Smartdust is a concept developed by the University of California that is based on a self-configuring wireless sensor network, capable of transmitting low bandwidth information in a series of short hops. Data acquired and transmitted from sensors is relayed through a gateway for data interpretation. SP led a feasibility study into the use of this technology for detecting the passage of fault currents on 11kV overhead line networks.

Following on from this work, a collaborative project was scoped with SP to develop a product based on this principle for the remote signalling of fault passage indication on overhead line networks.

Objectives

Fault Passage Indicators (FPIs) are pole mounted sensors that detect the passage of fault current in an overhead line via disturbances in the electro-magnetic field. Presently FPIs indicate the passage of a fault current via LED or beacon on the unit itself. This is used by linesmen on patrols to identify the source of the fault.

A cheap and reliable method of collection of fault passage indication data, a centralised location for overhead line faults would significantly reduce the time required to resolve faults on the network and consequently reduce Customer Minutes Lost (CML) associated penalties. This technology would be especially suited to transitory fault location.

Significant analysis has been undertaken on the deployment characteristics of GSM/GPRS fault passage indicators Vs radio communicating sensors, using fault histories. The analysis is considering the relationship between sensor cost, deployment penetration and improvement to CML figures.

The key conclusion is that a cheap, low power semi-mesh radio based system:

• Allows a much higher percentage of locations of be monitored economically than any other option, across all price points and time savings

• Offers a much higher NPV than any other option.

Owing to these factors, a significantly higher percentage of network can be monitored (from 10% for GSM devices to above 70% coverage for radio sensors), increasing the likelihood that they will be targeting faults (rather than solely focussing on worst performing circuits).