Apr 2013
Electricity Distribution
TP 22 LV Fault Locator
Apr 2013
Electricity North West Limited
Electricity North West Innovation Team
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Innovation Funding Incentive
LV & 11kV Networks
TP-22 units, and their predecessors the T-P20 and T-P21, have been used to locate many intermittent faults on the LV network, some of which had existed for many months and been impossible to locate with previously available fault location instruments. All of these fault locations were carried out by a small number of specialists using the remote interrogation features of the T-P2X Master Station software. As the number of instruments in service increases it is becoming more difficult to ensure that the status of units and the integrity of the communication channels are checked regularly. If this is not done systematically it is possible for valuable fault events to be over-written or for problems with a unit, or its communication channel, to go undetected until an interrogation is attempted after a fault has occurred.

When first introduced the TP-20 operated purely as a triggered TDR device with a limited range of functions. The TP-22 now includes the Travelling Wave (TRS) mode of operation whilst still providing triggered TDR, but with a wider range of functions. Alone, or in combination with TV-22, the TP-22 forms a 3 phase Voltage Gradient System (VGS) with remote control and interrogation. Depending on the situation, the 3 modes of operation can often be used simultaneously, or sequentially, to improve the chances of achieving a successful fault location or to resolve an ambiguous result on a multi-branched cable.

As awareness of the usefulness of the TP-22 has grown there has been an increase in the number of non-specialist users requiring a simplified means of control and interrogation, preferably with a degree of automatic analysis and validation of the acquired data. Against the above background it is now appropriate to re-evaluate how the full potential of the T-P22 and TV-22 units can be realised through the development of a new Master Station software package which will reduce the need for manually initiated interrogation by specialist operators. A number of T-P22 would be purchased to trial the developed firmware and software.

The Kehui TP-22 is used to locate the most elusive intermittent faults on the ENWL LV network, this project collaborated with Kehui to introduce a number of further functional developments and also Nortech to enable the TP-22 data to be viewed over the iHost Platform.

The main features of the proposed development package are:

  • Regular automatic Logging and polling of specified units

  • Configuration tool to provide investigation into possible methods of automatic fault location using estimation of impedance to fault from voltage measurements

  • Conversion of impedance to fault into distance to fault based on cable parameters and source transformer rating

  • Estimation of distance to fault using TRS data

  • Estimation of distance to fault using TDR data

  • Create automatic fault location log giving results of successful locations.