Toshiba MMY-MAP1006FT8(J)P-E Service Manual page 80

Item Description of operation, numerical data, and other information
9. Release SV41, 42 low pressure release control
4.
valve control This control function is aimed at providing low pressure protection, and is individually
(cont'd) performed by the header unit and each follower unit.
The control takes place during defrost operation, heating startup pattern control
operation, and cooling operation.
1) Control details (heating)
When PS pressure becomes
pressure becomes
2) Control details (cooling)
When PS pressure and PD pressure become
respectively, SV41 and 42 are opened; when PS pressure and PD pressure
become
5. SV6 valve cooling bypass control
This control is provided for controlling liquid refrigerant bypass to control discharge
temperature-up or temperature inside of the compressor. It works during single
cooling, single heating, collective cooling, collective heating, collective heating and
defrost operation.
1) Control contents (Single cooling)
When TD temperature ≥ 95°C and compression ratio ≥ 3.0, turn SV6 to ON, and
when TD temperature ≤ 83°C or compression ratio ≥ 2.0, turn SV6 to OFF.
2) Control contents (Other operation)
When TD temperature ≥ 95°C and compression ratio ≥ 4.2, turn SV6 to ON, and
when TD temperature ≤ 83°C or compression ratio≥ 3.2, turn SV6 to OFF.
10. High
This control function is aimed at automatically shutting down a compressor in an
pressure outdoor unit depending on PD pressure. It is individually performed by the header unit
and each follower unit.
release
1) Control details
compressor
• Compressors are shut down when PD pressure reaches or exceeds P0.
shutdown
• The compressor restart prevention timer (2 minutes 30 seconds) is set, and
control
the control terminated.
11. Case There are two types of case heaters: a compressor case heater and an accumulator
heater case heater. This control function is aimed at preventing the accumulation of refrigerant
control in those cases, and is performed by all outdoor units.
If the power supply has not been turned on for a specified period before a post-
installation test run, compressor failure may occur. Similarly, when starting
compressors after a long period of no power supply, it is recommended that the power
supply be turned on for a while before operation is resumed, just like a post-installation
test run.
This control function is sometimes used alongside an electrical charging of the
compressor motor windings. In this case, a charging sound may be heard, but this is
normal.
1) Control details
• The heaters are turned on while the compressors are turned off.
• The heaters are turned off when T0 sensor temperature becomes
turned back on when T0 sensor temperature becomes
• When the compressors are turned on, the heaters are kept on for 10 minutes.
0.1 MPa, SV41, 42 are opened; when PS
0.15 MPa, SV41, 42 are closed.
0.19 MPa and 2.2 MPa, respectively, SV41 and 42 are closed.
0.14 MPa and 1.8 MPa,
28 °C, and are
25 °C.
− 79 −
Remarks
• When PD ≥ P0 =
3.45 MPa,
compressor No. 2
(the last one of
two compressors
in terms of startup
order in two
compressor
configuration) is
shut down.
• When PD ≥ P0 =
3.5 MPa,
compressor No. 1
(the first
compressor in
terms of startup
order) is shut
down.