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Vital Subsystem
5.3
VRD (VITAL RELAY DRIVER) BOARD P/N 59473-740
This board plays a key role in assuring the vitality of the system. It produces an output
voltage that operates a 100-ohm Alstom Type B1 relay (56001-787-05) if, and only if,
the data sent to it by the main processing system is exactly correct. If any of these
checkwords are not precisely correct, the VRD output is shut off and the external relay
de-energizes. The field energy that is delivered to the Vital output boards is broken
through front contacts of this Vital relay or a repeater of it. Thus, power will be removed
from the outputs when the Vital checkwords are incorrect.
5.3.1
VRD Relay
USE ONLY ALSTOM VITAL RELAY WITH VRD BOARD
Only Alstom VRD relay (P/N 56001-787-05) is to be used with the Alstom
VPI system VRD circuit board. Alstom products are designed to function
within all-Alstom systems. The introduction of non-Alstom products into an
Alstom VPI system could have unintended and unforeseeable safety
consequences.
Failure to comply can degrade the safety performance of the train control
system resulting in property damage, injury, and/or death due to train
collision or derailment.
P2086G, Rev. E, Jan/15
5-4
Alstom Signaling Inc.