Section 2 – SR-2 Hardware Description
High Voltage Components
The high voltage enclosure or tray contains the
motor contactors, overload relay, heater contactor
and phase select module used to operate the drive
motor on units equipped with Electric Standby. The
contactors are controlled by +12 volt dc control
signals from the interface board. SB units have a
separate control box located on the compressor side
of the unit for these high voltage components. SL
units utilize a high voltage tray located inside the unit
control box.
Diesel/Electric Relay K5
The Diesel/Electric Relay K5 is present on all units.
If the Electric Standby option is not present or if the
unit is running in Diesel Mode then control power is
routed through the Diesel/Electric Relay normally
closed contacts.
The Diesel/Electric Relay is energized and LED 7 is
lit when the microprocessor requests Electric Mode
operation. The K5 Diesel/Electric Relay normally
open contacts supply power to the 7E circuit to
enable Electric Mode operation.
Heater Contactor HC
The heater contactor is used to supply standby
power to the electric heaters during heat and defrost
mode electric operation. The heater contactor is
energized and LED 5 is lit when the microprocessor
energizes the K3 High Speed Relay during electric
mode operation. The K3 High Speed Relay Smart
FET supplies chassis ground via the 26E wire to the
heater contactor. The circuit is protected by the
Smart FET.
Phase Detect Module
The phase detect module is designed to monitor 3
phase voltages from 160 volts AC through 510 volts
AC. The phase detect module detects missing
phases, automatically corrects phase rotation, and
provides low voltage protection. See Section 6 for
operation and diagnostics.
THERMO KING
9131C98G06
L1
L2
L3
0202
Brown
Blue
Black
Phase Detect Module
2-30
31 January 2005
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