Mitsubishi Heavy Industries SRK20ZIX-S Service Manual page 65

(2) Cooling overload protective control
(a) Operating conditions: When the outdoor air temperature (TH2) has become continuously for 30 seconds at 41ºC or
(b) Detail of operation
1) The outdoor fan is stepped up by 3 speed step. (Upper limit 7th (model 50 : 8th) speed.)
2) The lower limit of compressor command speed is set to 30 or 40 (SRF50 : 30) rps and even if the calculated result be-
comes lower than that after fuzzy calculation, the speed is kept to 30 or 40 (SRF50 : 30) rps. However, when the thermo
becomes OFF, the speed is reduced to 0 rps.
(c) Reset conditions: When either of the following condition is satisfied.
1) The outdoor air temperature is lower than 40ºC or 46ºC.
2) The compressor command speed is 0 rps.
(3) Cooling high pressure control
(a) Purpose: Prevents anomalous high pressure operation during cooling.
(b) Detector: Outdoor heat exchanger sensor (TH1)
(c) Detail of operation:
(Example) Fuzzy
Notes (1) When the outdoor heat exchanger temperature is in the range of 58~63 ºC, the speed is reduced by 6 rps at each 30 seconds.
(2) When the temperature is 63 ºC or higher, the compressor is stopped.
(3) When the outdoor heat exchanger temperature is in the range of 53~58 ºC, if the compressor command speed is been maintained and the operation has
continued for more than 30 seconds at the same speed, it returns to the normal cooling operation.
(4) Cooling low outdoor temperature protective control
(a) Operating conditions: When the outdoor air temperature (TH2) is 22ºC or lower continues for 20 seconds while the
(b) Detail of operation:
1) The lower limit of the compressor command speed is set to 44 (30) rps and even if the speed becomes lower than 44 (30)
rps, the speed is kept to 44 (30) rps. However, when the thermo becomes OFF, the speed is reduced to 0 rps.
2) The upper limit of the compressor command speed is set to 50 (60) rps and even if the calculated result becomes
higher than that after fuzzy calculation, the speed is kept to 50 (60) rps.
Note (1) Values in ( ) are for outdoor air temperature is 22ºC or 25ºC
Upper limit 50 rps
ON
Lower limit 44 rps
A B
more, or 47ºC or more (Models 50, 60: 41ºC or more) with the compressor running, the lower
limit speed of compressor is brought up.
Item
Outdoor air temperature
Lower limit speed
After lapse of 30 sec. or over
After lapse of 30 sec. or over
After lapse of 30 sec. or over
53
Outdoor unit heat exchanger temperature (°C)
compressor command speed is other than 0 rps.
ON
Upper limit 60 rps
Lower limit 30 rps
C D
Outdoor air temp.(°C)
Model
SRF25, 35ZIX-S
41°C or more
30 rps
6rps (1)
(3)
(3) 6rps (1)
lower limit
(3)
speed 30 rps
58
¡ Values of A, B, C, D
OFF
First time
Since the seconds
times
64
- -
SRF50ZIX-S
47°C or more 41°C or more
40 rps
0rps
63
Outdoor air temp. (˚C)
A B C
0 3 22
7 10 25
30 rps
D
25
28