Thermo King SB-210, Manual

Page: 29 / 159

Unit Description
29
Unit Protection Devices
Coolant Level Switch:
The coolant level switch
closes if the coolant level drops below an
acceptable level. If it stays closed for a specified
time, the microprocessor records alarm code 37.
Engine Coolant Temperature Sensor:
The
microprocessor uses the engine coolant
temperature sensor to monitor the engine coolant
temperature. If the engine coolant temperature
rises above an acceptable level, the
microprocessor records alarm code 41 and
possibly 18. The the microprocessor might also
shut the unit down.
Fuse Link (Current Limiter):
The fuse link is
located in the positive battery cable. The fuse link
protects the electric system from a short.
Fuses:
Various fuses are located on the controller
interface board to protect circuits and
components. See “Fuses” on page 71 for more
information.
High Pressure Cutout Switch:
The high pressure
cutout switch is located on the compressor
discharge manifold. If the compressor discharge
pressure becomes excessive, the switch opens the
circuit to the fuel solenoid to stop the engine.
High Pressure Relief Valve:
This valve is designed
to relieve excessive pressure in the refrigeration
system.
Low Oil Level Switch:
The low oil level switch
closes if the oil drops below an acceptable level. If
it stays closed for a specified time, the
microprocessor shuts the unit down and records
alarm code 66.
Low Oil Pressure Switch:
The low oil pressure
switch closes if the oil pressure drops below an
acceptable level. If it stays closed for a specified
time, the microprocessor shuts the unit down and
records alarm code 19.
Preheat Buzzer:
The preheat buzzer sounds when
the controller energizes the preheat relay. This
warns anyone near the unit that the controller is
about to start the engine.
Overload Relay—Manual Reset (Model 50):
An
overload relay protects the standby electric motor.
The overload relay opens the circuit to the electric
motor if the motor overloads for any reason (e.g.,
low line voltage or improper power supply) while
the unit is on electric standby operation.