Spark prevention unit (SPU)

Spark Prevention Unit (SPU) is designed for surge arresters that are installed in wildfire risk areas. It monitors the current and the thermal load of the surge arrester. In case of a thermal overload, it interrupts the current flow and disconnects the surge arrester thus preventing any arcing, sparking or ejection of hot particles that may have the potential to start a wildfire.

When operated, SPU gives an indication that is easily visible from the ground level, so that the arrester can be replaced upon visual indication. However, such an operation means the protective function of surge arrester cannot be performed and thus the line equipment are exposed to the risk unless the arrester and SPU are identified and replaced. To make this process of monitoring easier, SPU can also be equipped with a wireless monitoring device.

Medium-voltage surge arresters equipped with SPU from Hitachi Energy are approved for vegetation clearance exemption according to CalFire (California Regulation). They are also considered spark-free according to class A of Australian Standard AS 1307.2.