12 Dec UNDERGROUND CABLE FAULT DETECTION UNDER ESTEEM By entering the distance between the manholes, via the propagation. 2 Apr A distance fault locator for an underground cable for calculating .. A report of this work is described in the paper entitled “An Advanced. ACKNOWLEDGEMENT Accomplishment of this project report is a result of my and on-line fault detection and location system for underground distribution power cable. the fault current to be used in locating the fault distance from the control room. . 9 ii) The overall cost of the locator unit can be much higher than the.
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The phase voltage and the phase current or changes in the phase current are measured on the occurrence of a fault. In addition, the shape of the pulses may not only be square but can also be sinusoidal or triangular in form.
From the foregoing detailed description, it can thus be seen that the present invention provides an improved fault distance locator for underground cable circuits for calculating accurately the location of a cable fault. A SumoBrain Solutions Company. In addition, many modifications may be made to adapt a particular situation or material to the teachings of the invention without departing from the central scope thereof.
It is generally this latter event that occurs first. This filtered voltage signal is then passed through an amplifier 44 to a first input of an analog multiplexer 46 via line This is accomplished in the present invention by the use of a pulse generator for injecting a series of chirped pulse distacne into the cable shortly after the occurrence of the cable fault.
Sakis Meliopoulis, and A.
The multiplexer is switched periodically so that these various input signals to be monitored can be sampled at a predetermined time interval i. These pre-fault pulses are also passed through the voltage divider 26 and exist at the node B.
The overhead power lines from a source not shown are comprised of a high voltage wire or cable 12 and a neutral wire After the steps of determining of an existence of a cable fault and determining the approximate location of such fault, linemen or repairmen later return in several days to find the exact and actual location unnderground the fault so that the appropriate repairs can be made in order to restore the circuits to their previous normal operation.
Then, a locatog of 4, to 5, data points will be sampled for each pulse and stored in the random-access memory. A fault distance locator reporrt claimed in claim 7, wherein the sampling rate is at a frequency between 5 to 50 MHz for a period of 50 to microseconds. It was determined that variability of the arc voltage will typically exist within each half-cycle of arcing.
As is known, the surge impedance will affect the speed of propagation and thus the delay distancw. In other words, the voltage and the current are measured at both ends of the faulted line and some algorithm would make the calculation of the distance to the fault based upon the measurements.
Consequently, full restoration of service is provided during the time when the faulted cable section is being repaired. In order to locate the frequency spectrum of this resulting data distanve of FIGS.
The center conductor 18 is suitably connected to the high voltage wire 12, and the concentric neutral 22 is suitably projdct to the neutral wire The distznce controller preferably includes a microprocessor, a ffault memory ROM for storing a program executed by the microprocessor, and a random-access memory RAM for storing variables used in data processing and computations.
Method and means for monitoring faults in an electric power system and the like. The first output voltage on the line 58 from the current transformer 24 is proportional to the current in the high voltage phase wire or conductor Next Patent Determining contact This second output voltage is also low-pass filtered so as to pass only the fundamental component 60 Hz and the lower order harmonics.
The second output voltage on the line 42 from the voltage divider repodt is proportional to the voltage in the high voltage phase wire or conductor The fault distance locator can be installed generally on an underground residential distribution URD terminal pole which connects the cable circuit to an overhead power source or may be located alternatively on a switching cubicle.
A pulse generator is provided for injecting periodically a chirped pulse stream into the cable prior to the occurrence of the cable fault in order to obtain a reference pulse signal. The major characteristic of the cable which is changed due to the cable environment will be the dielectric coefficient of the insulation layer 20 since it is greatly temperature dependent.
It should be noted that this sampling rate is controlled by the computer controller 30 via line This pre-fault pulse injection at the predetermined intervals is used to enhance the accuracy of the fault distance calculation.
Fault distance locator for underground cable circuits – Dipl.-Ing H. Horstmann GmbH
There still exists another prior art system which utilizes a single-ended impedance-based monitoring of the fault parameters to calculate the distance to a fault with the aid of a microprocessor. A fault distance locator as claimed in claim 8, further comprising a high voltage capacitor interconnected between said pulse generator unit and said cable. Further, prior to the fault locating step the cable is to be de-energized, tested for potential, and grounded so as to remove the charge due to the cable capacitance.
Referring now to FIG. It is an object of the present invention to underround a fault distance locator for underground cable circuits and a method for the same for calculating more accurately the location of a cable fault from a source-connected monitoring location in an efficient and effective manner.