2. Surge Phenomena & Overvoltages · Page 2 of 6
Sources of Surges in LV Networks
Lightning, switching, faults, and electrostatic events.
External sources
- Lightning (direct and induced)
- Utility switching and capacitor banks
- Faults on the MV/LV network
Internal sources
- Large motor starting / stopping
- Inductive load switching
- Arc faults and poor contacts
Mapping sources to protection
Entrance SPDs focus on external energy. Local SPDs near panels and equipment address residual and internally generated transients.