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Projects: Projects for Investigator
Reference Number NIA_SSEPD_0023
Title Fault Passage Indicators for Sensitive Earth Faults
Status Completed
Energy Categories Other Power and Storage Technologies(Electricity transmission and distribution) 100%;
Research Types Applied Research and Development 100%
Science and Technology Fields ENGINEERING AND TECHNOLOGY (Electrical and Electronic Engineering) 100%
UKERC Cross Cutting Characterisation Not Cross-cutting 100%
Principal Investigator Project Contact
No email address given
Scottish Hydro Electric Power Distribution plc (SHEPD)
Award Type Network Innovation Allowance
Funding Source Ofgem
Start Date 01 December 2015
End Date 01 January 2018
Duration 27 months
Total Grant Value £256,000
Industrial Sectors Power
Region Scotland
Programme Network Innovation Allowance
Investigators Principal Investigator Project Contact , Scottish Hydro Electric Power Distribution plc (SHEPD) (99.999%)
  Other Investigator Project Contact , Southern Electric Power Distribution plc (SEPD) (0.001%)
Web Site http://www.smarternetworks.org/project/NIA_SSEPD_0023
Objectives 1. Determine, from testing, that the revised FPIs successfully meet the required standard2. Train operational staff in the correct use of the revised FPIs3. Perform a field trial with trained operational staff4. Monitor and evaluate the reduction in customer hours lost per Customer affected by an SEF fault in the trial area when compared to previous years. This project will be successful if we are able to determine the ability of the revised FPI to reduce CMLs due to SEF faults.
Abstract Many rural areas of GB are supplied by overhead lines operating at 11,000 to 33,000 volts, these are cheaper to construct and operate than underground cables operating at the same voltage. These overhead lines do not supply customers directly in most cases. They are usually connected to pole mounted transformers which change the voltage to 230v single phase or 400v three phase, for the final supply to customers. The overhead lines are usually operated with a section of line fed via a single circuit breaker at a primary substation. There are often switching points between adjacent circuits, where the geography allows this thereby allowing electricity to be re-routed via a different route to avoid faulted sections of overhead line. Overhead lines are fitted with protection systems which detect faults which may damage the network due to high fault currents, and earth faults which can cause unsafe conditions to occur on the network. In order to detect the lowest earth fault currents, a system known as sensitive earth fault (SEF) protection is used. SEF can detect fault currents of as low as four amps (4A) in some cases which helps to prevent problems with broken wires remaining live on the ground. In order to locate a fault on an overhead line after the protection system has operated to isolate the faulty section of the network, a number of techniques are used. These techniques range from patrolling of the overhead line by our staff, trying to re-energize the overhead line in a different configuration by opening and closing of air insulated switches and disconnecting links and by deploying fault passage indictors (FPI). These require that the line be re-energized and to allow the protection system to operate again in the same way as re configuring the line. However several tests can be carried out at the same time by using more than one fault passage indicator. For many faults FPIs significantly improve the speed at which a DNO can locate a fault and then if feasible restore supplies to customers from alternative routes and then carry out repairs. However the detection of faults at very low fault currents, as seen when only the SEF protection operates at Primary sub stations, or at pole mounted circuit breakers is not matched by the current generation of fault passage indicators. This means that for some earth faults with low fault current that we cannot locate the fault using fault passage indicators. This means that we have to locate the fault by operation of switches and disconnecting links, before re-closing the circuit breaker which originally tripped. In general this results in more interruptions to customers and an increased time to locate a fault, when compared to the time taken to locate faults, where FPIs operate satisfactorily because of higher fault currents. While accounting for only 6% of faults on the SHEPD network SEF faults account for 11. 8% of the Customer Interruptions and 8. 3% of the Customer Hours lost. A technical method is proposed and it involves carrying out tests on a revised FPI from Bowden Brothers which has been modified to detect SEF faults down to 4A. The tests will be performed at the Power Networks Demonstration Centre (PNDC) in Cumbernauld to ensure that the revised device has significantly improved sensitivity over our current range of FPIs. A trial of this device will be carried out in one of our Regions for a year to establish if it can successfully reduce the time takento locate and isolate difficult to find SEF faults.Note : Project Documents may be available via the ENA Smarter Networks Portal using the Website link above
Publications (none)
Final Report (none)
Added to Database 14/08/18