5 Control System

5.1 Device control system

5.1.1 Device control system for IVX Series

Control subject
Control frequency of inverter
compressor
Opening degree expansion valve of
outdoor unit
Opening degree expansion valve of
indoor unit
Outdoor fan
4-Way valve (RVR)
Solenoid valve (SVA) (Equalised
pressure valve)
Solenoid valve (SVB) (Liquid return)
Solenoid Valve (SVF) (Oil return)
High/Low pressure balance
N O T E
• I.U.: Indoor unit
• O.U.: Outdoor unit
• Tc / Te: Condensing temperature / Evaporating temperature
• Td: Discharge temperature
• Tl: Liquid temperature
• Tg: Gas temperature
118
SMGB0060 rev. 1- 12/2010
Cooling operation
The frequency control is determined
with the next parameters:
• Ratio (I.U. capacity/O.U.
capacity).
• Temperature difference
between air inlet temperature
and setting air temperature.
Fully open
• Control range of expansion
valve opening degree is
determined to optimize I.U. gas
pipe temp. (Tg) - I.U. liquid pipe
temp. (Tl) difference.
• The expansion valve opening
degree is controlled according
to the number of connected I.U.
• Fan step is operated for O.U.
liquid pipe temp. (Te)
stabilization control increased
number of I.U.: step-up
decreased number of I.U.: step-
down
OFF
• Turn ON at starting
• Turn ON for 1 min. at low
pressure switch activation.
RAS-(3-12)H(V)RNM(1)(E)
Turn ON at starting
RAS-(3-12)H(V)RNM(1)(E)
Turn ON at compressor operation
RAS-(3-12)H(V)RNM(1)(E)
Turn ON SVA or SVB before
compressor starting
RAS-(8-12)HRNM
Purpose
Heating operation
The frequency control is
determined with the next
parameters:
• Ratio (I.U. capacity/O.U.
capacity)
• Temperature difference
between air inlet temperature
and setting air temperature.
• Control range of expansion
valve opening degree is
determined to optimize
temperature. on the top of
compressor.
• When number of I.U. is
decreased, determined with
I.U. capacity. Ratio of (before/
after decrease or with above
condition).
• Specified opening degree at
normal control starting.
Afterward, controlled to
optimize I.U. liquid pipe temp.
(Tl)
• The expansion valve opening
degree is controlled according
to the number of connected
I.U.
• Fan Step is controlled
according to O.U. liquid pipe
temp. and temp. on the top of
compressor.
• Increased number of I.U.:
step-up decreased number of
I.U.: step-down (limited the
lowest by outdoor temp.)
ON
• Turn ON at starting
• Turn ON for 1 min. at low
pressure switch activation
• Turn ON at pressure control
switch activation.
Turn ON at starting
Turn ON at compressor operation
—
Defrost operation
Fixed frequency (stop compressor
during 30 sec. After defrosting
condition was completed)
Fully open
Specified opening degrees
controlled by temp. on the top of
compressor. (Td).
Fan stop.
OFF
Turn ON a defrosting
Turn ON at starting
Turn ON at staring
—