Professor Anastasia S. Safigianni

Low Voltage Installation Protection


  • Three phase networks without operation grounding and directly grounded networks
  • Networks with large insulation resistance and ungrounded neutral
  • Networks with small insulation resistance and ungrounded neutral
  • Networks with grounded neutral
  • Protective grounding using large grounding resistance
  • Determination of the necessary protective grounding resistance
  • Non metallic fault to the case of a grounded appliance
  • Neutralization of three phase networks
  • Regular neutralization
  • Non metallic fault to the case of regularly neutralized appliances
  • Irregular neutralization without earth conductor
  • Regular neutralization with earth conductor
  • Phase to earth fault
  • Neutral break in networks without earth conductor
  • Neutral break in networks with earth conductor
  • Interchange between phase conductor and neutral in networks without earth conductor
  • Protection with leakage - current circuit - breakers (LCCB) and leakage - voltage circuit - breakers (LVCB)
  • LCCB with nominal leakage - current IΔn =0,5A
  • Maximum grounding resistance for protection with an LCCB 0,5 A
  • LCCB with nominal leakage - current IΔn = 30 mA
  • Maximum grounding resistance for protection with an LCCB 30 mA
  • Protection with an LCCB 30 mA without grounding
  • Protection with an LVCB. Determination of the limit value Rk
  • LVCB and direct grounding