Toshiba MMY-MUP0801HT8P-TR Service Manual page 59

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 suppressing
release the thermostat-OFF due to freezing prevention due to excessive capacity even in Min Hz
control during cooling small capacity operation.
Control condition
Perform when all the following conditions are met.
• It is an outdoor unit with startup priority 1.
• When the compressor frequency is less than A Hz during cooling operation
Compressor
(77cc A3)
(120cc K4)
• When TD(X) ≤ 96 ºC
Control content
• When any of the indoor units that are thermostat-ON detects TCJ ≤ 3 °C or TC1 ≤ 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 > 7 °C or TC1 > 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) > 102 °C is detected
• When the compressor frequency is above A [Hz]
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
Except outdoor
unit priority1
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 ≥ 28 °C and are
turned back on when TO sensor temperature becomes ≤ 25 °C.
• When the compressors are turned on, the heaters are kept on for 10 minutes.
A [Hz]
25.0
20.5
Cooling
compressor1 3.77MPa
compressor2 3.72MPa
compressor1 3.72MPa
compressor2 3.72MPa
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Heating
3.53MPa
3.49MPa
3.45MPa
3.41MPa
Remarks