GENERAL MOTOR DIESEL LOCOMOTIVE. Manual - part 17

IRCAMTECH/2006/M/D/GM loco/1.0

Introduction hand book on GM locomotive February 2006

in reduction of weight. In braking mode, the three-phase
motors act as generators and power is fed back to the DC link
via the two inverters.

Traction Motor Blower

The Traction Motor Blower is mounted on the auxiliary

generator, supplies air for traction motor cooling, generator pit
aspirator operation, main electrical cabinet pressurisation and
traction computer cooling. Air is drawn through a movable inlet
guide vane through the blower, and delivered into a duct to the
traction motors. A portion of this air is diverted through a set of
filters for delivery to the computer module portion of traction
inverter cabinets for module cooling. Another set of filters
cleans the air used to pressurise the main electrical cabinet.

TCC1 and TCC2 Inverters

The locomotive has two inverters TCC1 and TCC2.

The output converter, a pulse width modulated (PWM)
inverter, is responsible for providing the variable frequency
and the variable terminal voltage for the three-phase motor.
The main alternator feeds electrical power to the DC link via
two series connected diode rectifiers. Two identical PWM
inverters TCC1 and TCC2 with GTO and their capacitors are
connected electrically to the DC link via isolating switches.
There is one traction inverter for each parallel set of three
traction motors, which are responsible for supplying power to
them. A protective circuit based on GTO is connected to the
DC link to protect the inverters against any over-voltages. The
TCC blower defuses heat produced by losses generated in
TCC.

TCC Blower

An electronic blower in each TCC cabinet driven by its

own 3-phase AC motor draws the air from central air
compartment in across the modules and expels it across the
R2 snubber resistor. This air is used for cooling and
pressurising in some parts of the inverter cabinet. This air
keeps dirt from contaminating areas containing DC link

IRCAMTECH/2006/M/D/GM loco/1.0

Introduction hand book on GM locomotive February 2006

capacitors, gate units and traction computers. The TCC blower
motor is a dual speed 3-phase AC induction motor. It operates
as a series-Y wound machine for lower speed (only low speed
configuration is used on WDG4 locomotives). Power for the
motors is taken from the companion alternator through the
main contacts of TCC1SS and TCC2SS. EM2000 exercises
control of the blower contactors at the request of the TCC via
RS-485 serial link.

Radiator Cooling Fan Motors

Radiator Cooling Fan Motors are of the inverted

squirrel cage induction type and are integral part of the cooling
fan assembly. Each cooling fan (total two per locomotive) is
driven by a two-speed AC motor, which in turn is powered by
the companion alternator. Cooling fans are powered through
contactors, which are controlled by the EM2000 program.
Each fan motor circuit consists of one slow-speed and two
fast-speed contactors that are located in the AC cabinet.

Computer EM 2000

The WDG4 locomotive is equipped with a

microprocessor based computer control system. It provides
fault detection of components and systems, it contains 'self
tests' to aid in trouble shooting locomotive faults. It has basic
features like, significant reduction in number of control
modules, better fault detection of components, memory
archive and data snap shot. The microprocessor EM2000 is
the locomotive control computer. EM 2000 utilises "Flash
PROM" memory. It is a 32 bit computer based on Motorola
68020 microprocessor running at 16 MHz with a math co-
processor communication through RS-232 serial cable / port.
EM 2000 controls the main locomotive functions based on
inputs from two traction computers. This system is equipped
with a diagnostic display system in the cab to provide an
interface between the maintenance personnel and the
computer. The computer is programmed to monitor and control
locomotive traction power, record and indicate faults that have
been incorporated into EM 2000 system.

IRCAMTECH/2006/M/D/GM loco/1.0

Introduction hand book on GM locomotive February 2006

Computer Control Brake

The locomotive is equipped with KNORR/NYAB CCB

(computer controlled braking) 1.5 system. This system is an
electro-pneumatic microprocessor based system with 30A
CDW type desktop controls. The overall purpose of using a
computer (microprocessor) to control the air brake system is to
eliminate as many of the electrical and mechanical devices as
possible, there by reducing periodic maintenance, simplifying
trouble shooting, fault diagnostics etc. It allows greater
reliability and flexibility for future system upgrade.

Dynamic Brake

Each unit of the Dynamic Brake Grid Blower Assembly

consists of fan assembly powered by a 36 HP series wound
DC motor. During dynamic braking, a portion of the current
(rectified DC) from the traction motors is shunted around one
of the resistor grids and used to power the grid blower motor.
Air driven by the grid blower drives grid heat to atmosphere.

Traction Control Computers

There are two SIBAS 16 traction control computers.

Each computer is dedicated to one inverter. SIBAS 16 is a 16-
bit computer based on an INTEL 8086 microprocessor running
at 5.6 MHz. The TCC receives data via RS-485 serial link from
the locomotive computer EM2000. The bi-directional bus
carries data such as how much power for traction the TCC
must develop as well as other information to control activation
of devices like blowers and heaters. In addition to the RS-485
data, information constantly gets fed back into the TCC, to
monitor various things such as status of relays and
temperature of various components, voltages and currents.
Based on this feed back data and information received via RS-
485 serial link, the programs stored in the TCC work to drive
the TCC as well as to protect it in the event of faulty operating
conditions.

IRCAMTECH/2006/M/D/GM loco/1.0

Introduction hand book on GM locomotive February 2006

Radar

The locomotive is equipped with a K- BAND RADAR

module. The mounting location of radar under the cab of the
locomotive near the end plate. This particular type of RADAR
system mounts at an angle of 37.5° with respect to the rail. It is
particularly susceptible to signal error as a result of inaccurate
mounting.

Under Truck

The WDG4 locomotive is equipped with a high

adhesion HTSC (High Tensile Steel Cast) truck or bogie. The
bogie assembly supports the weight of the locomotive and
provides the means for transmission of power to the rails. The
HTSC bogie is designed as a powered 'bolsterless unit'.
Although the bogie or truck frame itself is rigid, the design
allows the end axles to move or "yaw" within the frame. This
movement will allow the wheels to position themselves tangent
to the rails on curves for reduced wheel and rail wear. Axles 1
and 3 can move or kink a little bit to negotiate a curve from 0-8
degree deflection, increases the tractive effort and improves
the rolling resistance.

Traction loads are transmitted from the truck or bogie

to the locomotive under frame through the carbody pivot pin
assembly. Each bogie is equipped with three unidirectional AC
traction motors for better adhesion characteristics. The motors
are geared to the driving axles, which in turn apply rotational
force to the rails through the wheels. The driving force is
transmitted to the bogie through tractive rod attached to the
journal-bearing adapter in the frame. From the truck / bogie
frame the driving force is transmitted to the locomotive
carbody through the carbody pivot pin.

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