Controller Ca Control - Carrier 69NT40-489-100 Series Operation And Service Manual

CODE
NO.
AL41 O Gas Calibration Failure
2
AL42 O Air Calibration Failure
2
AL43 Not used
AL44 Not used
AL45 Alarm List Failure
AL46 Alarm List Full
AL47 Pressure Sensor Failure
AL48 Oxygen Sensor Voltage Failure
AL49 Drain Valve Failure

9.1.7 Controller CA Control

WARNING
Low oxygen levels inside container. Venti-
late container before entering. Stay away
from doors while venting.
The CA Controller controls the percentages of oxygen
and carbon dioxide inside the refrigerated container.
The level of oxygen and carbon dioxide in the container
is lowered by replacing them with nearly pure nitrogen
generated by the system. The level of these gases is
increased by energizing respective solenoids when
required; allowing compressed outside air to flow into
the container (for oxygen); and 100% carbon dioxide to
flow into the container from an external source provided
by the user.
Before the CA system can start, certain conditions of the
refrigeration system must be met (refer to section
10.2.a., page 111). If all these conditions are met, the
Temperature (refrigeration) Controller enables CA.
Once the oxygen sensor detects an oxygen level
BELOW 19.8%, the CA Controller closes the door
interlock switch to prevent anyone from entering the
hazardous atmosphere of the container.
T-305
TITLE DESCRIPTION
Alarm 41 is triggered by an unsuccessful calibration attempt.
This alarm will remain active until a successful calibration is
performed.
Alarm 42 is triggered by an unsuccessful calibration attempt.
This alarm will remain active until a successful calibration is
performed.
Alarm 45 is triggered by an error in the CA Controller involving
the alarm queue. This is a display alarm and has no
associated failure action.
Alarm 46 is set whenever the alarm list is determined to be
full; at start-up or after recording an alarm in the list. AL46 is
displayed, but is not recorded in the alarm list. This alarm can
be reset by clearing the alarm list. This can only be done if all
alarms written in the list are inactive.
Alarm 47 is triggered by a pressure reading outside of the
range between 20 psi and 200 psi after the air compressor
has been running for more than 30 seconds. This is a display
only alarm and will remain active until the pressure is in range
or the system is reset.
Alarm 48 is triggered by an oxygen sensor output voltage less
than 15 mv, or greater than 4.1 v. This alarm will remain active
until the sensor is in-range. While AL48 is active, the
compressor will run with the oxygen solenoid valve (OSV)
open, unless AL39 is active, whereby all control units will be
disabled, except the sample air solenoid valve (SAV).
Alarm 49 is triggered by the controller detects pressure
differential greater than 15 psig from the starting pressure of
50 psig. This is a display only alarm and will remain active
until the pressure is in range or the system is reset.
When the CA Controller starts, air from outside the
container enters the air compressor via the air intake
filter. The air compressor is protected by an internal
temperature switch (IP-AM) that sends a signal to the
CA Controller if it reaches an unsafe operating
temperature. The ambient air entering the air
compressor is compressed. This pressurized air is then
filtered by a membrane air filter assembly that removes
dirt and moisture before it enters the air heater (AHTR).
The first stage of the air filter removes large particulates
and moisture. The second stage employs a coalescing
feature to remove the remaining moisture and fine
particulates. Each stage is equipped with a normally
closed drain solenoid valve (DS1 & DS2). The CA
Controller energizes those drain solenoid valves for 10
seconds every one-half hour to remove residue
accumulated by the filters.
The filtered pressurized air moves to the air heater,
where it is heated to operating temperature, for use in
the nitrogen membrane separator. The CA Controller
monitors the membrane temperature sensor (MTS) to
control the operation of the heater, which maintains the
temperature of the compressed air entering the nitrogen
membrane separator. The high air temperature switch
(HATS) is installed to prevent overheating of the
membrane.
The heated, pressurized air enters the membrane,
where the nitrogen is separated out. The purified
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