Thermo King CRR-40 119, Руководство пользователя

Страница: 59 / 170

MP-3000a Controller
59
NOTE: When the setpoint appears in the
LED display, both the Return and Supply
LEDs are lit.
• The LED then shows the controlling air sensor
temperature.
• The controller senses the incoming power
phase and selects the correct power phase to
unit components.
• The evaporator fan motors start about 40
seconds after the unit was turned ON.
• - Evaporator fans operate on high speed at
setpoints of -9.9 C (14.1 F) and above.
• - Evaporator fans operate on low speed at
setpoint temperatures of -10 C (14 F) and
below.
• About 10 seconds later, the compressor starts
and the liquid line solenoid energizes (opens)
if the controller calls for cooling.
• The condenser fan then starts if the Condenser
Fan switch is in the FAN AIR position and the
condenser temperature requires condenser fan
operation.
• If the controller calls for heating, the electric
heaters are pulsed On and Off to provide heat.
• The controller turns ON the In-range LED
when the con-trolling sensor temperature is
within 1.5 C (2.7 F) of the setpoint.
NOTE: If the compressor has been off for
more than 18 hours, the controller performs
a compressor sequence start. See
“Compressor Sequence Start” in this chapter
for further details).
NOTE: Random time delays during the
initial unit start-up minimize peak current
draw.
Continuous Temperature
Control Operation
Chill Loads — Controller Setpoint at
-9.9 C (14.1 F) and Above
The controller regulates the compressor, KVQ
valve and electric heaters based on a Control
Temperature Differential (see “General Theory of
Operation” in this chapter for more detail). This
means the unit operating mode can NOT be
predicted based ONLY on the setpoint and supply
air temperature.
At setpoints of -9.9 C (14.1 F) and above, the
controller operates the unit on:
• Cool mode with Modulation
• Heat mode (electric heaters pulse On and Off
on a 60 second duty cycle)
• Defrost mode (electric heaters On, evaporator
fans Off)
• Evaporator fans operate on high speed (except
when Economy mode is ON and temperature
is In-range) and continuously circulate air
inside the container (except during defrost)
• Controller LED display shows the supply air
sensor temperature.
• Controller LCD display shows the setpoint
temperature.
• Controller cycles a single-speed condenser fan
ON for 2 to 30 seconds every 30 seconds
when the Condenser Fan switch is in the FAN
AIR position. The amount of ON time
depends on the condenser coil, ambient and
compressor discharge temperatures.
• Power limit is active when the unit is
operating in the Cool mode.
NOTE: When the Condenser Fan switch is
in the WATER position, the condenser fan
does not operate.
Cool with Modulation
• Controller calls for the Cool mode whenever
the Control Temperature Differential (based
on supply air temperature) is above setpoint.
• Controller turns ON the Compressor LED
when the compressor is operating.
• Controller opens and closes KVQ valve to
regulate the flow of refrigerant to the
compressor. The position of the valve
balances the unit cooling capacity against the
actual load requirements.
• Controller turns ON the In-range LED when
the supply air sensor temperature is within 1.5
C (2.7 F) of setpoint.