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Travelling wave monitors provide more accurate fault location

Travelling wave monitors will be installed on 220/110 kV substations in northern Finland this autumn. In addition to more accurate fault location, the devices reveal hidden faults that can be repaired before a real fault situation even occurs. The monitors are manufactured by Qualitrol and will be installed by Siemens.

The installation and design contract signed recently is worth about 140,000 euros.  The travelling wave monitors will be implemented by November. The acquisition includes the installation of 18 travelling wave monitors at substations in northern Finland.

The monitors will be installed to measure 220 kV and 110 kV transmission line fields. This will allow accurate fault location on 65 transmission lines. In theory, the travelling wave monitors produced by Qualitrol have an accuracy of 60 m, but in practice the devices can locate faults at an accuracy of 1-2 towers. The value of the monitors, which were acquired earlier, is about 240,000 euros.

Travelling wave monitors can also detect hidden faults in the grid. For example, a dirty insulator causes transient peaks before losing its actual insulation capacity. A travelling wave monitor can detect these peaks, and repairs can be performed before the fault situation even develops.

The target is to bring the entire 220/110 kV grid within the scope of travelling wave monitoring over the next few years. The work will begin in northern Finland because an outage in that grid causes the greatest problems for the fault location process now in use.