Toshiba A90-0132, Service Manual

Page: 58 / 176

58
11
Outline of control
Outdoor unit
Item Operation explanation and applied data, etc. Remarks
7. Release valve (1) SV2 gas balance control
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
Δ
P
(Pd pressure - Ps pressure) immediately before the compressor stops.
• When Δ P ≥ P1, SV2 is opened. After SV2 has been opened, SV2 is turned off
when Δ P< P2.
• When Δ P< P1, SV2 is closed.
<Table 7a>
kgf/cm 2 G
Pd pressure Cooling
control point Master outdoor Master outdoor
P1, P2 compressor OFF compressor ON
P1 P2 P1 P2
In case of master 13 11 - -
In case of slave 13 11 5 4
(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.
8. Fixed-speed This control is to stop the fixed-speed compressor of each outdoor unit according to Pd
compressor pressure value. This control is individually executed by the master outdoor unit and each • No. 2 compressor
high pressure slave outdoor unit. stops with Pd ≥ ,
release control 1) Contents of control P1 = 26.5 kgf/cm
2
G
• 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
• No. 1 compressor
control finishes. stops with Pd
≥
,
P1 = 27.5 kgf/cm
2
G