CSZ EZT-570i, Техническое руководство

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EZT-570i Technical Manual
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4.3 Auxiliary Cooling System
The auxiliary cooling system can be installed as a boost system or a low range control system. When
set as a boost, it will assist the refrigeration system in lowering chamber temperatures quickly. As a
control, it will take over once the low temperature limit of the refrigeration system is reached and
continue cooling the chamber down to an ultimate low of the auxiliary cooling medium (LN2 or CO2).
Auxiliary Cool Boost Operation
When the auxiliary cooling option is set for boost in the configurator, the auxiliary cooling supply valve
output (Q36) will turn on when the chamber and auxiliary cooling events are enabled. The EZT will
then monitor the cooling percentage of output. When it exceeds the auxiliary cooling on percentage
set point for the on delay time period, the boost cool output (Q37) will turn on. When the percentage
of output drops below the on percentage set point, the output will turn off. The supply valve output
will remain on as long as the event is on. Only the boost output will cycle on and off for control.
Once the air temperature reaches the low limit set point in the configurator (boost cool disable), the
boost cooling output will be disabled to prevent the chamber from going colder than what the
refrigeration system is capable of in order to protect the compressors.
Auxiliary Cool Control Operation
When auxiliary cooling is set for control in the configurator, the auxiliary cooling system will operate
according to the boost control logic until the low limit set point is reached. The low limit set point in
the configurator (boost cool disable) is the lowest safe operating range for the refrigeration system.
Once the low limit set point temperature is reached, the refrigeration system is shut down and the
minimum heat/cool output (Q41) is disabled. This transfers the cooling output from the 9300
controller to the auxiliary cooling control solenoid. This allows the chamber to be controlled to
temperatures below what the refrigeration system can produce.
4.3.1 Auxiliary Cooling System Failures and Corrective Actions
SYMPTOM PROBABLE CAUSES CORRECTIVE ACTIONS
Boost cooling not turning on.
Auxiliary cooling event not turned on.
Loop percentage of output not
exceeding on percentage for delay
period.
Air temperature at minimum allowable
range.
Altitude system on (altitude chambers).
Turn on auxiliary cooling event.
Check loop output percentage, adjust
configurator settings if necessary for
performance.
Chamber at low limit. Can not go any
colder.
Turn off altitude system.
Poor cooling performance with
auxiliary cooling on.
Cooling medium (LN2/CO2) not
reaching chamber as liquid.
Supply/control valve clogged/failed.
Allow boost cooling to run longer in
order for liquid to reach chamber.
Insulate supply lines.
Install automatic purge system to
bleed off gas in order to maintain
liquid in supply line.
Inspect valve. Clean/Replace if
necessary.