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STRATUS TA20 Series Industrial Air Conditioners User Manual
1st edition RevA.
System Operation
Once the STRATUS system has been installed onto the
enclosure and the power has been connected to a properly
grounded power source with adequate voltage and current
supply, the unit is ready for operation. As soon as electrical
power is supplied to the STRATUS system and the power
switch located on the back of the unit is turned on, the
evaporator fan will start to operate. The fan will run
continuously so that the controller can monitor the enclosure’s
internal temperature. The enclosure temperature will be
displayed on the face of the controller. If the enclosure
temperature is greater than the cooling setpoint of 95°F plus
factory-set temperature differential of 5°F, the snowflake status
LED will be ON and the compressor will turn on. After the
refrigerant pressure builds up to a factory setpoint of 300 psi,
the condenser fan will operate.
This signifies that the cooling system has begun operation to
remove heat and humidity from the enclosure. If the heat
load within the enclosure is less than the cooling capacity of
the STRATUS system, the temperature on the digital display
will begin to drop. When the temperature inside the enclosure
drops to the factory-set 95°F setpoint, the compressor will
cycle off. The cool air evaporator fan will continue to operate,
circulating air within the enclosure. The compressor fan will
cycle off if the pressure drops below the factory setpoint.
Example: “Cooling on” @ 100°F; “Cooling off” @ 95°F.
Set point is 95°F plus 5°F Hysteresis= Cooling on @ 100°F.
If the compressor attempts to cycle within 5 minutes, the
snowflake status LED will FLASH. This indicates that the
compressor’s automatic timer is working (the anti-short-cycle
timer is factory set at 5 minutes). At the end of 5 minutes, the
compressor will begin to operate and the snowflake status LED
will remain ON while the compressor remains on.
System Faults
If any of the critical control parameters exceed limits, the
compressor is turned off, an alarm condition is indicated on the
front panel, and an alarm contact operates for remote alarming.
Three main conditions can shut down the AC compressor:
• The condenser high temperature alarm
• The evaporator coil alarm
• The compressor thermal overload
In the event that the condenser coil overheats, a condenser high
temperature alarm,
HA2
, will flash on the display of the digital
temperature controller, the remote alarm contact will operate,
and the compressor will turn off after a 3-minute time delay.
In the case that the evaporator coils ice up or there is a leak,
an evaporator coil alarm,
CA
, will flash on the display of the
Digital Temperature Controller, the remote alarm contact will
operate, and the compressor will turn off after a 2-minute time
delay.
A thermal overload protects the compressor against faults. In
the event that the snowflake status LED is not flashing on the
display and the compressor is not running, an internal fault
may have occurred on the unit. Refer to the Troubleshooting
Guide in this manual.
Alarm Conditions
If any of the alarm parameters exceed limits, an alarm condition
is indicated on the front panel and an alarm contact operates
for remote alarming.
The temperature alarms are delayed for 30 minutes at initial
startup. If the preset high temperature limit is exceeded for
more than 3 minutes, the compressor continues to operate but
there is a maximum temperature alarm,
HA
, flashing on the
display.
If the preset low temperature limit of 45°F is exceeded for
more than 3 minutes, there is a minimum temperature alarm,
LA
, flashing on the display. (The compressor turns off at the
temperature setpoint.)
In case of a fault in the enclosure temperature probe “P1”,
the start and stop of the compressor are delayed for 5 and 15
minutes, respectively. A
P1
alarm will display and the remote
alarm contact will operate immediately.
In case of a fault in the condenser temperature probe “P2”, a
P2
alarm will flash on the display and the remote alarm contact
will operate immediately.
If the evaporator coil pressure drops below 10 psi for more
than 2 minutes, there is an evaporator coil alarm,
CA,
and the
compressor turns off. After the pressure is increased to 25 psi,
the
CA
alarm is cleared and the compressor operates after a
5-minute time delay.
Time
Temperature
Compressor
SET
ON
