Thermo King 098916, Maintenance Manual

Page: 118 / 196

117
Electrical Maintenance
Unit Protection Devices
Introduction
The unit has numerous protection devices. They
are described in detail on the following pages.
Main Circuit Breaker
The main power circuit breaker is located in the
control box. The 25 ampere manual reset circuit
breaker is located in the Control Box. It protects
the 460/380V power supply circuit to the unit
electric motors and control system transformer.
Control System Fuse
A 7.5 ampere automotive blade type fuse protects
the 29 Vac control circuit. This fuse is located
inside the control box (right side) on the terminal
block rail.
Control Circuit Fuses
Two control circuit fuses are located on the
controller. They protect the unit circuits and
components. No fuses are present on newer
controllers.
Evaporator Overheat Switch
A temperature switch near the evaporator coil
opens to de-energize the heater contactor if the
evaporator temperature reaches 54 ± 3 C
(130 ±5 F). The switch closes (resets) when the
evaporator temperature decreases to 38 ± 4.5 C
(100 ±8 F).
Newer units do not have this overheat switch. The
coil sensor is used for overheat protection.
1. Main Circuit Breaker
Figure 61: Main Circuit Breaker
1. Control System 7.5 Amp Fuse (ATO)
Figure 62: Control System Fuse
1
AXA0342
1
AMA312
1. 28 Vac Control Circuit Fuse, 2 ampere
2. 28 Vac Control Circuit Fuse, 2 ampere
Figure 63: Control Circuit Fuses
AMA308
1
2