Hitachi RAS-3HVRNS - Device Control System; Device Control System for IVX Series

5.1 Device control system
5.1.1 Device control system for IVX Series
Control subject
Purpose
Cooling operation Heating operation Defrost operation
Control frequency of inverter
compressor
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.
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.
Fixed frequency (stop compressor
during 30 sec. After defrosting
condition was completed)
Opening degree expansion valve of
outdoor unit
Fully open
• 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).
Fully open
Opening degree expansion valve of
indoor unit
• 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.
• 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.
Specified opening degrees
controlled by temp. on the top of
compressor. (Td).
Outdoor fan
• 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
• 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.)
Fan stop.
4-Way valve (RVR) OFF ON OFF
Solenoid valve (SVA) (Equalised
pressure valve)
• 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
• Turn ON for 1 min. at low
pressure switch activation
• Turn ON at pressure control
switch activation.
Turn ON a defrosting
Solenoid valve (SVB) (Liquid return)
Turn ON at starting
RAS-(3-12)H(V)RNM(1)(E)
Turn ON at starting Turn ON at starting
Solenoid Valve (SVF) (Oil return)
Turn ON at compressor operation
RAS-(3-12)H(V)RNM(1)(E)
Turn ON at compressor operation Turn ON at staring
High/Low pressure balance
Turn ON SVA or SVB before
compressor starting
RAS-(8-12)HRNM
— —
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
5 Control System
118
SMGB0060 rev. 1- 12/2010