• Unit reset procedure is as described in the previous table (above).
[Note: Unit lock-out can activate a telephone dialer and buzzer plus signal on the LED’s of
the Diagnostic Module (option), if this option is available on your unit.]
To satisfy the Low Pressure Pump Down Control function, an Adjustable Low Pressure Switch
is provided as an Option and will be fitted in the Unit if this option is selected.
12.4 Compressor Discharge Temperature Protection
Abnormally high discharge line temperatures can damage the scroll sets as well as the
compressor motor. The ZX employs a patented liquid injection that injects liquid refrigerant into
the suction line as previously described .
Activation of the liquid injection valve is in response to a thermistor inserted into a pocket located
in the top of the scroll compressor . The E2 takes this signal and converts it into a signal to the
stepper motor of the injection valve, opening the valve linearly in response to increasing discharge
temperatures and injecting liquid refrigerant directly into the suction line, reducing the discharge
temperature.
12.5 Other Inputs to the E2 Board
12.5.1 Customer Supplied Control (Thermostat)
The E2 accepts a normal 220 volt AC input ON/OFF signal (such as the switching action of a
normal commercial thermostat and relays a similar action as an output to the compressor
contactor (refer to the wiring diagram in the Addendum section) in the case of thermostat
controlled system. If the system is controlled by Low Pressure Cut Out for a Multiple Evaporator
system and/or Pump Down system, the E2 accepts signal directly from an Adjustable Low
Pressure Switch ( Option )
12.5.2 Case Temperature Thermistor
An alternative method of system temperature control can be used. The E2 accepts an input
from a common commercial thermistor, This sensing device is fixed inside the indoor load (e.g.
refrigerated display case). The sensor has a range of between-40and+80C and normally operates
in the range of –10 to +3C. The sensor cable can be a maximum of 10 metres in length. In this
case, the Defrost Module (Option) to can combine to provide cost effective case control.
Fig 19 . E2 Control Reference Guide
37
Failure/Incident Type Setting E2 Reaction Reset Procedure
(E2 Event in brakets 7 ithalics - refer to Fig 6)
Hi
h Pressure Cut-Out
Contact Open 2.8 +/- 0.1 Mpa Execute Stop Program and after 3 minutes run Within 1 hour 5 auto
Contact Close 2.1 +/- 0.07 Mpa Normal Start Program to restart the CDU resets are allowed
On the 6th request for reset, HP Error is set and system
will be locked out and the Diagnostic LEDs will light-up
(HP Cut-Out)
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