Frost Prevention Control; Dew Prevention Control - Mitsubishi Heavy Industries SRK100VNXPZSX Technical Manual

(12)

Frost prevention control

(a) Operating conditions
1)
2)
(b) Detail of anti-frost operation
Indoor heat exchanger
Item
Lower limit of compressor command speed
Indoor fan
Outdoor fan
4-way valve
(c) Reset conditions
1)
2)
(c) Cooling overload protective control
(13) Dew prevention control (During cooling or dehumidifying)
(i) Operating conditions
Prevents dewing on the indoor unit.
When the outdoor air temperature (TH2) has become continuously for 30 seconds at 38°C or more, or 41°C or more, or
(a) Operating conditions
47ºC or more with the compressor running, the lower limit speed of compressor is brought up.
When the following conditions have been satisfied for more than 30 minutes after starting operation
1) Compressor's speed is 22 rps or higher.
Item
2) Detected value of humidity is 68% or higher.
Outdoor air temperature
(b) Contents of operation
Lower limit speed
1) Air capacity control
(ii) Detail of operation
1) The outdoor fan is stepped up by 3 speed step. [Upper limit 8 th speed.]
Item
2) The lower limit of compressor speed is set to 25 or 30 or 40rps.
However, when the thermo OFF, the speed is reduced to 0 rps.
ULO
(iii) Reset conditions
AUTO, LO
Twin
1)
type
ME
2)
HI
(d) Cooling high pressure control
(i) Purpose
ULO
Prevents anomalous high pressure operation during cooling.
(ii) Detector
AUTO, LO
Outdoor heat exchanger sensor (TH1). Triple
type
(iii) Detail of operation
ME
(Example) Compressor speed
HI
Note (1) Ranges A and B are as shown below.
Range A
P1
Outdoor heat exchanger temperature (°C)
Notes (1) When the outdoor heat exchanger temperature is in the range of P2-P3 , the speed is reduced by 8 rps at each 20 seconds.
(2) When the temperature is P3
(3) When the outdoor heat exchanger temperature is in the range of P1-P2
more than 20 seconds at the same speed, it returns to the normal cooling operation.
temperature 5°C or lower
25 rps
Depends on compressor speed
Model
SRK20, 25, 35ZSX-S
38°C or more
25 rps
Upper limit of compressor's speed
Indoor fan
Upper limit of compressor's speed
Indoor fan
37°C (models SRK50, 60 : 40°C).
Upper limit of compressor's speed
Indoor fan
Upper limit of compressor's speed
Indoor fan
Upper limit of compressor's speed
Indoor fan
Upper limit of compressor's speed
Indoor fan
Upper limit of compressor's speed
Indoor fan
Upper limit of compressor's speed
After lapse of 30 sec. or over (3)
Indoor fan
After lapse of 30 sec. or over (3)
After lapse of 30 sec. or ove r (3)
Range B
68 73
Humidity(%)
or higher, the compressor is stopped.
-
2.5°C or lower
Keep the fan speed before
frost prevention control
2.5–5
5–8
SRK50, 60ZSX-S
41°C or more
30 rps
Model
RangeA: 30 rps, RangeB: 24 rps
RangeA: 40 rps, RangeB: 24 rps
Adaptable to compressor speed
RangeA: 50 rps, RangeB: 30 rps
Adaptable to compressor speed
RangeA: 50 rps, RangeB: 30 rps
Adaptable to compressor speed
RangeA: 30 rps, RangeB: 24 rps
RangeA: 50 rps, RangeB: 24 rps
Adaptable to compressor speed
RangeA: 50 rps, RangeB: 30 rps
Adaptable to compressor speed
RangeA: 70 rps, RangeB: 30 rps
8rps (1)
Adaptable to compressor speed
8rps
(1)
lower limit
speed 30rps
0rps
P2 P3
, if the compressor speed is been maintained and the operation has continued for
71
-
'09•SRK-DB-087D
'17 • PAC-T-257
compressor
speed
Lower
limit
speed
0 rps
2.5
Indoor heat exchanger
temperature (°C)
47°C or more
40 rps
SRK50, 60ZSX-S
4th speed
4th speed
Range B
Range A
31 32
Outdoor air tamperature(
5 8
)