Special Precautions For Working On Ac Drive Trucks; Preliminary Procedures Before Welding Or Performing Maintenance; Engine Shutdown Procedure Before Welding Or Performing Maintenance - Komatsu 930E-4SE Operation & Maintenance Manual

OM2042 7/11

SPECIAL PRECAUTIONS FOR WORKING ON AC DRIVE TRUCKS

PRELIMINARY PROCEDURES BEFORE
WELDING OR PERFORMING
MAINTENANCE
Before welding or repairing an AC drive truck,
maintenance personnel should notify a Komatsu
service representative. Only qualified personnel,
specifically trained for servicing the AC drive system,
should perform this service.
If it is necessary to perform welding or repair to the
truck without the field engineer present, the following
procedures must be followed to ensure that the truck
is safe for maintenance personnel to work on and to
reduce the chance for damage to equipment.
Anytime the engine is running, do not open any
of the cabinet doors or remove any covers. Do
not use any of the power cables for hand holds or
foot steps. Do not touch the retarding grid
elements.
Before opening any cabinets or touching a
retarding grid element or a power cable, the
engine must be shutdown and the red drive
system warning lights must not be illuminated.
ENGINE SHUTDOWN PROCEDURE
BEFORE WELDING OR PERFORMING
MAINTENANCE
Normal operation of the AC drive system at shutdown
should leave the system safe to service. However, in
the event of a system failure, performing the following
procedure before any maintenance activities will
ensure that no hazardous voltages are present in the
AC drive system.
1. Before shutting down the engine, verify the
status of all the drive system warning lights on
the overhead display panel. Use the lamp test
switch to verify that all lamps are functioning
properly.
If any of the red drive system warning lights
remain on, do not attempt to open any cabinets,
disconnect any cables, or reach inside the
retarding grid cabinet without a trained drive
system technician present, even if the engine is
off. Only qualified personnel, specifically trained
for servicing the AC drive system, should
perform this service.
2. If all red drive system warning lights are off,
follow the Normal Engine Shutdown Procedure
in Section 30, Operating Instructions.
3. After the engine has been stopped for at least
five minutes, inspect the link voltage lights on
the exterior of the main control cabinet and
back wall of the operator's cab (DID panel). If all
lights are off, it is safe to work on the retarding
grids, wheel motors, alternator and related
power cables.
4. Locate the GF cut-out switch in the access
panel on the left side of the main control
cabinet. Place the switch in the "alternator
cutout" position. This will prevent the alternator
from re-energizing and creating system voltage
until the switch is returned to its former position.
Safety - Section 20
Page 20-15