Emerson ZX User Manual page 33

The function of the E2 is to react to the ON/OFF signals it receives from these devices (i.e.;
thermostat), to operate and protect the ZX unit. The E2 control panel is fitted as standard and has
been developed along with the ZX compressor to provide the following control and protection
systems :
Automatic Liquid Injection:
suction line of the scroll compressor to reduce discharge temperatures generated when the unit
operates at increasing compression ratios. The E2 controller reacts automatically to a thermistor
embedded in a pocket inserted into the top of the ZX compressor .The controller converts this
signal for the linear stepper motor driving the liquid injection valve to a position that enables the
compressor to continue operating within its safe envelope. This advanced control strategy
extends the operating range and is not normally associated with a standard refrigeration
condensing unit of this size making this feature a clear point of differentiation the competition.
Base Controller
The E2 is also the
functions such as:
Main load controller ( or Thermostat).
Evaporator electric defrost heater contactor.
Evaporator fan contactor.
Copeland supplied Option - Liquid Line Solenoid Valve ( supplied loose for fitting
external to the ZX unit).
Copeland supplied Option - Fan Speed Control.
This option automatically controls fan speed and is useful where low ambient
temperatures are experienced – such as might cause a loss of case/cool room
temperatures and control. Low ambient temperatures reduce the condensing
pressures to such low levels that there is insufficient pressure drop across the
expansion device to force the liquid refrigerant through the orifice. As we know, liquid
refrigerant being forced through the orifice is what causes part flashing of the
refrigerant and brings the liquid refrigerant to design evaporating pressures ( and
temperatures ) . Control is via the E2 panel , a modified E2 Micro-Controller – with the
Fan Control logic built-in and two additional sensors ( condenser coil and ambient
sensors) are added
Copeland supplied option - Diagnostic Module. The option provides the ZX with a
self diagnostic function, signaling individual component failure in three ways:
(a) visible LED combination ( as mentioned earlier)
(b) remote audible buzzer , and
(c) a dialer connection for the purpose of sending a common fault signal
The E2 automatically injects cool liquid refrigerant into the
for the connection of many optional and customer supplied
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