CN204287402U - A kind of overground cable shelf depreciation live detection sensor - Google Patents

Abstract

The utility model discloses an electrified detection sensor for partial discharge of an overhead cable, which comprises a signal filter amplifier, a partial discharge current detector with a C-shaped cross section sleeved on the cable, and a partial discharge voltage detector arranged on the partial discharge current detector. . The utility model has the advantages that it is electrically isolated from the measured overhead cable, has high insulation strength, can guarantee the safety of operators, is small in size, light in weight, and is easy to be carried by testing personnel, and the on-site measurement process is convenient. Whether there is partial discharge or not, the propagation direction of partial discharge can also be judged, which greatly reduces the search range and search time of problematic lines.

Description

A live detection sensor for partial discharge of overhead cables

technical field

The utility model relates to a partial discharge charged detection sensor for overhead cables.

Background technique

Since the 1960s, overhead insulated cables (referred to as overhead cables) have been used worldwide. Compared with overhead bare wires, overhead cables have the advantages of good insulation performance, less corrosion, simplified tower structure, and reduced line corridors. Overhead cables have gradually replaced overhead bare wires in my country's urban network transformation. It is widely used in my country's distribution network.

Aerial cables are often erected in densely populated prosperous areas and places with narrow line corridors, fast-growing trees, and serious pollution. Assuming that the environment is more complicated, in addition, due to the characteristics of the structure of the overhead cable itself, overhead cables are prone to lightning strikes, resulting in overhead cable insulation. In severe cases, disconnection accidents are caused; in addition, in special weather conditions, the trees around the corridor grow too fast, causing the branches to lean on the overhead cables, and other external stresses may cause insulation degradation. Partial discharges can occur and eventually cause the entire insulation to fail. Timely detection of line partial discharge points is of great significance to the safe and reliable operation of the distribution network.

The partial discharge detection of overhead cables is one of the effective technical means to detect the insulation state of overhead cables, and has been widely recognized by the industry. The live detection of partial discharge has attracted much attention because it does not require power failure during detection, and the detection data can truly reflect the operating status of overhead cables.

In the past few years, China's power sector has adopted equipment similar to the UltraMet handheld partial discharge detector from British EA Company to detect partial discharge and locate the discharge source on overhead cables by measuring the ultrasonic signal of the line. This method has been verified to be effective through practical application, but consumes too much time and human resources.

Utility model content

The purpose of the utility model is to provide a live detection sensor for overhead cable partial discharge, which can measure whether there is partial discharge in the overhead cable, and if it exists, it can also judge the propagation direction of the partial discharge signal, greatly reducing the search for problem lines range, shortening the time of line inspection.

In order to solve the above-mentioned technical problems, the utility model is realized through the following technical solutions: an overhead cable partial discharge charged detection sensor, including a signal filter amplifier, a partial discharge current detector with a C-shaped cross section set on the cable, and a Partial discharge voltage detector on top of partial discharge current detector.

Preferably, the partial discharge current detector includes a coil winding, a coil frame and a terminal impedance, the coil winding is uniformly wound on the non-magnetic material coil frame by an enameled wire, and the end of the coil winding passes through the center of the frame and connects with the coil winding head The terminals are connected to form a return turn, and the coil winding head and end are connected with a terminal impedance.

Preferably, the terminal impedance is a non-inductive resistor.

Preferably, the partial discharge voltage detector includes an inner copper foil electrode and an outer copper foil electrode, the inner copper foil electrode is arranged inside the partial discharge current detector, and the outer copper foil electrode is arranged outside the partial discharge current detector.

Preferably, the length of the inner copper foil electrode and the outer copper foil electrode are equal, and the width is smaller than the height of the coil frame.

Preferably, both the partial discharge current detector and the partial discharge voltage detector are arranged in an insulating casing.

Preferably, the coil bobbin and one side of the insulating shell have gaps for wires to pass through, and the end of the insulating shell is connected to two BNC connectors, which are respectively connected to the partial discharge current detector and the partial discharge voltage detector.

Preferably, the signal filtering and amplifying unit includes an amplifying unit, a low-pass filter, a high-pass filter and a shielding box.

Preferably, the amplification factor of the signal filtering and amplifying unit is not less than 20 times, the passband low-frequency cutoff frequency of the band-pass filter is not lower than 10kHz, not higher than 100kHz, and the high-frequency cutoff frequency is not lower than 20MHz, not higher than 25MHz .

Compared with the prior art, the utility model has the following advantages: 1. It is electrically isolated from the measured overhead cable and has high dielectric strength, which can guarantee the safety of operators.

2. It is small in size and light in weight, easy to be carried by inspectors, and convenient for on-site measurement.

3. Not only can it measure whether there is partial discharge in the overhead cable, but also can judge the propagation direction of partial discharge, which greatly reduces the search range and search time of the problematic line.

Description of drawings

Fig. 1 is a structural schematic diagram of an overhead cable partial discharge live detection sensor of the utility model;

Fig. 2 is a structural schematic diagram of a partial discharge current detector and a partial discharge voltage detector in an overhead cable partial discharge live detection sensor of the utility model;

Fig. 3 is a structural schematic diagram of a filter amplification unit in an overhead cable partial discharge charged detection sensor of the present invention;

Fig. 4 is a waveform diagram of testing with an overhead cable partial discharge electrification detection sensor of the utility model.

