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Automatic Location of Arc-faults through Remote Monitoring (ALARM)

Funding mechanismNetwork Innovation Allowance (NIA)
DurationSep 2019 - May 2022
Estimated expenditure£493K
Research areaNew Technologies and Commercial Evolution
  • August 2021

    The main focus this month has been the continued selection, verification and monitoring of the more active sites at Victoria Road and Fairefield Crescent. It…


  1. Test the feasibility of a technical alternative and lower cost fault locating device.
  2. Derive insight into the potential to more widely and cost-effectively deploy such monitoring equipment to feeders showing early indications damage (e.g. transient fuse operations).


It is widely understood that underground LV networks regularly experience pecking faults – short duration arc faults typically caused by water ingress at partially damaged cable sections or connection/transition points in the network. Such events progressively damage the cable system, and can lead to the development of fuse-operating transitory faults (with customers off for the time required to change fuses). This can then develop to permanent faults with longer customer outages occurring for reactive fault location and repair to be completed.

Fault data from the last four regulatory years shows there have been 331 LV feeders with four or more transient fuse incidents in the East Midlands region of WPD. In total, 526 fuse incidents occurred after there had already been four incidents.


The project proposes to test the feasibility of a technical alternative and lower cost fault locating device. This will be achieved by WPD providing a real-world testing opportunity, and by the manufacturer using this opportunity to demonstrate (and tune at their cost) the fault locating device’s operation.

The project proposes to install substation monitors capable of identifying and locating distance to cable arc-faults. Each monitor consists of Rogowski Coil based phase-current sensors (for up to five LV feeders) together with voltage taps, connected to a Metrology and Communications Unit (MCU) which processes the sensor data and generates and logs substation loading and condition parameters.

Each monitor will capture and retain voltage and current waveforms from the monitored LV feeders when pre-set triggers are activated (e.g. rate of change of voltage or phase current). The captured waveforms will be forwarded via a GPRS/mobile data connection to a processing data centre where inductance and resistance values for the faulting network will be estimated. The estimated value of inductance will then be used to establish a distance to fault estimate.