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µP-T System Description
General Description
The µP-T microprocessor controllers are self
contained temperature control units designed for
Smart Reefer (SR) truck units.
The Model 50 unit is powered by either a diesel
engine or an external electric standby power
source turning an induction motor. The unit
mounts on the upper front of the truck box and the
evaporator extends into the box. The compressor,
condenser and evaporator fans are driven by belts.
Defrost is accomplished by means of hot gas
when operating in Diesel mode and hot gas and
electric evaporator heaters (option) when
operating in optional Electric Heat mode.
µP-T Control System
The µP-T microprocessor control system consists
of the following main components:
• Microprocessor Power Switch
• Remote Control Panel
• µP-T Microprocessor
• Interface Board
•Sensors
• Refrigeration System Controls
• Engine Controls
• High Voltage Tray (Model 50 Units).
Microprocessor Power Switch
The Microprocessor Power switch applies 12 Vdc
control power to the microprocessor and must be
On to operate the unit. It is located on the unit
frame just below the control box on the side of the
unit. Main power to the balance of the controls is
supplied by the 50 amp circuit breaker CB1.
NOTE: When the Microprocessor Power Switch
is turned to the Off position, power is still applied
to the Interface Board and control circuits via
CB1. To completely remove power from the
control system, disconnect the unit battery.
Figure 11: Microprocessor Power Switch
For additional information, see µP-T
Microprocessor Diagnosis Manual.
Optional Electric Standby
(Model 50 Units Only)
The Electric Standby option allows the unit to be
operated on either the diesel engine or external
electric power. The units can be supplied to
operate on either single phase or three phase
power.
CAUTION: Dangerous single phase or
three phase AC power is present whenever
the unit is operating in Electric mode or
whenever the unit is connected to external
standby power. Voltages of this magnitude
can be lethal. Exercise extreme caution
when working on the unit.
CAUTION: High voltage AC power is
present whenever the unit is operating in
Electric mode and whenever the unit is
connected to external standby power.
Voltages of this magnitude can be lethal.
Exercise extreme caution when working
on the unit.
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