FTL - Functional Principle
One FTL block contains 10 modular units (or “poles”) each allocated to a current, voltage, signal or trip circuit. Each circuit is connected through the block via two silver-coated copper contacts, pressed securely together by two pressure springs to create a highly conductive electrical connection.
To open one of these modular poles, a high-quality insulation plastic pin is inserted between the copper contacts. When the pin is removed, the springs naturally force the contacts back together, returning the circuit to its normally-closed position and eliminating the risk of accidents from improperly closed circuits.
During normal closed-circuit operation, when the pin is not needed, it is stored in a parking position at the top of the block. At a glance, one can easily tell by the position of the pins whether a particular contact is open or closed.