Komatsu 830E Shop Manual page 158

System Operation
When the operator depresses the accelerator foot
pedal to propel the truck, two signals are generated.
One signal is generated by a potentiometer on the foot
pedal and is sent to the engine control system to regu-
late engine speed. The other signal is generated by
closing a switch* and is sent to the digital input/output
card to set up propulsion circuits for power.
*NOTE: On trucks equipped with the "Fuel Saver"
system, the foot pedal potentiometer signal is sent
directly to the FL275 panel and the switch signal is not
required.
A speed sensor signal from the engine is sent to the
analog input and output card to establish the accelera-
tion (power) reference signal used by the propulsion
control system to establish horsepower demand.
NOTE: The analog input and output card in the FL275
panel responds to both accelerator and retard foot
pedal signals. Both signals are processed through the
central processing unit CPU, returned to the analog
card where another signal is generated and fed to the
FM466 and FM467 Static Exciter panels.
The output signal from the analog card is a burst of fir-
ing pulses. This AC signal is constant in frequency and
amplitude, and is of both negative and positive polari-
ties. Synchronizing AC signals from the tertiary wind-
ings of the Alternator provide timing to synchronize the
firing pulses to the AC power frequency from the Alter-
nator.
NOTE: Firing pulses are generated according to the
demand from the operator (accelerate or retard) and
biased by feedback signals from the power circuit.
They are used to fire Silicon Control Rectifiers (SCRs)
in two, single-phase, full-wave rectifier bridges, one
each in FM466 and FM467 rectifier panels, and
thereby regulate output current from these panels.
The output current from the FM466 AFSE (Alternator
Field Static Exciter) panel energizes the field coils of
the Alternator. The level of current in this field coil
determines Alternator output.
The output current from the FM467 MFSE (Motor Field
Static Exciter) panel energizes the field coils of the
Motorized Wheels. The level of current in these field
coils determine motor horsepower output.
The main output voltage from the Alternator, generated
by the rotation of the Alternator rotor and regulated by
its exciter field coil, is 3-phase high voltage AC. This
AC power is fed to a rectifier panel to convert AC to DC
for use in the Motorized Wheel armatures.
E2-2
The output of the FM528 rectifier panel is variable high
voltage DC current, used to power the Motorized
Wheels. A full wave bridge in the panel rectifies the 3-
phase input voltage from the Alternator to DC.
In parallel with the Motorized Wheels, high voltage DC
is also fed to the VMM1 panel, to be used for feedback
to the control system.
High voltage from the power circuit is attenuated by the
VMM1 panel to a level acceptable to the electronics on
the analog input/output card. From there it is processed
through the CPU card to bias power and retard
demand signals in the analog card.
Speed Sensor signals from both Motorized Wheels are
sent to the control system analog input and output card
to operate various speed event functions.
The CPU card uses speed sensor signals to develop
various levels of output voltages for use in generating
the speed taper function in retarding and for (option-
ally) driving the speedometer and tachometer.
NOTE: Speed taper is used to reduce maximum
dynamic retarding effort at high truck speeds. This is to
protect the Motorized Wheel motors from excessive
current and possible damage.
When the operator depresses the retard foot pedal to
slow the truck, a signal is generated by a potentiometer
on the foot pedal and sent to the control system to
establish the retarding circuits and the desired retard-
ing effort.
A wheel slide compensation option, "Wet Weather
Retard Speed Control", can be enabled which will mod-
ify the method of retarder application on slippery roads.
This software settable option reduces wheel slide dur-
ing operation on wet or icy roads by automatically
reducing the retarding effort (requested by the opera-
tor) to a slipping wheel if the system senses a slide is
occurring. When the system determines the slipping
wheel has regained traction (the wheel speed
increases to approximate the speed of the non-slipping
wheel), retarding effort is restored based on the
amount of retarding effort requested by the operator.
Electrical Propulsion Components 2/02 E02016