Toshiba MMY-SAP0806HT8P-E Service Manual page 44

Item Description of operation, numerical data, and other information
9. Release 1. SV2 gas balance control
valve control This control function is aimed at achieving gas balance by opening SV2 while
compressors are turned off so as to reduce their startup load the next time they are
turned on.
1) Control conditions
• In cooling, compressors have been turned off.
• In heating, the outdoor unit has been shut down.
2) Control details
• The control point is changed according to P (PD pressure - PS pressure) registered
just before the compressors were turned off.
• When P
• When P < P1, SV2 is closed.
Control points
for PD
pressure
P1, P2
Outdoor unit
2. SV2 high pressure release control
This control function is aimed at mitigating pressure.
1) Control conditions
• Heating operation and cooling operation is in progress (except periods of defrosting
control).
2) Control details
<Heating>
• When PD pressure becomes
• When PD pressure becomes <2.8 MPa, SV2 is closed.
<Cooling>
• When PD pressure becomes 3.75 MPa, SV2 is opened.
• When PD pressure becomes <2.8 MPa, SV2 is closed.
3) Termination conditions
<Heating>
• Shutdown, thermostat OFF, defrosting operation, or cooling operation.
<Cooling>
• Shutdown, thermostat OFF.
3. SV2 low pressure release control
This control function is aimed at preventing a rapid fall in pressure during transient
operation.
The control is always provided except during periods of stoppage or thermostat OFF.
1) Control details
• When PS pressure becomes
• When PS pressure becomes > 0.20 MPa, SV2 is closed.
P1, SV2 is opened. When this results in P < P2, SV2 is closed.
H e t a n i g
Compressors Compressors
O F F
P1 P2 P1
1.3 1.1 1.3
3.4 MPa, SV2 is opened.
0.16 MPa, SV2 is opened.
(Unit: MPa)
C o o n i l g
Compressors
O F F O N
P2 P1 P2
1.1 — —
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Remarks