Mitsubishi Heavy Industries SCM71ZM-S1 Technical Manual page 197

(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
(b) Detail of operation:
(i) The lower limit of compressor command 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 thermo becomes OFF, the speed is reduced to 0 rps.
(ii) The upper limit of compressor command speed is set to A or C rps, the speed is kept to A or C rps.
Values of A ~ D
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 command speed is 0rps.
(4) Heating high pressure control
(a) Models SCM71, 80
(i) Starting condition: When the indoor heat exchanger temperature (Th2) has risen to a specified temperature while
(ii) Compressor command speed is controlled according to the zones of indoor heat exchanger tem-
perature as shown by the following table.
Protection control speed (NP)
Sampling time (s)
• Models SCM71, 80
NP
<
10 = NP < 90
<
90 = NP < 100
<
100 = NP < 110
<
110 NP < 120
=
<
120 NP
=
compressor command speed is other than 0 rps.
ON
Upper limit C rps
Lower limit D rps
0 3
Outdoor air temperature(°C)
Model
SCM71ZM-S1 SCM80ZM-S1
75 rps 75 rps
30 rps 30 rps
60 rps 60 rps
40 rps 40 rps
the compressor is turned on.
Th2 < P1 P1
Normal
Normal
Th2
P1 P2
45 52
45 – 44.5 52 – 49.5
44.5 – 44 49.5 – 47.5
44 – 43 47.5 – 45
45
43
ON
Upper limit A rps
Lower limit B rps
22 25
< <
Th2 < P2 P2 Th2 < P3
= =
Retention NP–4rps
20 20
Unit: °C
P3
57
57 – 54
54 – 51
51 – 48
48
196
- -
'17 • SCM-T-225
OFF
<
P3 Th2
=
NP–8rps
20