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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A SumoBrain Solutions Company. Sakis Meliopoulis, and A. A fault distance locator as claimed in claim 8, further comprising a high voltage capacitor interconnected between said pulse generator unit and said cable. This propagation speed will also be stored and subsequently used in calculating the distance to the fault. The time delay between the sending pulses and their associated reflected pulse signals are monitored for approximately to microseconds after each burst and the corresponding data is stored in the random-access memory of the controller for processing after the fault has been cleared.
Therefore, it is intended that this invention not be limited to the particular embodiment disclosed as the best mode contemplated for carrying out the invention, but that faul invention will include all embodiments falling within the scope of the appended claims.
Fault distance locator for underground cable circuits – Dipl.-Ing H. Horstmann GmbH
The most current of the pulse signals will be stored in the random-access memory to be used and defining a undergtound pulse signal for calculating distance when a fault occurs.
It is another object of the present invention to provide a fault distance locator for underground cable circuits for pinpointing the location of the fault with a high degree of accuracy, without being affected by the arc voltage appearing at the cable fault. As can be seen, the three inputs on the lines 48, 62 and 68 corresponding to the respective voltage, current and pulse signals are applied to the multiplexer A fault distance locator for underground cable circuits for calculating more accurately the location of a olcator fault includes a pulse generator unit for injecting a series of chirped pulse streams into the faulted cable shortly after the cable fault has been established.
With particular reference to FIG. Then, a set of 4, to 5, data points will be sampled for each pulse and stored in the random-access memory.
The voltage and current on the cable are continuously monitored every few milliseconds or several times a cycle for 60 Hz by the controller 30 to determine if a fault has occurred. Fault distance locator for underground cable circuits.
Alternatively, instead of the chirped pulse stream the pulses may be in the form of a pulse stream having a single frequency or undergrounnd frequencies. Reed issued on Sep.
A tripping signal is generated by a logic unit when the fault position and the apparent fault resistance are within the limit values, respectively.
These measured values are low pass filtered and then converted from an analog to an instantaneous digitized current and voltage values. Further, the pulse stream of the single frequency can be made to have a changing amplitude. This digitized voltage signal on the line 54 is then delivered to the microprocessor in the computer controller 30 for processing and then stored in predetermined addresses in the random-access memory.
For example, there is a commercially available prior art reflection system using a memory radar which is manufactured by VON Corporation of Birmingham, Ala. Faults sometimes develop, such as when the cable is punctured creating a short circuit between the conductor and the concentric neutral, which require the repair or replacement of the cable or a portion thereof.
When a large increase in current occurs, such as at time T1 in FIG. It is preferable to take approximately 4, to 5, samples at the sampling rate of 20 MHz so as to produce a cumulative sampling time of between to uS. When a cable failure occurs, a undergrpund or circuit breaker or other circuit interrupting or protective device will be tripped so as to cause a circuit interruption.
A controller device is responsive to the fault-current occurrence signal and the fault-voltage occurrence signal for initializing the pulse generator to send a series of chirped pulse streams into the faulted cable at a high sampling rate for a predetermined amount of time subsequent to the fault and prior to a fault interruption in order to obtain reflected pulse signals.
undergrounv These pulses are injected onto the cable every few hundred microseconds or less until either the fault is cleared at time T2 in FIG. The correlation process is started in block upon the detection of a fault. A set of 4, to 5, data points will be sampled and stored in the random-access memory, and the controller will calculate the time to the reflection from the end of the cable.
The current of the underground cable fauot involved is detected or monitored by a current transformer 24 C. The prior art patents are believed to be best exemplified by U.
This pulse signal provides information concerning the speed of propagation of the cable and thus affects the distance calculation to the fault. Click for automatic bibliography generation. 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 of the fault so that the appropriate repairs can be made in order to restore the undedground to their previous normal operation.
The fault distance locator includes a pulse generator unit for undergroknd a series of chirped pulse streams into the faulted cable shortly after the cable fault is established. A high power, high frequency pulse generator unit 28 is used to provide a pulse stream of high frequency pulses onto the underground cable 16 via a high voltage capacitor CAP.
One end of the resistor R1 is joined to the center conductor 18 at node A, and the other end of the resistor R1 is joined to one end of the resistor R2 at node B. This procedure just described is commonly followed by virtually all of the electric utilities in the United States and involves about a 2 to 4 hour period of time to be accomplished.
Consequently, full restoration of service is provided during the time when the faulted cable section is being repaired.