JPS6161068A - Detecting method of partial discharge occurrence position in cable connection part - Google Patents

Abstract

PURPOSE:To measure the magnitude of discharge at a discharge position by detecting an electric pulse and a sound wave of a discharge sound generated by the discharge in a cable connection part and measuring the detection time difference between both, and spotting the discharge position from the time difference and the propagation speed of the sound wave. CONSTITUTION:A cable 1, connection part 2, pulse sensor 3, ultrasonic sensor 4, current transformer 5, computing element 7, etc., are provided. If discharge is caused in the connection of the cable 1, the electric pulse originating from the discharge is detected by the sensor 3. At this time, a current flowing through an earth wire varies and this variation is detected by the current transformer 5. This electric pulse is inputted from an amplifier 6 to the computing element 7. Then, the discharge generates a discharge sound over the entire frequency range in addition to said electric pulse, and the ultrasonic wave of it is detected by the sensor 4 and inputted to the computing element 7. This electric pulse and ultrasonic wave signal are so detected that the ultrasonic wave signal is detected a specific time after the electric pulse is detected. Then, the computing element 7 measures the detection time difference from the rising of the electric pulse to the rising of the ultrasonic wave to find the occurrence position of the discharge.

Description

[Detailed Description of the Invention] [Technical Field of the Invention] The present invention relates to a method for detecting the position of partial discharge within a cable connection, and particularly relates to a method of locating the position of discharge using electric pulses and sound waves generated by electric discharge. do.

[Technical Background of the Invention] Generally, when the insulation properties of a cable are degraded, electric discharge begins to occur locally even within the connection portion of a cable. That is, the connecting portions are insulated with insulating tape, insulating compound, etc. and fitted with steel pipes, etc., and their insulating properties gradually deteriorate. The connection length of long-distance cables is 360 to 750M, and a conventional method has been known to apply an ultrasonic sensor to this connection and detect how much partial discharge is occurring within the connection. ing.

This detects the ultrasonic band of the discharge sound generated by discharge.

[Problems with the background art] However, the above method only detects whether or not a discharge occurs within the cable connection, and cannot measure the location where the discharge occurs. The drawback is that the actual size of the discharge cannot be determined.

[Object of the Invention] The present invention has been made in view of the above-mentioned conventional difficulties.The present invention detects electric pulses and sound waves of discharge sound generated by discharge in a cable connection part, measures the detection time difference between the two, and detects the electric pulse and the sound wave of the discharge sound. The object of the present invention is to provide a method for detecting a partial discharge occurrence position in a cable connection part, which measures the magnitude of the discharge at the discharge position by locating the discharge position from the sound wave propagation velocity.

[Summary of the Invention] A method for detecting a partial discharge occurrence position in a cable connection part according to the present invention to achieve such an object detects an electric pulse caused by a partial discharge generated in the cable connection part, and detects an electric pulse generated by the discharge. Detect the sound wave of the discharge sound, measure the detection time difference between the electric pulse and the sound wave, and determine the position of occurrence of partial discharge in the cable connection part from the detection time difference and the propagation speed of the sound wave at the connection part of the cable. It is something to locate.

[Embodiments of the invention] Preferred embodiments of the present invention will be described below with reference to the drawings.

The method of detecting the position of partial discharge in a cable connection section according to the present invention is actually TQ'ed using a device as shown in the drawings. In the figure, a pulse sensor 3 is attached to a predetermined location of the connection part 2 of the cable l.
and an ultrasonic sensor 4 (a sensor in an audio frequency band can also be used) is brought into contact. The pulse sensor 3 is grounded, and the ground wire is provided with a current transformer 5 coupled with a ferrite core. The current transformer 5 is connected to the arithmetic unit 7 via an amplifier 6, and the ultrasonic sensor 4 is also connected to the arithmetic unit 7 via an amplifier 8.

In the device having such a configuration, first, when a discharge occurs within the connection portion 2 of the cable 1, the pulse sensor 3 detects an electric pulse due to this discharge. At this time, the current flowing through the ground wire changes, and the current transformer 5 detects this change. The electric pulse resulting from the current change detected by the current transformer 5 is amplified by the amplifier 6 and input to the arithmetic unit 7. Next, in addition to the generation of electric pulses, the discharge emits discharge sound in almost the entire frequency range,
Of these, the ultrasonic waves are detected by the ultrasonic sensor 4 and input to the amplification product calculator 7 by the amplifier 8 . Due to the difference in propagation speed between the electric pulse and the ultrasonic signal in the connecting member, that is, the insulator (not shown) in the connection part 2, the ultrasonic wave is generated after a certain period of 1=3 after the electric pulse is detected. A signal is detected. Then, the computing unit 7 measures the detection time difference from the rise of the electric pulse to the rise of the ultrasonic signal.

On the other hand, in the computing unit 7, since the propagation velocity of the sound wave and the thickness of the insulating layer for each of the insulators in the connection part 2 are known, the data is entered manually, and the data is calculated by multiplying these and the detection time difference. The location where the discharge occurs is determined and located.

Once the partial discharge occurrence position within the connection part 2 of the cable 1 is determined in this way, the magnitude of the discharge at the discharge position can be investigated from the shape and dimensions of the connection part 2 and the attenuation characteristics of the ultrasonic waves. That is, this makes it possible to appropriately deal with partial discharges, and because the magnitude of discharge can be corrected, insulation deterioration within the connection portion 2 can be properly diagnosed.

[Effects of the Invention] As is clear from the above embodiments, according to the present invention, electric pulses generated by discharge in a cable connection part and sound waves of discharge sound are detected, the detection time difference between the two is measured, and the detection time difference between the two is measured. By locating the discharge position based on the sound wave propagation velocity of the connecting member, the magnitude of the discharge at the discharge position can be measured, and the connecting member can be optimized and safety can be improved.

[Brief explanation of the drawing]

The drawing is an explanatory diagram showing a method for detecting a partial discharge occurrence position within a cable connection section according to the present invention. DESCRIPTION OF SYMBOLS 1... Cable, 2... Connection part, 3... Pulse sensor, 4... Ultrasonic sensor, 5... Current transformer, 7... Arithmetic unit.

Claims (1)

[Claims] At the same time as detecting the electric pulse due to the partial discharge generated in the cable connection part, the sound wave of the discharge sound generated by the discharge is detected, the detection time difference between the electric pulse and the sound wave is measured, and the detection time difference and the connection of the cable are detected. 1. A method for detecting a partial discharge occurrence position in a cable connection part, comprising locating a partial discharge occurrence position in the cable connection part from the propagation velocity of a sound wave in a member.