Protective Control Function - Mitsubishi Heavy Industries SRK20ZD-S1 Technical Manual

(18) Protective control function

(a) Indoor fan motor protection
When the air conditioner is operating and the indoor fan motor is turned ON, if the indoor fan motor has operated at 300 rpm or
under for more than 30 seconds, the unit enters first in the stop mode and then stops the entire system.
TIMER light illuminates simultaneously and the RUN light flashing 6 times at each 8-second.
(b) Dew condensation prevention control [Cooling (including automatic), cooling oriented dehumidifying operation]
(i) Operating conditions: When all of the following conditions are met.
1
When the inverter command speed is higher than 20 rps, and the humidity sensor value is higher than 68% continuously
for more than 20 minutes.
Indoor heat exchanger temperature = < Room temperature –12ºC.
2
(ii) Detail of operation:
Indoor heat exchanger temperature = < Room temperature –12ºC
1
The inverter command speed is reduced 4rps at each 20 seconds. Lower limit speed is 20 rps.
Room temperature –12ºC <Indoor heat exchanger temperature = < Room temperature –8ºC
2
The inverter command speed is maintained for 20 seconds.
3
When this control continues for more than 30 minutes, carry out air flow control.
a) Up/down air flow
When selecting other than Up/down swing or multi-directional air flow, compel flat orientation.
b) Left/right air flow
When selecting other than Left/right swing or multi-directional air flow, compel centralized orientation.
(iii) Reset conditions: When either of the following conditions is satisfied.
1
The humidity sensor value is less than 63%.
2
The inverter command speed is less than 20 rps.
3
Indoor heat exchanger temperature > Room temperature –8ºC.
The inverter command speed is raised by 1rps and kept at that speed for 20 seconds. This process is repeated until the
calculated speed is reached.
(c) Frost prevention for indoor heat exchanger (During cooling or dehumidifying)
◆
< I >
(i) Operating conditions: After the inverter command speed is at a value other than 0 rps for ten minutes, when the indoor
(ii) Detail of operation
1)
Inverter command speed
Indoor fan motor
Outdoor fan motor
4-way valve
2) If the indoor heat exchanger temperature reaches more than 8°C, the inverter command speed shall be limited to 50rps
to restart operation.
(iii) Reset conditions: Indoor heat exchanger temperature reaches more than 8°C, inverter command speed is at a value other
heat exchanger temperature is less than 2.5°C.
0rps
Depends on inverter command speed
OFF
OFF
than 0rps for 10 minutes.
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