Electrical System with TX and TT Card
PS
S5.0
5000
F-code
Section
C-code
Version no
T-code
001
OE35
© BT Products
141
Service Manual
1997-10-23
4.14. Pulse Monitor Trip (PMT)
This feature contains three features which shuts down or
locks out control operation if fault conditions exist that would
allow uncontrolled (run away) speed of the vehicle:
Look ahead
Look again
Automatic look again and reset
The PMT circuit will not allow the control to start under the
following conditions:
1. If 1REC is shorted or if 1A contactor is welded, the
control will not allow the forward or rearward
contactor to close.
2. Will not allow the control to operate if forward and
rearward internal coil drivers are shorted or if 3
REC diode is shorted.
The PMT circuit will shut down operation of the control
(opening of the forward or rearward contactor) under the
following conditions:
If 1REC fails to commutate (shut off), or if 1A power tips
remain closed when they should be open. After opening the
forward or rearward contactor the PMT circuit will check for a
fault and if none is found will reclose the directional contactor.
If the fault still exists, the directional contactor will open and
remain open.
If 1A closes before a second commutation failure, the look
again counter will automatically reset. This eliminates the
inconvenience of resetting the PMT with the key switch if the
trip is due to random noise.
When the PMT circuit prevents forward or contactors from
closing, the PMT circuit can be reset only by opening the key
switch.
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