T-305E User Manual Version 3.5 | 8
3.
Working principle
3.1
Basic Operation
At its simplest level the surge generator can be considered to be a capacitor C which is
charged to a selectable voltage (via the transformer) and discharged into the cable through a
contactor S1. The value of the capacitor and the voltage can be changed to optimise the
surge to break down the fault.
The equipment has an internal safety discharge feature. When the equipment is powered
off, the selected capacitors and the cables will be connected to earth/ground through the
safety facility. This works by closing the switch S2 which allows the charge stored in the cable
capacitance and the surge generator capacitor to be safely
“dumped” through a resister. A
simplified scheme is shown in figure 3.1. The switch S1 can be controlled by a timer to give
periodic surges required for pinpointing.
Note: References to earth/earthing and ground/grounding are used throughout and are
interchangeable.
Figure 3.1 Surge Generator schematic diagram
