Choisissez votre région et votre langue


Spark Prevention Unit

Reducing wildfire hazards which may be caused by thermally overloaded surge arresters

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.

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.


  • For use with Hitachi Energy surge arresters in medium-voltage distribution networks
  • Especially made for areas with risk of wildfires

Why Hitachi Energy?

  • Over 100 years of experience in overvoltage protection
  • Unique and patented design
  • Inhouse production of metal-oxide (MO) resistors
  • Approved for vegetation clearance exemption according to CalFire regulation
  • Easy to install
  • Local and global Hitachi Energy application support

Brief performance data

Nominal Discharge Current In 10 KApeak
High Current Impulse Ihc (4 / 10 μs) 100 kApeak
Service conditions:  
Ambient air temperature Tamb −40 to +55 °C
Altitude up to 1800 m (for higher altitudes contact Hitachi Energy)
Frequency of system voltage 40 to 62 Hz