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short time. If this occurs more than three times within an hour the compressors are blocked. Before a low-
pressure fault is triggered a low-pressure warning is signalled.
4.5.5.
Fan speed control
Due to the continuous adjustment in the number of fans, the condensing pressure is kept constant depending
on the ambient temperature by means of a PI controller. As the condensing pressure at the moment in which
the compressor is switched on rises very fast, the PI controller is superimposed by a P controller with limiting
setpoint. This only intervenes if the PI controller is too slow.
4.5.6.
Electronic expansion valve control
An electronic expansion valve with PI controller is used to keep the overheating constant. To prevent the
maximum operating pressure (MOP) from being exceeded, a P controller is used, which counteracts when
the MOP is approached and limits opening of the electronic expansion valve.
4.5.7.
Temperature limit monitoring
The temperature of the cold water feed is monitored for a minimum and maximum limit value if the chiller is
switched on (pump is running). If the limit value is exceeded or the minimum is not reached, an alarm is
triggered with time delay, which switches off the chiller.
4.5.8.
Group fault alarm
A group fault alarm is triggered if an alarm occurs. All alarms are included in the group fault, but not the
warnings. The group fault signalling relay has a floating changeover contact and is energised in fault-free
operation, in order to ensure wire break monitoring.
4.6.
Execution types
Basically, you can choose between two types of construction:
4.6.1.
ECO mode
The default setting of the Compact-Line provides for operation in ECO mode ("Run" parameter is set to "0").
As a result, the increase in fan speed reduces the condensing pressure to the minimum necessary value in
the respective operating point – the electrical power consumption of the overall system is limited to a
minimum.
4.6.2.
Comfort mode
In case of strict sound emission requirements the fan speed can be reduced to the minimum necessary value
in the respective operating point and sound power level limited to a minimum. To do this the "Run" parameter
must be set to "1". As a result of the lower air flow rate a reduced output of around 3% is to be expected.
The optimised parameter list for your application is enclosed with the unit.
Cleaning
and maintenance work in accordance with
Chapter 10 Service
. Before work is carried out on the
chiller the protective equipment described in
Table 7: Definition of the safety symbols
must be used.
