LSG 300

LSG 300

The Arc Stabilisation Unit LSG 300

Pulse echo is by far the simplest method of fault location, but its use is severely limited, not being suitable for flashing or high impedance faults. To overcome these limitations and still use pulse echo techniques a new method known as arc stabilisation can be used. As the name suggests the aim is to stabilise an arc at the point of fault, this arc then being seen and recorded by a suitable pulse echo set. Such an instrument capable of stabilising an arc at the point of fault is the LSG 300 available from Seba KMT. The LSG 300 is a compact, easy to use Arc Stabilisation Unit suitable for use in a modular system or a cable test van. The LSG 300 is an effective aid to prelocating the majority of cable faults, quickly and accurately and is suitable for use by operators of all experiences.

Test Method

The energy pulse of a shock discharge generator is applied to the faulty cable through the arc stabilising unit LSG 300. This pulse ignites the fault and generates a short-term arc at the fault. Simultaneously, the LSG 300 triggers the pulse echo set and takes a standard pulse reflection measurement into what is seen as a short circuit. A typical configuration is shown in figure 1. The pulse reflected back by the stabilised arc at the point of fault reaches the pulse echo set via the high voltage separating filter “F” and is stored in the internal memory. This trace is then compared with a previously recorded trace of the same core, the fault position is clearly identifiable as the point of divergence between the two traces. This is shown in figure 2. All switching elements necessary for the triggering and the coupling of the pulse, are contained in the LSG 300. After the pre-location using the arc reflection method, the decoupling element is bypassed using a manual switch and the shock discharge generator is ready for use on its own for acoustic pin-point fault location.