Service manual

43
11
Outline of Control
Outdoor Unit
Item Operation explanation and applied data, etc. Remarks
7. Release valve
control
(1) SV2 gas balance control
This control is executed to balance the gas by
opening SV2 while the compressor is off, in order to
decrease the activation load in the next compressor-
ON time. This control is individually executed by the
master outdoor unit and each slave outdoor unit.
1) Control conditions
When the compressor is switched from ON to OFF
operation.
2) Contents of control
• The control point is exchanged by

P
(Pd pressure - Ps pressure) immediately before
the compressor stops.
• When

P≥ P1, SV2 is opened. After SV2 has
been opened, SV2 is turned off when

P<P2.
• When

P<P1, SV2 is closed.
<Table 7a>
kgf/cm
2
G
8. Fixed-speed
compressor
high pressure
release control
This control is to stop the fixed-speed compressor of
each outdoor unit according to Pd pressure value. This
control is individually executed by the master outdoor
unit and each slave outdoor unit.
1) Contents of control
• The fixed-speed compressor stops when Pd
pressure is over P1 (Table 7a).
• Sets the fixed-speed compressor reactivation
time for 10 minutes, and the control
finishes.
(2) SV2 low pressure release control
This control is to prevent pressure drop during
transient operation. This control is individually
executed by the master outdoor unit and each slave
outdoor unit. This control is executed as necessary
except during stop time and thermostat-OFF time.
1) Contents of control
• SV2 is opened when Ps pressure>0.8 kgf/cm
2
G
• SV2 is closed when Ps pressure>1.2 kgf/cm
2
G
(3) SV2 compressor case bypass control
This control is to prevent oil dilution. This control is
individually executed by the master outdoor unit and
each slave outdoor unit.
This control is executed during compressor-ON
(except during oil level detection control).
1) Contents of control
SV2 is opened when the following conditions are
satisfied.
• Compressor status changes from OFF to ON.
• Oil recovery control is performed in cooling
mode.
• SV2 is opened when TK3 sensor detects 2°C or
lower, and closed when TK3 sensor detects
5°C or higher temperature during compressor-
ON time.
• No. of outdoor fan waves is 3 waves or less
during cooling compressor-ON.
• No. 2 compressor
stops with Pd≥,
P1 = 26.5 kgf/cm
2
G
• No. 1 compressor
stops with Pd
≥,
P1 = 27.5 kgf/cm
2
G
Cooling
Master outdoor Master outdoor
compressor OFF compressor ON
P1 P2 P1 P2
In case of master 13 11 — —
In case of slave 13 11 5 4
Pd pressure
control point
P1, P2