Application guidelines
44
FRCC.PC.023.A7.22
Single compressors
Operating conditions
70
65
60
55
50
45
40
35
30
25
20
15
10
-30
-25
-20
-15
-10
-5
0
5
10
15
20
Cond. temp
. (°C
)
Evap. temp. (°C)
LP1
HP2
HP1
R410A
DGT - limit
Example 1
Example 2
LP2
Example 1
(R410A, SH = 6 K)
LP switch setting:
LP1 = 3.3 bar (g) (-15.5°C/4.1°F)
HP switch setting:
HP1 = 38 bar (g) (62°C/143.6°F)
Risk of operation beyond the application envelope.
DGT protection required.
Example 2
(R410A, SH = 6 K)
LP switch setting:
LP2 = 4.6 bar (g) (-10.5°C/13.1°F)
HP switch setting:
HP2 = 31 bar (g) (52°C/125.6°F)
No risk of operation beyond the application envelope.
No DGT protection required.
Discharge gas thermostat
Discharge gas temperature (DGT) protection
is required if the high and low pressure switch
settings do not protect the compressor against
operations beyond its specific application
envelope. Please refer to the examples below,
which illustrate where DGT protection is required
(Ex. 1) and where it is not (Ex. 2).
Discharge gas temperature
protection function
A discharge temperature monitor function can be
enabled in the frequency converter. All settings
are available in parameter list 28.2x, they are
factory preset as follow:
• 28.20: [0] none - temperature source (sensor
input)
• 28.21: [60] °C - temperature unit
• 28.24: 130 - warning level
• 28.25: [1] decrease cooling - warning action
• 28.26: 145 - emergency level
• 28.27: is the actual discharge temperature
measured by the sensor.
To activate the discharge temperature monitor
function, with the factory setting, the only
modification required is to connect the sensor
to Analog Input 54 (4 - 20 mA) between 13 and
54, and set the parameter 28.20 to “[2] Analog
input 54”. When the warning level is reached
“decrease cooling” action starts by decreasing
the compressor speed by steps of 10 rps(600rpm)
every 3 minutes until the temperature, either
drops below the level, programmed in parameter
28.24 (warning level) or exceed the level
programmed in parameter 28.26 (emergency
level). When the emergency level is reached,
the compressor is stopped and the frequency
converter shows an “alarm”.
