Compressor Motor Protection; System Pressure Protection; Other Inputs Of The Xcm25D Controller; Customer-Supplied Control (Room Thermostat) - Emerson Copeland EazyCool ZX Series Application Manuallines

2.18 Compressor motor protection

The electronic controller protects the compressor motor against the following:
▪ overcurrent;
▪ phase loss;
▪ incorrect phase rotation;
▪ voltage imbalance.
If the compressor motor current exceeds a predefined (non-adjustable) current limit, the electronic
controller shuts the unit down and generates an error signal. For this function two of the main phase
supply lines to the compressor (compressor via the contactor) are routed through the current
sensors.

2.19 System pressure protection

A high-pressure safety switch is registered by the electronic board. The sensing device is a non-
adjustable, high-pressure switch that will open in the event of an abnormally high discharge pressure
(above 31 bar on both ZXMY and ZXDY units).
▪ The unit will stop then and restart automatically after a 5-minute delay and after unit pressure has
decreased to 22 bar.
▪ After 7 successive HP cut-outs over 1 hour, the unit will lock out. In this case a manual reset will
be necessary.

2.20 Other inputs of the XCM25D controller

2.20.1 Customer-supplied control (room thermostat)

The XCM25D electronic controller uses a digital input (DI3) open/close signal (such as the switching
action of a normal commercial thermostat) and relays a similar action as an output to the compressor
contactor in the case of a thermostat-controlled (parameter "C05") system – see wiring diagrams in
Appendices 2 and 3. If the system is controlled by low-pressure cut-out for a multiple evaporator
system and/or pumpdown system, the controller accepts signals directly from an adjustable low-
pressure switch (optional).

2.20.2 Case temperature controller

An alternative method of system temperature control can be used. The electronic controller accepts
an input from a common commercial thermostat (DI3, digital input). For details see Chapter 2.10.5
"Additional features for customization".

2.20.3 Ambient temperature sensor

An ambient temperature sensor is connected to the electronic controller. This temperature sensor
has several functionalities like emergency mode control, lower fan speed limitation and crankcase
heater control. The sensor is located on the backside of the compressor compartment.

2.21 Alarm output (DO5) of the XCM25D controller

The digital output DO5 is pre-configured as an alarm contact. The relay (max. 5 A, 250 VAC) is
activated in case of alarms and lockouts. Warnings will be shown only on the controller display.
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