Refrigeration Cycle System Protective Control - Mitsubishi SCM40ZS-S Technical Manual

(7) Refrigeration cycle system protective control

(a) Starting condition
This control starts when the following conditions are satisfied.
(i) When it has elapsed 30 minutes after the compressor was changed from OFF to ON in the cooling operation mode
for more than 5 minutes.
(ii) When the compressor speed has satisfied the following conditions.
(iii) When the indoor air temperature of running indoor unit (Th1) and the indoor heat exchanger temperature (Th2) have
satisfied the following condition even on one unit.
Compressor
Unit
speed
60 rps
1
70 rps
2
80 rps
3
(b) Contents of control
(i) Stop the compressor and delay the start, and then restarts.
(ii) Compressor stops by the abnormal stop when the compressor stop has occurred 3 times in one hour.
(8) Crankcase heater
(a) Operating conditions
This control starts when all the conditions below are satisfied.
(i) After the operation mode is changed to stop and the compressor speed becomes 0 rps continuously for 30 minutes.
(ii) When the temperature detected by the outdoor air temperature (Tho-A) is -2°C or lower after the compressor stops.
(b) Detail of operation
The crankcase heater operates, warming up the compressor, then refrigerant begins circulating smoothly when the air-
conditioner starts its heating operation, and heating begins.
(c) Reset conditions
When the temperature detected by the outdoor air temperature (Tho-A) reaches 0°C or higher, or the operation mode
changes from stop to cooling or heating.
(9) Inching prevention
When the compressor becomes to the thermostat operation within 5 minutes since operation start or becomes dehumidifying op-
eration, the operation is continued with the compressor speed of minimum rps forcibly.
(10) Compressor overheat protection
(a) Purpose
(b) Detail of operation
(i)
(Example) Fuzzy
Model
Lower limit speed
(ii)
(11) Current safe
(a) Purpose
Indoor air temperature Indoor air temperature (Th1) and indoor
(Th1, °C)
10 < = Th1 < = 40
3 minutes
3 minutes
3 minutes
95
Item
Cooling
Discharge pipe temperature (˚C)
SCM40, 45, 50 32 rps
SCM60, 71, 80
25 rps
95 105
SCM100, 125 20 rps
95 105
115
-
heat exchanger temperature (Th2)
Th1 - 4 < Th2
Th1 - 3 < Th2
Tho-D
speed 32 rps
105
Heating
105 115
32 rps
32 rps
22 rps
3 minutes
194
-
'16 • SCM-T-199
Duration
5 minute
115
3 minutes