Partial Cable Severing

TM-11-5830-263-20&P

c. Partial Cable Severing

If any cable is partially severed, the system will continue to operate without any performance

degradation.

If either or both conditioned power conductors are severed, power is still available at each

unit. With both data-bus conductors still intact, the ARC will not close.

If either or both ground conductors are severed, ground returns are still available because of

the ring architecture. Again, with both data conductors still intact, the ARC will not be

triggered.

If either or both data bus conductors are severed, the ARC will trigger, reconnecting any

unconnected units instantly.

If the ground shields are totally severed, the ground is carried around the ring in both

directions by the cable and also through the vehicle body to each FFCS, MOS, and RIT. The

loss of shielding is not significant and will not affect the operation of the system.

d. Partial Cable Severing with Shorted Conductors

If a cable is partially severed and the conductors are shorted together, the system cannot

continue to operate normally. None of the units will be damaged internally, no matter which

leads are shorted.

Either data bus conductor may be shorted to either of the power conductors, either of the

grounds, or the zero volts ground shield without affecting the VIS operation. The transformer

coupling of the data bus to each unit prevents damage.

If the data bus conductors are shorted together, or both to ground, or both to the same

conditioned power conductors, the data bus cannot function. All communications will cease

and the CPM software will cause the MCS to display in sequence that all units in the system

have become unconnected (e.g., 1 u, 2u, 3u, 4u, Au, Bu.... ru), showing that the whole data

bus has been stopped. As soon as the damaged cable is disconnected, all communications

are restored.

If the +28Vdc conditioned system power conductor is shorted to the zero volts ground, the

MCS system power conditioning circuit overcurrent limit will trip at approximately two amps.

The system is then effectively isolated from power and only a single LED on the MCS display

will be illuminated. This would indicate that the overcurrent limit circuit has tripped. In this way

the system isolates itself from further damage. The ANR power supply will remain intact,

allowing ANR protection to remain operational. For immediate corrective action, the faulty

cable section will be disconnected. Following disconnect, replacement or repair of the

damaged cable, the trip circuit may be reset by switching the MCS SYSTEM switch to "off"

and then back to one of the "on" positions, restoring full system operation.

If the +24Vdc conditioned ANR power conductor is shorted to the zero volts ground, the MCS

ANR power-conditioning circuitry will operate its overcurrent limit trip circuit. This circuit is set

to trip at approximately two amps. ANR equipment will then cease to operate and the MCS

CPM will indicate that the overcurrent limiter has tripped while the VIS system will continue to

operate normally. Following replacement or repair of the damaged cable, the trip is reset by

switching the MCS SYSTEM switch to "off" and then back to one of the "on" positions.

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