Protection Control - Mitsubishi Electric AHU-KIT-SP Manual

12. Protection control

Protective control is implemented to protect the compressor of the outdoor unit.
If the conditions of the protection control are satisfied, the outdoor unit is temporarily placed in the protection stop state.
When the protection control condition is released, the compressor will run automatically again.
●Compressor inching prevention control
(a) 3-minute timer
When the compressor has been stopped by the thermostat, remote control operation switch or anomalous condition, its restart will be inhibited for 3 minutes.
However, the 3-minute timer is invalidated at the power on the electric power source for the unit.
(b) 3-minute forced operation timer
Compressor will not stop for 3 minutes after the compressor ON. However, it stops immediately when the unit is stopped by means of the ON/OFF switch or
when the thermostat is turned OFF by the change of operation mode.
●Cooling frost protection
To prevent frosting during cooling mode operation, the compressor-OFF if the AHU heat exchanger temperature (detected with Thi-R) drops to 1.0℃
or lower at 4 minutes after the compressor-ON.
If the AHU heat exchanger temperature is 1.0℃ or lower after 5 minutes, the AHU interface is controlled compressor-OFF.
If it becomes 10℃ or higher, the control teminates.
● Heating overload protection
If the AHU heat exchanger temperature (detected with Thi-R) at 63℃ or higher is detected for 2 seconds continuously,
the compressor stops. When the compressor is restarted after 3-minute delay, if a temperature at 63℃ or higher is detected for 2 seconds
continuously within 60 minutes after initial detection and if this is detected 5 times consecutively, the compressor stops with the anomalous stop (E8).
Anomalous stop occurs also when the AHU heat exchanger temperature at 63℃ or higher is detected for 6 minutes continuously.
Compressor OFF
Compressor ON
56
AHU heat exchanger temperature (℃)
63
Compressor-ON capable
5 minutes timer
Compressor-OFF
1.0 10
AHU heat exchanger temperature (℃)
MODEL NAME
Air Handling Unit Interface
MODEL TYPE
AHU-KIT-SP
ISSUE CLASSIFICATION
SPECIFICATION
MORIKAWA
DWG NO.
REV.MARK PAGE
PSZ000Z308
21.09.17
32/38