Detailed ways

Referring to Fig. 1, it is an embodiment of a live detection sensor for overhead cable partial discharge of the present utility model, a live partial discharge detection sensor for overhead cable, including a signal filter amplifier 13, a partial discharge current detection device with a C-shaped cross section on the cable A device 11, a partial discharge voltage detector 12 arranged on the partial discharge current detector.

As shown in FIG. 2 , the partial discharge current detector 11 is mainly composed of a coil winding 21 , a coil frame 22 and a terminal impedance 23 .

The coil winding 21 is uniformly and densely wound on the coil frame 22 of non-magnetic material by enameled wire, and the end of the winding passes through the center of the frame and returns to the head end to form a return turn. A terminal impedance 23 is connected at the beginning and end of the winding. The terminal impedance 23 is a non-inductive resistor.

The partial discharge voltage detector 12 is composed of two copper foil electrodes—an inner copper foil 24 and an outer copper foil electrode 25 . The inner copper foil 24 is placed inside the partial discharge current detector 11 , and the outer copper foil electrode 25 is placed outside the partial discharge current detector 11 .

The length of the inner copper foil 24 and the outer copper foil electrode 25 are equal, and the width is slightly smaller than the height of the coil skeleton 22 .

Both the partial discharge current detector 11 and the partial discharge voltage detector 12 are placed in an insulating casing 26 .

Both the bobbin 22 and the insulating case 26 have a gap of a certain width on one side, and the end of the insulating case 26 is connected with two BNC connectors 27 , which are respectively connected to the partial discharge current detector 11 and the lead-out end of the voltage detection unit 12 .

As shown in FIG. 3 , the signal filtering and amplifying unit 13 is mainly composed of an amplifying unit 31 , a low-pass filter 32 , a high-pass filter 33 and a shielding box 34 .

The signal filtering and amplifying unit 13 is mainly composed of high-speed operational amplifiers and resistors and capacitors, the amplification factor is not less than 20 times, the low-frequency cut-off frequency of the passband of the band-pass filter is not lower than 10 kHz, and is not higher than 100 kHz, and the high-frequency cut-off frequency is not low In 20MHz, not higher than 25MHz.

When the partial discharge sensor of this device is suspended on the overhead cable, according to Faraday's law of electromagnetic induction, it can be concluded that the output voltage of the partial discharge current detector 11 is the same polarity as the detected partial discharge current. The size of the capacitance parameter, the output voltage of the partial discharge voltage detector 12 has the same polarity as the detected partial discharge voltage, so as long as the reference direction of the partial discharge current detector 11 is known, the partial discharge can be deduced according to the transmission line wave process theory. direction of propagation.

An embodiment of the present utility model as shown in Figure 4, the electric current of the measured partial discharge signal and the polarity of the first pulse of voltage are the same, so the direction of propagation of the partial discharge signal is the same as the reference direction of the partial discharge current detector 11 same.

The above is only a specific embodiment of the utility model, but the technical characteristics of the utility model are not limited thereto, and any changes or modifications made by those skilled in the art within the scope of the utility model are all covered by the utility model. In the scope of the new patent.

Claims (9)

1. An overhead cable partial discharge charged detection sensor is characterized in that: it comprises a signal filter amplifier, a partial discharge current detector that is enclosed in a C-shaped cross section on the cable, and a partial discharge voltage detection device that is arranged on the partial discharge current detector. device. 2. A kind of overhead cable partial discharge electrified detection sensor as claimed in claim 1, is characterized in that: described partial discharge current detector comprises coil winding, bobbin and terminal impedance, and described coil winding is evenly wound on non-conductive by enameled wire. The magnetically permeable material coil frame, and the end of the coil winding passes through the center of the frame and is connected to the head end of the coil winding to form a return turn, and the end impedance of the coil winding is connected to the end. 3. A live detection sensor for partial discharge of overhead cables according to claim 2, characterized in that: said terminal impedance is a non-inductive resistor. 4. A kind of overhead cable partial discharge charging detection sensor as claimed in claim 2, is characterized in that: described partial discharge voltage detector comprises inner copper foil electrode and outer copper foil electrode, and inner copper foil electrode is arranged at partial discharge current Inside the detector, the outer copper foil electrodes are arranged outside the partial discharge current detector. 5 . The overhead cable partial discharge live detection sensor according to claim 4 , wherein the length of the inner copper foil electrode and the outer copper foil electrode are equal, and the width is smaller than the height of the coil frame. 6 . 6. A live detection sensor for partial discharge of overhead cables according to claim 2, characterized in that: both the partial discharge current detector and the partial discharge voltage detector are arranged in an insulating casing. 7. A partial discharge charged detection sensor for overhead cables as claimed in claim 6, characterized in that: the coil bobbin and one side of the insulating shell are provided with gaps for wires to penetrate, and the ends of the insulating shell are connected to two The BNC connectors are respectively connected to the terminals of the partial discharge current detector and the partial discharge voltage detector. 8. A partial discharge live detection sensor for overhead cables according to claim 1, wherein the signal filtering and amplifying unit comprises an amplifying unit, a low-pass filter, a high-pass filter and a shielding box. 9. A partial discharge charged detection sensor for overhead cables as claimed in claim 1, characterized in that: the amplification factor of the signal filtering and amplifying unit is not less than 20 times, and the passband low frequency cutoff frequency of the bandpass filter is not less than 10kHz, not higher than 100kHz, high frequency cut-off frequency not lower than 20MHz, not higher than 25MHz.