GB2349993A

GB2349993A - Fault location

Info

Publication number: GB2349993A
Application number: GB9906528A
Authority: GB
Inventors: John Edward Cunningham
Original assignee: Individual
Current assignee: Individual
Priority date: 1999-03-23
Filing date: 1999-03-23
Publication date: 2000-11-15
Also published as: GB9906528D0

Abstract

A system for locating a fault on a high voltage distribution circuit has a series of sensors B positioned at ring main units. When a fault occurs, the sensors which detect it respond by sending a low frequency signal to a substation receiver A over the high voltage line before a circuit breaker is opened. The receiver is thus able to locate the fault using the information sent by the sensors.

Description

2349993 AUTOMATED FAULT PASSAGE INDICATION SYSTEM (AFPIS)

Introduction

This is a system to be used for locating faults on all Kv electrical distribution circuits.

Principle of Operation Existin-q An 11 Kv ring is shown in Fig 1. There are two substations feeding the ring which has a normally open point. The power flow directions are indicated. At each of the ring main unit points there are load break switches and an 11 Kv to 40OV transformer. Also at this point there is an electromechanical fault passage indicator. Fig 2 shows the result of a fault on the ring. F.P.1 Units number 1,2W have seen the fault, units 4,5,6,7&8 have not seen it.

AFPIS This invention allows a new micro-processor based fault passage indicator to communicate to the substation during the time between the substation circuit breaker having seen the fault and then opening This period of several hundred micro seconds is used by each device to impose a signal into the low voltage side of the transformer. This signal has a narrow bandwidth and is at low frequency and can go through the transformer into the 11 Kv ring. It is then detected by the receiver at the substation. This receiver can then be interrogated in order to assess which two switches border the fault.

1 Summarv The key features of this invention are:- 1. Communications from the ring main units to the substation during the period when the fault is on the system i.e. before the circuit breaker opens.

2. Injection of the signal into the low voltage side of the transformer at the ring main unit.

3. Injection of signals which can go through the transformer without any additional coupling.

11 2, Title: Automated Fault Passage Indicator

Claims

1. An Automated Fault Passage Indicator system comprising a number of remote residual current sensors at 11 Kv Ring Main Units. Communication via low voltage couplers at each sensor for sending information through transformers into the 11 Kv ring and a central receiver for detecting the signals.

2. Communications couplers as outlined in Claim 1 which impose a signal into the low voltage side of the transformer at each Ring Main Unit during the time between occurrence of a fault and opening of the substation source circuit breaker i.e. when the 11 Kv ring is still energised.

3. A central receiver as outlined in Claim 1 which detects the signals as outlined in Claim 2 before the circuit breaker opens.

The receiver. Ithe infoi-n^,iligr, Irom each of the transmitting sensorS'before the current breaker open s i.e. when the system is still live at 11 Kv.

The receiver stores and subsequently analyses the signals in order to identify the units which have responded and hence identify the faulted section of the 11 Kv ring.