iVPI Subrack - Alstom

System Subrack1.7. POWER ISOLATION UNITThe 12VDC (nominal) power to the backplane is supplied through a separate PowerIsolation Unit (31166-447-01) that is mounted to the rear side of the backplane via sixpower-tap high current screw connectors. The Power Isolation Unit provides the safetyisolation between the battery voltage and the Motherboard. This eliminates the need foran external DC/DC Converter.External power is brought into the Power Isolation Unit via terminal block TB1. Terminalblocks TB4 and TB5 provide local distribution of the input voltage for accessories suchas a local control panel. Remote supply enable of the Power Converter Module isprovided through TB2 and TB3. Connecting these two terminals together (through atoggle switch) enables the supply and generates the isolated output voltage. Isolated12VDC is provided for external use through TB6 & TB7.Connections TB2, TB3, TB4, TB5, TB6 and TB7 incorporate levers for wire installationand removal. No special tools are required. Connection TB1 requires the use of a smallflat blade screwdriver, which is inserted into the top, rectangular opening. The wire isinserted into the lower round opening. Press the screwdriver into the rectangularopening at a slight downward angle to insert/release the wire.Table 1–2. Power Isolation Unit ConnectionsFunctionConnectionsInput Power:Output Enable:TB1: 12VDC (nominal) Input Power, Spring Clamp TerminalBlock 24 - 6 AWGTB1-1: 12VCOMTB1-2: 12VDCTB4 and TB5: 2-Position Spring Clamp Block 28 - 12 AWGTB4: DC IN – (connected to TB1-1)TB5: DC IN + (connected to TB1-2)TB2 and TB3: 2-Position Spring Clamp Block 28 - 12 AWG12 V Output: TB6 and TB7: 2-Position Spring Clamp Block 28 - 12 AWGTB6: 12VCOM (isolated)TB7: 12VDC (isolated)P2521B, Volume 2, Rev. 2, Feb/11 1–8 Alstom Signaling Inc.