CSZ EZT-570i, Техническое руководство

Страница: 51 / 95

EZT-570i Technical Manual
51
motor windings have overheated (if equipped). This input is
active low, i.e., the input must be off in order for the alarm to be
indicated. When active (input off), the EZT shuts down the
chamber until the alarm is acknowledged (silence button pressed
on alarm monitor screen) and the input is on (automatically
resets after built-in timeout period).
Sys1 Defrost Pressure Switch (I40): This input is a control input for defrost (if equipped). There is no
user indication for this input. When equipped with defrost, this
input is wired to a pressure switch on the discharge of system 2
compressor. This input is used to control system 1 cooling of
system 2. When the input is on, system 1 will cool the cascade
condenser for system 2. When the input is off, the EZT turns off
cooling to the cascade by either turning of the cascade cooling
solenoids (Q43) for large HP defrost or by turning off system 1
compressor for standard defrost.
Sys1 Defrost Thermostat (I41): This input is a control input for defrost (if equipped). There is no
user indication for this input. When equipped with defrost, this
input is wired to a thermostat on the suction line of the cooling
coil. When the refrigeration system is in defrost, this input is
used to begin the termination sequence for defrost by signaling
that the coil defrost temperature has been met.
When the input first turns on, the EZT will begin the 15 minute
countdown to terminate defrost. The thermostat is typically set
for about 10°C (50°F). After defrost times out, the prechill step
begins. The refrigeration system will begin to cool the coil.
Once the thermostat sees the coil drop below the set point, a 60
second prechill timer will begin. At the end of 60 seconds, the
chamber will return to normal operation.
If the control loop is not calling for 100% cooling, the prechill
timer will begin its 60 second countdown regardless of the
suction line temperature.
Door Switch (I42): The door switch input is used to indicate if the chamber door is
open or closed (if equipped). The "door ajar" status will be
displayed on the system status monitor screen. If the door
control option is enabled, the EZT will shut down the chamber
when the door is opened. This input is active low, i.e., the input
is off to indicate an “open door” status.
If the door alarm option is enabled, a “door open” alarm will
appear on the alarm monitor screen and the audible alarm will
sound if the door is open when the chamber is running.
Emergency Stop (I43): The emergency stop input is used to indicate that the emergency
stop has been activated (if equipped). This input is active high,
i.e., the input must be on in order for the alarm to be indicated.
When active (input on), the EZT shuts down the chamber until
the alarm is acknowledged (silence button pressed on alarm