Electronic Board Control And Operating Features; Electronic Board Features - Emerson Copeland EazyCool ZX Series Manual

2.8

Electronic board control and operating features

The function of the electronic board is to react to the On/Off signals received from devices such
as thermostat to operate and protect the ZX unit. The electronic board control panel is fitted as
standard and has been developed along with the compressor to provide the following control
and protection systems:

2.8.1 Electronic board features

Automatic liquid injection: The electronic board automatically injects cool liquid refrigerant into
the suction line of the Scroll compressor to reduce discharge temperatures generated when the
unit operates at increasing compression ratios. The electronic board controller reacts
automatically to a thermistor embedded in a pocket inserted into the top of the 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 from the competition.
Compressor phase reversal: Ensures that the compressor remains running in one direction
only – necessary for a compliant Scroll compressor to compress and pump refrigerant. Reset is
automatic once the phase rotation is correct for the compressor.
Motor current overload protection is provided (also via the electronic board) eliminating the
need for external current protection for the compressor motor.
Fixed low- and high-pressure switches: These are non-adjustable protection devices to
prevent the compressor operating outside of its safe evaporating and condensing pressure
ranges. Reset is automatic for a set number of trips, and then the unit will lock out and require
manual restart. The latter feature is important to prevent the ZX unit cycling under these controls
for a long period of time.
A crankcase heater is wired through a normally closed contact of the compressor contactor in
the usual manner, becoming energized whenever the compressor cycles off.
In addition to the above, the ZX has the following features:

Liquid line assembly (filter drier and sight glass/moisture indicator) - fitted

Anti corrosion treatment to the condenser fins - supplied as standard

Adjustable LP switch for low-pressure pump down control - fitted
The electronic board 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

Diagnostic module: This option provides the ZX with a self-diagnostic function, signalling
individual component failure in three ways:
(a) Visible LED combination
(b) Remote audible buzzer
(c) A dialer connection for the purpose of sending a common fault signal through
a telephone service to a remote location.
C6.1.6/1108-0509/E 5