Electric Power System Fault Indicator for Overhead Radial Distribution Lines FT-FI1

Overhead Radial Distribution Lines

On long-distance 10kV or 35kV overhead radial feeders passing through mountains, forests, or rural areas, a lightning strike or animal contact may cause a transient or permanent fault. When a fault indicator is clipped onto each phase conductor at key branch points (e.g., every 2-3 km or at sectionalizing switches), the device displays a bright LED flash only on the downstream side of the fault. Linemen drive to the first flashing indicator and inspect only the short section ahead, rather than patrolling 20 km of line. This directly cuts outage time from 4 hours to under 30 minutes, dramatically improving SAIDI and CAIDI utility metrics.

Underground Cable Loop Networks

Underground cables in urban CBDs or industrial parks are prone to breakdowns caused by excavation damage, water tree aging, or thermal runaway. Unlike overhead lines, cable faults cannot be spotted visually from the street. By mounting fault indicators at each cable joint or on the panel of Ring Main Units (RMUs), the device captures the transient fault current signature when a cable section fails. The display turns red or flashes an LED, allowing crews to pinpoint the exact 200-meter segment between two joints. Without such indicators, utility teams would need to disconnect the entire loop, perform insulation resistance tests at multiple points, and potentially dig randomly—an expensive and time-consuming process.

Mixed Overhead & Cable Hybrid Feeders

A typical suburban feeder often starts with overhead lines from the substation, transitions into underground cables near residential clusters, then returns overhead. When a fault occurs in the underground portion, upstream overhead reclosers may trip and reclose successfully if the fault is transient. However, a permanent cable fault requires immediate isolation. Installing fault indicators with remote communication at the overhead-to-cable transition points provides dispatchers with real-time fault data. The SCADA system immediately displays which phase and which transition point experienced the overcurrent. Dispatchers can then remotely open sectionalizers to isolate only the cable block, keeping the rest of the overhead line energized and maintaining power to healthy customers.

Switchgear & Distribution Panel Monitoring

Within indoor metal-clad switchgear or secondary distribution panels, manual fault finding among dozens of outgoing feeders is dangerous and slow. Each circuit breaker panel can be equipped with a panel-mounted fault indicator connected to the relay or CT outputs. When a downstream fault trips the breaker, the corresponding indicator's mechanical flag pops from white to red, precisely identifying which feeder caused the trip. This eliminates the need to check each feeder's protection relay settings or guess which cable experienced a fault. For industrial plants with critical uptime requirements (e.g., semiconductor fabs or hospitals), this immediate identification reduces mean time to repair (MTTR) and allows maintenance crews to focus on the correct cable trench immediately.