Toshiba MM-A0280HT Service Manual page 36

Item Operation explanation and applied data, etc.
(1) SV2 gas balance control
7. Release valve
This control is executed to balance the gas by
control
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
• When
• When
<Table 7a>
Pd pressure
control point
P1, P2
In case of master
In case of slave
(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
(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
• SV2 is opened when TK3 sensor detects 2°C or
• No. of outdoor fan waves is 3 waves or less
8. Fixed-speed This control is to stop the fixed-speed compressor of
compressor each outdoor unit according to Pd pressure value. This
high pressure control is individually executed by the master outdoor
release control unit and each slave outdoor unit.
1) Contents of control
Outline of Control
Outdoor Unit
(Pd pressure - Ps pressure) immediately before
the compressor stops.
L L
P ≥ P1, SV2 is opened. After SV2 has
been opened, SV2 is turned off when
L L
P<P1, SV2 is closed.
Master outdoor
compressor OFF
P1 P2
13 11
13 11
• SV2 is opened when Ps pressure>0.8 kgf/cm
• SV2 is closed when Ps pressure>1.2 kgf/cm
mode.
lower, and closed when TK3 sensor detects
5°C or higher temperature during compressor-
ON time.
during cooling compressor-ON.
• 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.
37
L L
P
L L
P<P2.
kgf/cm 2 G
Cooling
Master outdoor
compressor ON
P1 P2
— —
5 4
2 G
2 G
• No. 2 compressor
• No. 1 compressor
Remarks
stops with Pd ≥,
P1 = 26.5 kgf/cm 2 G
≥
stops with Pd ,
P1 = 27.5 kgf/cm 2 G
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