RMU - Ring Main Units

SFA-RM units are designed to supply reliable energy and protect electrical equipment in secondary distribution networks up to 36 kV. SFA-RM units are the best solution for indoor/outdoor distribution substations as their compact design makes them suitable for various network applications such as transformer substations, wind power plants, renewable energy projects, industrial zones, etc. SFA-RM SF6 gas insulated units offer the following types :

Ring Main Unit , type SFA-RM , 12 kV

Technical Specifications:

  • Gas insulated Ring Main Units
  • Rated voltage = 12 KV
  • Normal current = 630 A
  • Short circuit withstand current: up to 21 kA.
  • Short circuit duration: 3 sec
  • Power frequency Withstand voltage = 38 kV r.m.s
  • Lightning Impulse withstand voltage Up = 95 kV peak
  • Internal arc classification: A (FLR)
  • Degree of protection: IP41 for indoor / IP54 for outdoor


Ring Main Unit , type SFA-RM , 17.5 kV

Technical Specifications:

  • Gas insulated Ring Main Units
  • Rated voltage = 17.5 KV
  • Normal current = 630 A
  • Short circuit withstand current: up to 21 kA
  • Short circuit duration: 3 sec
  • Power frequency Withstand voltage = 38 kV r.m.s
  • Lightning Impulse withstand voltage Up = 95 kV peak
  • Internal arc classification: A (FLR)
  • Degree of protection: IP41 for indoor / IP54 for outdoor


Ring Main Unit , type SFA-RM , 36 kV

Technical Specifications:

  • Gas insulated Ring Main Units
  • Rated voltage = 36 KV
  • Normal current = 630 A
  • Short circuit withstand current: up to 25 kA.
  • Short circuit duration: 1 sec.
  • Power frequency Withstand voltage (common value) = 70 kV r.m.s
  • Power frequency Withstand voltage (across the isolating distance) = 80 kV r.m.s
  • Lightning Impulse withstand voltage (common value) = 170 kV peak
  • Lightning Impulse withstand voltage (across the isolating distance) = 200 kV peak
  • Internal arc classification: A (FLR)
  • Degree of protection: IP54 (indoor & outdoor applications)


SFA-RM Smart Ring Main Units

Technical Specifications:

  • Gas insulated Self-power RMU
  • Rated voltage = up to 36 KV
  • Normal current = 630 A
  • Short circuit withstand current: up to 25 kA.
  • Short circuit duration: 1 or 3 sec
  • Loss of service continuity category (LSC) LSC2A-PM
  • Internal arc classification: A (FLR)
  • Degree of protection: IP41 for indoor / IP54 for outdoor
  • Relative Humidity : 100%
  • 3G/4G Communication, VPN Security “IPsec”
  • Accurate Measurements for voltage and current in all switching elements