Thermo King SR-2 SmartReefer2, Diagnostic Manual

Page: 45 / 431

Section 2 – SR-2 Hardware Description
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 are supplied to operate on
three phase power.
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.
Model 50 Features
The following features are standard equipment on
units equipped with Electric Standby.
•
Automatic Diesel/Electric Selection – The unit
can be programmed to automatically switch to
electric operation when a power cord is
connected and the standby power is switched
“on”. The unit can also be programmed to
automatically switch back to diesel power if the
standby power is switched off or fails. The HMI
control panel will prompt for electric or diesel
switchover if the respective autoswitch feature is
not enabled.
Note: The unit will automatically switch to Cycle
Sentry when the unit is manually switched or
autoswitched to electric mode.
•
Automatic Overload Reset - The overload
relay resets automatically after the motor cools.
When the overload trips, it interrupts power to
the motor contactor coil.
•
Electric Heat – Both hot gas and electric heat is
utilized on model 50 units. The electric heaters
are also used during defrost.
•
Automatic Phase Correction - The control
system features two motor contactors. One of
the connectors is energized by the phase
detection module to insure correct motor
rotation, regardless of phase rotation on the
incoming power. The motor contactors are also
mechanically interlocked.
•
Low Voltage Detection – The phase detection
modulation will not allow the unit to run if the
supply voltage is too low.
•
Single Phase Protection – The phase
detection modulation will not allow the unit to run
if it detects a single phase condition.
2-29
31 January 2005