Toshiba MMY-MUP0721HT9P-UL Service Manual page 56

Item Description of operation, numerical data, and other information
9. Capacity This control is a capacity release control that is performed for the purpose of
release suppressing the thermostat-OFF due to freezing prevention due to excessive capacity
even in Min speed [rps] during cooling small capacity operation.
control
Control condition
Perform when all the following conditions are met.
• It is an outdoor unit with startup priority 1.
• When the compressor speed is less than A [rps] during cooling operation
Compressor
(77cc A3)
(120cc K4)
• When TD(X) ≤ 204.8°F(96°C)
Control content
• When any of the indoor units that are thermostat-ON detects TCJ ≤ 37°F(3°C) or
TC1 37°F(3°C) while any of the compressors is ON, SV4 (x) is turned ON.
• When any of the indoor units that are thermostat-ON detects TCJ > 45°F(7°C) or TC1
> 45°F(7°C) while any compressor is ON, SV4 (x) is turned OFF.
Release condition
• When the system is stopped and the thermostat is off
• When TD (X) > 216°F(102°C) is detected
• When the compressor speed is above A [rps]
10. High This control function is aimed at automatically shutting down a compressor in an outdoor
pressure unit depending on Pd. It is individuality performed by the header unit and each follower unit.
release 1) Control details
compressor • Compressors are shut down when Pd reaches or exceeds P0
shut down • The Pd control point P0 is switched according to the start priority of the outdoor unit
• The compressor restart prevention timer (2 minutes 30 seconds) is set, and the control
terminated.
Pd control point P0
Outdoor unit
priority1
Outdoor unit
priority 2-5
11. Case This control function is aimed at preventing the accumulation of refrigerant in those case,
heater and is performed by all outdoor units.
control 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 changing of the
compressor motor windings. In this case, a changing 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 TO sensor temperature becomes ≥ 82.4°F(28 °C)
and are turned back on when TO sensor temperature becomes ≤ 77.0°F(25 °C).
• When the compressors are turned on, the heaters are kept on for 10 minutes.
A [rps]
25.0
20.5
Cooling
547psi(3.77MPa)
compressor1
540psi(3.72MPa)
compressor2
540psi(3.72MPa)
compressor1
540psi(3.72MPa)
compressor2
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Heating
512psi(3.53MPa)
506psi(3.49MPa)
500psi(3.45MPa)
495psi(3.41MPa)
Remarks