VRIOGS 010.7 RevA - Public Transport Victoria

26 VRIOGS 010.7 Revision A6.9.5 Side Leads1. There shall be a minimum of two side leads from the impedance bond to eachrail. The track bonding plans specify the number of side leads required inparticular situations.2. Side lead connections to rail shall be made as close as practical to theinsulated joint. Where the insulated joint has been ‘Thermit’ welded in place,the side leads shall be connected between the joint and the weld.3. Impedance bond cables are to be identified at the point of rail connection andon the impedance bond connection; in accordance with this specification.4. To minimise traction return system resistance, all side leads should be keptas short as possible, while maintaining a tidy and safe installation.5. To avoid unreliable operation of the impedance bond due to traction currentimbalance, all side leads on any individual impedance bond shall be of equalDC resistance. Generally, making all leads of equal length will satisfy thisrequirement. Where impedance bonds are mounted off track, the upper orfarther side lead shall be connected to the near rail and the lower or nearerside lead shall be connected to the far rail. To facilitate the use of equal sidelead lengths, side lead rail connections shall be to the inside face of each railand the upper side leads on vertical frame-mounted impedance bonds shouldbe terminated to the bond from above. Where welded head-bond connectionsare used, these shall be connected to the outside of the rail.6.9.6 Neutral Point1. The neutral connections between adjacent impedance bonds shall preferablyconsist of a tinned copper busbar as specified in this specification. Thisbusbar should also be used for terminating any cables for tie-in bonds orconnections to substation or sectioning hut busbars.2. Where the copper bus connection is not practical, such as with mid trackmounted impedance bonds, there shall be a minimum of four neutral leadsbetween the impedance bonds.3. Cables between impedance bond neutral points shall be kept as short andstraight as possible.4. Where the impedance bond is used to change from a single rail to a double railtrack circuit, the total number of neutral leads specified shall be connected tothe common (traction) rail of the single rail track circuit.NOTE: This document is controlled only when viewed on the DOT Engineering Standards website.Any other copy of this document is uncontrolled, and the content may not be current.