12 C6.1.6/0117-1017/E
▪ ZXLE & ZXME units: 28 bar cut-out / 21 bar cut-in.
▪ ZXDE units: 28.8 bar cut-out / 24 bar cut-in.
Adjustable high pressure limitation: The unit controller provides the possibility to stop the unit at
a required discharge pressure which is lower than the cut-out value of the fixed high-pressure switch.
Detailed instructions can be found in chapter 2.9.4 "Additional features for customization" hereunder.
Discharge temperature protection: Each unit is equipped with a discharge line sensor (NTC). The
information from the NTC sensor is used to activate liquid injection when required. The XCM25D
controller will stop the compressor if discharge temperatures reach unacceptable levels.
Adjustable low pressure alarm (from S/N 16EZ08855M onwards): The unit controller features an
adjustable low pressure alarm managed by the suction pressure sensor. The factory setting of this
alarm is the lowest permitted pressure of the refrigerant with the lowest pressure-vapour properties.
If needed the user can modify this value according to the required application.
▪ ZXME & ZXDE units: 0.5 bar rel
▪ ZXLE units: 0.1 bar rel
In case of very low cut-out pressure on ZXLE units it is possible that the suction pressure will get
lower than 0.1 bar rel due to the 5-second switching off delay. In this case the user can deactivate
the low-pressure alarm with parameter D13 or activate the alarm delay with parameter D12.
Option: Adjustable low-pressure switches PS1: This device protects the system against low
pressure operation. It must be adjusted depending on running conditions and potential special
requirements like pump-down. The compressor envelopes published in Select must be respected at
all times. In case of controller breakdown, the low-pressure switch could be used for emergency
operation (rewiring required).
A crankcase heater is directly connected to the controller. The crankcase heater will be energized
when the ambient sensor is below a given value (10°C) and the compressor has been off for a period
of time (5 minutes). The minimum off time does not apply at initial power up.
In addition to the above, the ZX condensing unit has the following features:
▪ Liquid line assembly (filter drier and sight glass/moisture indicator)
▪ Anti-corrosion treatment to the condenser fins
The electronic controller is also the base controller for the connection of many optional and customer
supplied functions such as:
▪ Main load controller (or thermostat)
▪ Evaporator electric defrost heater contactor
▪ Evaporator fan contactor
▪ Superheat controller for one electronic expansion device (not available on ZXLE units)
2.9.4 Additional features for customization
A lot of additional features are provided by the XCM25D controller. In the European design of the
electrical panel a few of the additional functionalities are prearranged and can easily be installed by
connecting additional hardware to the electrical terminals. The tables in Appendix 7 show the
parameters that have to be changed in case a special feature of the controller should be activated.
The tables do not show the required settings which have to be done by the system operator, eg,
choosing correct setpoints for different components and different applications.
NOTE: After programming an additional function, the system will have to be restarted. To
engage system restart, switch off the main power supply, wait for 5 seconds and switch it on
again.
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