Electricity: measuring and testing – Fault detecting in electric circuits and of electric components – For fault location
Patent
1987-01-16
1988-10-04
Eisenzopf, Reinhard J.
Electricity: measuring and testing
Fault detecting in electric circuits and of electric components
For fault location
324530, 324520, 340743, G01R 3108
Patent
active
047758392
DESCRIPTION:
BRIEF SUMMARY
The invention concerns a control apparatus for the electronic detection of fault locations in overhead alternating current transmission lines in which power losses occur through corona discharges.
In electric transmission lines, particularly high voltage overhead transmission lines, relatively small damage to the conductors, insulators and earthing (grounding) means lead to appreciable current losses. However, it is of particular significance that such damage tends to increase or propagate and may become the cause of short-circuits which leads to a switching-off of the network portion in question and in certain circumstances may even have the consequence of still greater damage to the network causing correspondingly greater expenditure in repair. Hence for reliable operation it is necesary to keep the condition of overhead transmission lines under control and to detect any fault locations arising at an early stage as far as possible so that the fault may be rectified in good time and still at a relatively low cost before greater damage to the network develops from them.
In general the monitoring of overhead transmission lines is undertaken by experts who periodically drive or walk along the overhead transmission lines and check temporarily switched off conductor sections visually for fault locations in which mostly the need to climb up on high voltage masts or poles cannot be avoided. Such a monitoring of overhead transmission lines is not only expensive in time and costs but also make greater demands on the controlling personnel who must have a sufficiently good physical constitution as well as an adequate technical experience. Furthermore, the possibility cannot be excluded that despite such a careful and knowledgeable monitoring, fault locations which hardly show themselves may be overlooked and may lead to greater network damage.
For many years now attempts have been made to obviate this demanding and uneconomic visual monitoring process and to replace it with another process which permits detection of fault locations in alternating current overhead transmission lines from a distance and while a transmission line remains switched on, in a more rapid and reliable manner and which in addition affords a reliable network monitoring with fewer controllers and above all with controllers who are not placed under such high requirements.
The recognition that conductor, insulation and coupling defects cause local heating-up of the relevant plant parts has given rise to the idea of thermographically recording the critical positions of overhead transmission lines. But this control procedure is also relatively expensive.
Furthermore, it has been recognized that the relevant fault positions of overhead transmission lines give rise to current losses through discharges, particularly corona discharges which are sources of electromagnetic radiation the frequencies of which are considerably higher than the line frequency and are not in any harmonic relationship to the line frequency. This ascertainment has led to an electronic monitoring process in which the electromagnetic field along the overhead transmission line is monitored for irregularities by means of an antenna, an amplifier device and an oscilloscope. Apparatus of this type has been disclosed in U.S. Pat. No. 4,006,410. In this known apparatus the high frequency signals received by the antenna are subjected to Fourier analysis by modulation with an internal signal of variable frequency and with the aid of band filters and line traps. For this, however, a relatively high technical expenditure is necessary, which causes significant costs and gives rise to an increased susceptibility to faults in the apparatus.
The present invention has accordingly the aim to provide a technically simpler and less fault-prone control apparatus for the electronic detection of fault locations in overhead transmission lines.
The aim of the invention is achieved by the provision of electronic control apparatus defined in the claims. In the control apparatus according to the invention
REFERENCES:
patent: 3173086 (1965-03-01), Kresge
patent: 4006410 (1977-02-01), Roberts
patent: 4356443 (1982-10-01), Emery
Hubacher Peter
Kosina Bohumil
Talacko Radovan
Eisenzopf Reinhard J.
Korona Messtechnik Gossau
Solis Jose M.
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