Underground & Cable Fault Indicators
Locate the faulted cable section without opening every cabinet.
On an underground residential loop there is nothing to patrol. A fault trips the head of the circuit and the crew works the loop cabinet by cabinet, switching and re-energizing until the fault re-appears, which stresses the healthy cable every time. A cable fault indicator ends that. Each device reports whether fault current passed its point, so the faulted section is identified before anyone opens a door.
The range covers 6 kV to 35 kV cable networks with two sensor types: a rigid bracket sensor where there is room to work, and a flexible Rogowski-coil sensor for tight cable compartments where a solid sensor will not fit around the cable and its terminations. Both detect short-circuit and earth faults, both drive a local LED for the crew standing in front of the cabinet, and both report to a local concentrator that carries the alarm to SCADA over cellular using IEC 60870-5-101, IEC 60870-5-104, DNP3.0 or Modbus.
Why it matters
Fault-location time on a radial cable feeder is the dominant term in SAIDI for underground networks. Sectionalizing by indication instead of by trial re-energization removes hours from the restoration curve.
Every trial re-energization drives another fault current transient through healthy cable and joints. Indication-based switching avoids that and protects the remaining service life of the circuit.
The flexible Rogowski-coil sensor installs in RMU and cable-cabinet compartments where clearance is the limiting factor, so retrofit does not require new switchgear.
The same concentrator and the same protocol set used by the overhead indicators serve the underground fleet, so one integration into the DMS covers both.
Ratings
Application voltage: 6 kV to 35 kV cable networks
Sensor types: Rigid bracket sensor and flexible Rogowski-coil sensor for tight cable compartments
Installation: Ring main units, cable distribution cabinets, switchgear compartments and manholes
Detection: Short-circuit and earth fault
Communication: To a local concentrator, then to SCADA over cellular with IEC 60870-5-101/-104, DNP3.0 or Modbus
Indication: Local LED plus remote alarm
Standards
IEEE Std 495
IEC 60255-21
IEC 60529
Applications
Underground residential distribution loops
Urban networks with RMUs and cable cabinets
Industrial campuses with buried MV cable
Reducing fault-location time on radial cable feeders
Questions engineers ask
What is the difference between a bracket sensor and a Rogowski-coil sensor? The rigid bracket sensor is the standard choice where the compartment has room to mount around the cable. The flexible Rogowski-coil sensor wraps into tight cable compartments where clearance is limited, which is common in older ring main units and cable distribution cabinets. Both detect short-circuit and earth faults and report identically.
How do underground fault indicators reach SCADA? Each indicator reports to a local concentrator. The concentrator carries the alarm onward over cellular using IEC 60870-5-101, IEC 60870-5-104, DNP3.0 or Modbus, so the indication lands in the same DMS screen as the rest of your distribution telemetry. A local LED at the device also serves the crew on site.
