Mechanical stress can be destructive, especially inside power enclosures where high current peaks may occur and high fault currents can flow for up to one second.
Thermal stress is harmful for plastic materials, such as cable insulation. Temperature rises, which occur during faults, can shorten the life of cables. Shorter life means more money must be invested in service, maintenance and renovation.
A plant where zone selectivity is implemented ensures fast fault clearing at every level and prevents both mechanical and thermal stress.