Models 5E, 5F, 5G & 5H Electric Switch Machines: Single ... - Alstom

Scheduled Maintenance4.9.9. Shunt Contact Check And Adjustment4.9.9.1. Models 5E and 5F Shunt Contacts C6, C7, D2 and D3The switch machine shipped from Alstom has shunt strips A, Figure 4–3 connectedacross contacts C6-D3 and C7-D2. Shunt strips A are used only in a polarized repeaterrelay circuit. To use a neutral repeater relay circuit, shunt strip A must be removed andshunt strip B must be added between contacts C6-C7 and D2-D3, Figure 4–4 Shuntstrips B, supplied with each new machine, are in a bag which also contains the motorventilators.When the switch machine operates, the first or unlocking movement of the locking barsimultaneously opens the snub contacts and either the normal or reverse contacts,depending on the direction of operation.Immediately after these contacts are opened, the shunt contacts are closed. With themachine unlocked, or if the point-detector rod is out of adjustment, there is a shunt onthe repeater relay circuit. The shunt prevents pickup of the repeater relays so that anyextraneous energy, which may be present, cannot cause a false indication.In a polarized repeater relay circuit using shunt strips A, Figure 4–3 the shunt is closedthrough terminal post C6, U-shaped spring (1), front stop (2), shunt strip (A), front stop(3), U-shaped spring (4), and opposite terminal post D3. A similar shunt arrangementexists between posts C7 and D2.Figure 4-3. Shunt Contacts Used in Polarized Repeater Relay CircuitIn a neutral repeater relay circuit using shunt strips B, Figure 4–4 the shunt is closedthrough terminal post C6, U-shaped spring (1), front stop (2), shunt strip (B), front stop(3), U-shaped spring (4), and adjacent terminal post C7. A similar shunt arrangementexists between posts D2 and D3.P1293, Rev. Jun/07 4–32 Alstom Signaling Inc.