The D3/LLI Live Line Indicator is for providing temporary earth bonds between overhead catenary or contact conductors and earthed rail sections or recognised earthing points.
The D3/LLI Live Line Indicator is a resistive type voltage detector designed for use on overhead a.c. rail electrification systems operating at 25kV nominal voltage. The ‘LLI’ threshold is specified as 12kV ± 5%, however it should be noted that induced voltages could reach 10kV.
The unit is designed to be mounted on approved fibreglass earth poles with the pole immediately below the indicator being the primary insulator (ref 91-2410). The signal emitted by the D3/LLI is both audible and visible. Power is provided by a rechargeable battery, housed within the main unit. The battery can be charged in situ using the charger supplied.
The unit comprises a main unit and a contact probe. The contact probe is manufactured from lightweight fibreglass tubing and houses the calibrated resistor stack. The pole section is foam-filled to increase its voltage withstand. The probe is connected to the overhead line by a replaceable Aluminum hook. The top of the pole is coated in a special high reflectivity paint to ease visibility when applying the indicator in poor lighting conditions.