The adjustable arc suppression coil is a new product in ABB's range, and it compensates earth fault currents. The development of new products is part of the role of the Vaasa Transformers unit. Vaasa is the lead manufacturing unit for special transformers in Product Group Small Power Transformers.
EU legislation promotes the new product's markets. "EU legislation encourages electrical grid companies to improve their grids, because customers have the right to get monetary compensation for supply failures lasting several hours," says Head of Research Esa Virtanen.
Electricity grid companies want to build electrical grids that are protected against storm damage and use more underground cables instead of overhead wires. This increases earth fault currents and contact voltages caused by the currents.
Safety regulations set certain limits for contact voltages, which can be reached either with a very good and robust earthing or by using arc suppression coils, i.e. resonant earthing. Contact voltages are limited to ensure electrical safety. They are dangerous not only to people but also, for example, to domestic animals put out to pasture.
The earth fault current is compensated when the inductive component running through an arc suppression coil voids the capacitive component running to ground at the fault location. With the help of adjustable arc suppression coils, an electrical grid can easily be expanded and its loading increased without exceeding the safety limits. An adjustable arc suppression coil is connected either directly to the neutral point of the main transformer or to a separate earthing transformer. In addition, a controller and an isolating switch are needed - usually customers use ABB's Sectos switch - as well as protection.
The adjustable arc suppression coil made by ABB is designed for the underground cable networks of cities and population centers. In addition to Scandinavian electricity grids, the product is suitable for grids in continental Europe, Russia and the Baltic countries. Another kind of technology is used in England; earthing resistors are used instead of arc suppression coils.
| Technical characteristics | |
|---|---|
| Power range | 125 kVAr - 30 MVAr |
| Voltage | 6 kV - 145 kV The device can operate in two-hour phases or continuously |
| Frequency | 50 Hz (if necessary 60 Hz) Can be installed indoors or outdoors |
Benefits
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