Abnormal Conditions/Overriding Functions; Fast Start; Engine Shutdown/Engine Not Running; Limp Home Mode - Komatsu 930E-2 Shop Manual

ABNORMAL CONDITIONS/OVERRIDING
FUNCTIONS
Software functions given up to this point assumed for
the most part that the truck is operating under more or
less normal circumstances. The following paragraphs
define system operation under abnormal or excep-
tional circumstances. In the event of conflict between
these functions and those given for normal operation,
the functions in this section will take precedence.

Fast Start

A fast start software function is provided to address the
case where the PSC is reset unexpectedly (power
supply glitch, etc.) while the system is running. Its
purpose will be to regain control of the truck as quickly
as possible.

Engine Shutdown/Engine Not Running

The engine must be running to enable the gate drives
and to maintain power on the DC link. Typically, the
PSC will be given advanced warning that the engine
is about to be shut off. However, if the engine stalls or
stops because of a mechanical malfunction, the sys-
tem will most likely have no advance warning. The
system reaction to an engine not running condition will
be the same as to an event carrying a "no power"
restriction except that no event will be recorded, and
no external reset to clear the condition will be required
(the no power restriction will be automatically lifted as
soon as the engine starts running). If the system is
given warning of an impending engine shutdown, the
existing torque commands will be command to zero
over a "long" ramp time (2 to 10 seconds). If no warning
is given and the engine stops running, the existing
torque commands will be command to zero over a
"short" ramp time (0.1 to 0.5 second).

Limp Home Mode

The purpose of Limp Home mode is to address the
situation where the truck has suffered a failure and is
not able to continue normal operation but is still capa-
ble of "limping" (getting either back to the maintenance
area or at least out of the way of other trucks). The
intent is that limp mode will be used by maintenace
personnel operating the truck at low speeds with the
truck unloaded. Maximum truck speed will be limited
to a reduced value while in limp home mode.
If the TCI requests limp home mode, the state machine
will ignore the restrictions associated with any fault for
which limp home mode is possible.
E2-40
Entering/Exiting Limp Home Mode
The PSC will enter limp home mode if all of the
following conditions are true:
NOTE: Two Inverter Cut Out Switches (I1CO and
I2CO), located in the switch panel on the side of the
Electrical Cabinet near the cab, can be used to cut out
an Inverter. In some cases, certain DC link bus
bars/cables within the Inverter also may need to be
removed. The DID will prompt maintenance personnel
if any of the above actions need to be accomplished.
The PSC will exit limp home mode if any of the follow-
ing conditions occur:
Electrical Propulsion System Components
1. The truck is not moving.
2. The TCI is requesting limp home mode.
3. The PSC is in Ready or test state and there is no
initiated testing in progress.
4. At least one inverter is functional.
5. There are no events active for which limp home
mode is not possible.
6. If there are any events active for which an inverter
must be turned off or cut out before limp home
mode is allowed, those actions have been taken
(Inverter is turned off or cut out as required).
1. The TCI stops requesting limp home mode.
2. An event occurs for which limp home mode is not
possible.
E02014 3/01