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13.9 Auxiliary control
Parameter/description
ADVANCED
High Tcond threshold
High Tcond integration time
ALARM CONFIGURATION
High condensing temperature alarm
timeout (High Tcond)
(0= alarm DISABLED)
Auxiliary control can be activated at the same time as main control, and uses
the probes connected to inputs S3 and/or S4.
Parameter/description
CONFIGURATION
Auxiliary control:
1=Disabled;
2=High condensing temperature protection on S3 probe;
3=Modulating thermostat on S4 probe;
4=Backup probes on S3 & S4;
5, 6, 7 = Reserved;
8 = Subcooling measurement;
9 = Reverse high condensing temperature protection on S3
Def.
Disabled
Def. Min.
Max.
UOM
80
20
-60 (-76) 200 (392)
0
800
°C (°F)
s
600
0
s
18000
Tab. 13.j
The integration time is set automatically based on the type of main control.
•
Tab. 13.i
•
For the high condensing temperature protection (only available with
superheat control), an additional pressure probe is connected to S3 that
measures the condensing pressure. For the modulating thermostat function
(only available with superheat control), an additional temperature probe
is connected to S4 that measures the temperature on used to perform
temperature control (see the corresponding paragraph).
The last option (available if “main control” = 1 to 18) requires the installation of
both probes S3 & S4, the first pressure and the second temperature.
Note:
the protector is very useful in units with compressors on board if the aircooled condenser is undersized or dirty/malfunctioning in the more critical
operating conditions (high outside temperature);
the protector has no purpose in multiplexed systems (showcases), where
the condensing pressure is maintained constant and the status of the
individual electronic valves does not affect the pressure value.
To reduce the condensing temperature, the output of the refrigeration
unit needs to be decreased. This can be done by controlled closing of the
electronic valve, implying superheat is no longer controlled, and an increase in
the superheat temperature. The protector will thus have a moderate reaction
that tends to limit the increase in the condensing temperature, keeping
it below the activation threshold while trying to stop the superheat from
increasing as much as possible. Normal operating conditions will not resume
based on the activation of the protector, but rather on the reduction in the
outside temperature. The system will therefore remain in the best operating
conditions (a little below the threshold) until the environmental conditions
change.
Note: if only one backup probe is fitted, under the manufacture
parameters, the probe thresholds and alarm management can be set
separately.
T_EVAP
HITCond protection (high condensing temperature)
The functional diagram is shown below.
MOP_TH
MOP_TH - 1
C
MOP
t
ON
OFF
L
P
EVD
evolution
t
ON
OFF
CP
S1
S2
S3
F
PID
S
ALARM
t
ON
OFF
M
D
E
V
EEV
P
t
Fig. 13.h
T
Key:
T_COND
HiTcond
PID
D
Fig. 13.g
Key:
CP
C
L
F
S
Compressor
Condenser
Liquid receiver
Dewatering filter
Liquid indicator
EEV
V
E
P
T
Electronic expansion valve
Solenoid valve
Evaporator
Pressure probe (transducer)
Temperature probe
•
•
For the wiring, see paragraph “General connection diagram”.
Condensing temperature
T_COND_TH HiTcond: threshold
High Tcond protection status HiTcond
ALARM Alarm
PID superheat control
t
Time
Alarm timeout
Note:
the High Tcond threshold must be greater than the rated condensing
temperature of the unit and lower then the calibration of the high pressure
switch;
the closing of the valve will be limited if this causes an excessive decrease
in the evaporation temperature.
As already mentioned, the HITCond protection can only be enabled if the
controller measures the condensing pressure/temperature, and responds
moderately by closing the valve in the event where the condensing
temperature reaches excessive values, to prevent the compressor from
shutting down due to high pressure. The condensing pressure probe must be
connected to input S3.
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“EVD Evolution TWIN” +0300006EN - rel. 2.4 - 15.02.2015