Internal MV circuits

From Electrical Installation Guide

Internal MV circuits are dedicated to the supply of the secondary MV/LV substations dispersed in the installation. They are three typical principles commonly used for this purpose Fig. D11:

  • Single feeder
  • Dual feeder
  • Open ring
Fig. D11 – Single feeder, Dual feeder, Open ring

Comparison of these three typical principles of internal distribution is given Fig. D12.

Fig. D12 – Comparison of the typical internal circuits
MV circuit configuration
Characteristic to consider Single feeder Open ring Dual feeder
Site topology Any Single or several buildings Single or several buildings
Power demand Any > 1250kVA > 2500kVA
Disturbance sensitivity Long interruption acceptable Short interruption acceptable Short interruption not acceptable