Coordinated surge protection

Coordinated surge protection according to IEC 60364 and IEC 61643

Effective surge protection in PV systems requires a coordinated SPD setup (Surge Protection Devices), based on the EMC zoning concept (LPZ 0A to LPZ 2). Each zone transition defines the maximum allowed residual voltage, which must align with the rated impulse withstand voltage (Uw) of the connected equipment, as outlined in IEC 60364-4-44, Clause 443.6.2.

 

Rated impulse withstand voltages (IEC 60664-1):

  • Category I (1.5 kV): Sensitive electronic equipment

  • Category II (2.5 kV): Standard connected devices

  • Category III (4.0 kV): Fixed installation components with higher reliability demands

coordinatie-bliksem

SPD yypes and placement

Type 1 SPD – Lightning current arrester

  • Installed at LPZ 0A → LPZ 1 boundary (e.g. main distribution board)

  • Handles 10/350 µs lightning current

  • Required when LPS (Lightning Protection System) or conductive steel structure is bonded to the earth system

  • Residual voltage < 4 kV

  • Always used in combination with Type 2 (and optionally Type 3)

 

Type 1+2 SPD – Combined protection

  • Compact device for direct-connected equipment
  • Handles both lightning (10/350 µs) and switching surges (8/20 µs)
  • Residual voltage < 1.5 kV
  • Suitable for cable lengths ≤ 5 m
  • Replaces separate Type 1 and 2 where space or simplicity is a factor

 

Type 2 SPD – Surge arrester

  • Used for overvoltage protection against field induction or switching surges
  • Installed in the main or sub-distribution board
  • Appropriate for LPZ 0B → LPZ 1 transitions
  • Protects connected end circuits or inverter input

 

Type 3 SPD – Device-level protection

  • Installed near sensitive end devices (LPZ 2)
  • Provides protection against residual surges beyond Type 2
  • Only effective when located close to the equipment

 

Installation Notes

If cables remain within the same LPZ and are shorter than 10–15 meters, an additional SPD in the next distribution board may not be required.
When no LPS is present, Type 1 SPD is generally omitted. Protection starts from Type 2.

 

Need help designing your SPD layout? Contact us at info@conduct.nl or call +31 180 531120. Our specialists will support you.