STC SmartScanIS, Руководство пользователя

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14 January 2021, SmartScanIS User’s Guide for Union Pacific, EUD-2016026-00 Rev.2
Each HP9-915 antenna is installed:

Vertically with its face parallel to the rails

10 feet (3 meters) from the center of the track

3.5 feet (1.1 meters) above the top of the rails

Centered between the transducers

Opposite each other
2.5 Track Circuit
Some SmartScanIS sites use a track circuit to detect train presence. Other sites use advance
transducers for this purpose.
The track circuit is nothing more than two wires attached to the rails. One wire is attached to
each rail. They are attached directly opposite each other, centered between the gating
transducers. Connection to the rail can be made in one of two ways.

Bonding – Cadweld manufactures a line of bond welding systems that are commonly
used in the rail industry. The recommended practice is to weld a short length of bond
strand to the web of each rail. Cadweld can provide these items as prepackaged kits,
which include the bond strand (a 3/16-inch (4.8-millimeter) diameter strand is
recommended), and the one-shot welding system. A reusable mold of the correct size
is required.

Drilling – The alternative to Cad-welding is to drill a 3/8-inch (9.5-millimeter) hole in
the web of each rail at the neutral axis, and apply a bonding kit. The kit includes
ready-made lengths of bond strand with "chicken heads" attached. The "chicken
heads" are tapered solid metal inserts that can be driven into the 3/8-inch
(9.5-millimeter) holes to establish a permanent connection to the rail.
Once the rail attachment is made, extend the connection to the Surge Protection Subassembly
in the SmartScanIS enclosure. You do this by splicing a length of wire to each bond strand.
Okonite Cable makes a twisted-pair cable (Okonite 113-12-3933) that is suitable for direct
burial. The cable has two 6 AWG solid conductors and a very rugged insulation jacket. The
cable should be attached to the bond strand using compression sleeves.
The track circuit is used in conjunction with the 2200-500 Presence Detector, which is
described in
Chapter 4 - Bungalow Components . This module continuously sends a signal
down one of the wires of the track circuit. When the wheels-axle of a train (or any metal
object) shunts the track, this completes the circuit, causing the signal to return to the 2200-500
Presence Detector via the other wire. At a certain distance from the track circuit, the
amplitude of the signal is strong enough to trigger an active high, which indicates to the
SmartScanIS that a train is present. This shunting zone is adjustable up to 150 feet
(45.7 meters) on each side of the attached track-circuit wires.