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Resistor Grid Control
The first resistor grid (RG1) will always be engaged
when retard is active since the grid blower motors are
wired across it.
The second and third fixed resistor grids (controlled by
RP2 and RP3) will be engaged as needed to dissipate
the energy produced in retard state. Limitations are:
1. The use of RP2 and RP3 will be alternated to
provide even wear on the contactors.
2. The grids will be engaged to prevent drawing
more power than the motors can produce. At high
motor speeds the maximum motor torque does
not produce enough power to support three grids
across the DC link (at the given voltage). There-
fore, at high speeds, only two resistor grids will be
engaged.
Chopper Voltage Control
Chopper turn-on voltage will be set to give the motors
as much of the retard envelope as possible (i.e., keep
the voltage as close to the maximum value as possible)
and to keep the DC link voltage at or below the
maximum link voltage value.
Auxiliary Blower Control
The Auxiliary Blower Control regulates the tempera-
tures of the AFSE, auxiliary blower system, rectifier
diodes, phase modules, chopper modules, and trac-
tion motors by controlling the speed of the auxiliary
blower. Additionally, this software function checks for
faults in the auxiliary blower.
This software function is performed using the following
process:
1. The commanded auxiliary blower speed will be
calculated to control all system temperatures.
The control priorities will be:
a. Keep all temperatures below allowable maxi-
mums.
b. Keep the GTO temperatures as constant as
possible.
2. If the aux blower system status (AUXOK) indi-
cates the aux blower system is not okay, a reset
pulse will be sent. Additional reset pulses will be
sent at periodic intervals if the aux blower system
does not respond.
E2-36
EVENT PROCESSING
The PSC contains very powerful troubleshooting soft-
ware. The PSC software constantly monitors the AC
drive System for any abnormalities (events).
Automatic self-tests are performed periodically on vari-
ous parts of the system to ensure its integrity. Addition-
ally, there are some elaborate tests which may be run
by an electrician with the use of DID screens. Predic-
tive analysis is used in some areas to report potential
problems before they occur.
The troubleshooting system is composed of two parts:
Event Detection
This software function is responsible for verifying the
integrity of the PSC hardware and the systems to
which the PSC interfaces by detecting an "event"
(abnormal condition).
The events fall into three detection categories:
Power On Tests
Three power-on tests are executed once every time
power is applied to the PSC. They are as follows:
Electrical Propulsion System Components
1. The PSC for detection, event logging, data stor-
age and fault light indications.
2. The TCI (or a PTU) for retrieval of stored event
information, real time vehicle status, trou-
bleshooting, etc.
1. CPU Card Checks - Upon powerup, the PSC will
confirm the integrity of its CPU card hardware
before transferring execution control to the appli-
cation program residing in its FLASH memory.
2. Battery-backed RAM (BBRAM) Test/Adjustable
Parameter Initialization - A battery backed RAM
(BBRAM) check will be performed to check for
BBRAM data integrity. If the check fails, all
TCI/PTU-adjustable parameters will be initialized
to their default values.
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Table of Contents
Troubleshooting
