Cooling Low Outdoor Temperature Protective Control; Heating High Pressure Control - Mitsubishi Heavy Industries SCM50ZS-S1 Technical Manual

(3) Cooling low outdoor temperature protective control

(a) Operating conditions
When the outdoor air temperature (Tho-A) is 22°C or lower continues for 20 seconds while compressor speed is other than 0 rps.
(b) Detail of operation
(i) The lower limit of compressor speed is set to B or D rps and even if the speed becomes lower than B or D rps, the
speed is kept to B or D rps. However, when the thermostat OFF, the speed is reduced to 0 rps.
(ii) The upper limit of compressor speed is set to A or C rps, the speed is kept to A or C rps.
・ Values of A-D
Model
A
B
C
D
(c) Reset conditions
When the either of the following conditions is satisfied.
(i) When the outdoor air temperature (Tho-A) becomes 25°C or higher.
(ii) When the compressor speed is 0rps.

(4) Heating high pressure control

(a) Starting condition
When the indoor heat exchanger temperature (Th2) has risen to a specified temperature while the compressor is turned on.
(b) Operating condition
Compressor speed is controlled according to the zones of indoor heat exchanger temperature as shown by the following table.
Protection control speed (NP)
Sampling time (s)
・Model SCM50
Th2
NP
<
10 = NP < 115
<
115 = NP < 120
<
120 NP
=
・Model SCM60
Th2
NP
<
10 NP < 90
=
<
90 NP < 120
=
<
120 = NP
ON
Upper limit C rps
Lower limit D rps
0 3
Outdoor air temperature(°C)
SCM50 SCM60
75 rps 75 rps
35 rps 30 rps
60 rps 60 rps
45 rps 40 rps
<
Th2 < P1 P1 Th2 < P2
=
Normal Retention
Normal 20
P1 P2 P3
45 52 56
45 – 43 52 – 50 56 – 54
54
43 50
P1 P2 P3
45 52 56
45 – 43 52 – 45 56 – 48
48
43 45
187
-
ON
Upper limit A rps
Lower limit B rps
OFF
22 25
< <
P2 Th2 < P3 P3 Th2 < P4
= =
NP–4rps NP–8rps
20 20
Unit: °C
P4
58
58
58
Unit: °C
P4
58
58
58
-
'18 • SCM-T-251
<
P4 Th2
=
NP ＝ 0
Normal