Efficient protection with current limiting devices

Protection from over voltage is needed in electricity distribution networks to prevent malfunction caused by for instance lightning strokes and switching actions. Current limiting devices are the most effective way to protect the network components from induced lightning surge voltages in overhead lines.

Improved power quality

Ensto’s current limiting device series SDI48 and SDI46 help in improving power quality as they protect the network from surge voltages. In the devices, the arrester is separated from the line by a spark gap and in case the arrester fails, it doesn't cause a permanent earth fault, which would mean a power outage to the customers. If the surge voltage is high enough for the spark gap to spark over, it gets conducted to the ground safely while the distribution of energy continues undisturbed. The operation of the protection device does not cause any interruptions or voltage sags to adjacent feeders.

Medium voltage surge protection

The SDI48 and SDI46 series’ devices are suitable for medium voltage overhead lines and can be used with line-post or tension insulators. The product set includes a surge arrester, a fixing bracket, an insulation piercing connector, a spark horn, or an arc protection horn. The SDI46 series devices contain a tension insulator and a shunt conductor, too. Three devices are needed for one crossarm and the installation direction is not dependent on the direction of the power feed. The arcing horn in the insulation piercing connector serves also as a personal grounding point. The horns have been tested with a fault current of 10 kA / 1 second according to EN 50397-2 standard.

Low wildfire ignition risk

Tests carried out in the Spanish laboratory LCOE prove that the current limiting device has a low wildfire ignition risk. In the test, operating voltage was applied on the device and an impulse voltage was applied on the energized setup. The operation of the device did not ignite the flammable material that was set directly below the spark gap. These test results show that the current limiting device is a perfect protection solution for dry areas. It's worth noting that the conventional surge arrester still has its place in the network protection. Please turn to Ensto to discuss the best solution for your needs.

Versatile and efficient protection with current limiting devices:

• Protecting the network components without power outages
• Uninterrupted supply of electricity to the end users
• Does not pose a wildfire risk in dry areas.