JP2013113837A - Sensor for detecting corona discharge, portable measuring device, and measuring method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method for detecting a high-frequency current generated from corona discharge with high sensitivity, irrelevant to the material of a casing.SOLUTION: In the case that a casing 1 for an electrical or electronic apparatus has insulation properties, probe terminals 9 and 10 of a corona discharge detector 12 are closely contacted with a protective insulation plate 16 for electrical shock prevention so as to detect a corona discharge current flowing through a capacitance between the casing 1 and the protective insulation plate 16 for electrical shock prevention. In the case that a casing 1 for an electrical or electronic apparatus is formed of metal, the probe terminals 9 and 10 of the corona discharge detector 12 are closely contacted with an external wall of the casing.

Description

The present invention detects a weak current of corona discharge, detects insulation deterioration of electrical equipment at an early stage, predicts repair / replacement time of electrical / electronic equipment, and prevents coronary discharge detection and power failure. Provide a bowl.

Some electrical devices have deteriorated over time, and some have been operated without being replaced even after the product lifetime has passed.
As a result, many electrical devices suddenly break down and break down, and in some cases, they develop into spillovers, leading to wide-area power outages, which can take a long time to recover.
In recent years, power supply is tight, and such power outages and problems with dispatched power have a great social impact, so daily inspections of electrical equipment engineers are becoming increasingly important.

For daily and periodic inspections, measurements are made using existing electrical equipment measuring instruments.
However, the current situation is that it is not possible to measure the deterioration of corona discharge easily and while electricity is being supplied (during operation of the equipment).

There are several methods for detecting corona discharge in electrical equipment in operation, but none are portable detectors. In general, most inspection equipment is installed in factories or the like for continuous monitoring of important equipment. Therefore, it is desired that it can be carried at the time of daily inspection and can detect discharge in a live state.

There is a portable corona discharge detector in part, but it is a method of detecting a change in the discharge voltage of an electric device housed in the casing by contacting the sensor with the casing.
Originally, there is a demand for a measuring device that can find a corona discharge occurrence location so that an abnormal noise occurrence location can be found from an unspecified number of devices in noise measurement performed by equipment inspection engineers. (Hereinafter, the electrical / electronic device storage box is referred to as a casing)

Inspecting circuit breakers and lightning arresters installed in power boards and distribution boards, which are indispensable for electrical equipment, must open the doors of the boards and investigate whether there are any malfunctions.
At this time, there is a demand for a sensor that can determine whether corona discharge has occurred from the outside of the panel by approaching or contacting it.
By the way, since the exterior of the breaker and lightning arrester is made of resin, a measuring instrument with a sensor that can detect the phenomenon of discharge from here is desired.

In the inspection of the power supply panel, whether or not the lightning arrester is normal is measured by checking whether there is any leakage current in the ground wire. However, since lightning arresters and zinc oxide type to gap type are also mixed in recent years, it is desirable to add not only leakage detection but also whether or not corona discharge has occurred to failure determination.

In order to investigate the deterioration of the transformer, electricity is turned off, the oil in the transformer is extracted, the components are analyzed, and the degree of deterioration is judged. There is a need for a measuring instrument that can more easily diagnose deterioration without turning off electricity. The same demand exists for OF cables.

A large number of power cables are laid in a pit or the like, and it is very difficult to specify from where the discharge phenomenon occurs in the power cable.
A measuring instrument that can detect the difficult initial discharge phenomenon is desired.

In view of the above-mentioned background art, in the conventional corona discharge measurement, because the charge amount is measured by integrating the corona discharge current with a capacitor, the measurement sensitivity is lowered by the disappearance of an important frequency characteristic, There are many restrictions such as power supply noise, making it difficult to measure locally. The present invention provides a measurement method for detecting high-frequency current generated from corona discharge with high sensitivity regardless of the material of the casing.

Since the present invention is a sensor having a higher sensitivity than before, it is a measuring instrument that can identify an electrical device having an initial corona discharge deterioration from a number of devices.
As a result, the deterioration of the insulation progresses due to the corona discharge, and a sudden power failure can be prevented in advance.

In the case where the casing is not made of an insulating material or has no casing, in FIG. 1, the corona discharge current: 6 indicates that the high frequency current of 10 to 40 MHz emitted from the corona discharge point: 3 is the corona discharge point: 3 Casing: Capacitor composed of the inner surface of the casing: 4, Capacitor of the casing itself: 7, Casing: The outer wall of the casing 1 and a protective insulating plate for preventing electric shock (also serving as an adapter; hereinafter referred to as adapter): Capacitor configured between 16 : 14, adapter impedance: via Zf, probe of corona discharge detector: 9 is received and passes through the detector, probe: 10, adapter impedance Zf, capacitor: 15 → 8 → 5 Corona discharge occurrence point: Return to the supply point of 3 corona discharge energy.
When the casing is made of metal In the case of FIG. 2, since the casing is made of a metal material such as steel, the corona discharge current is detected from the outer surface of the casing, since electric lines of force are not released into the atmosphere. The probes 9 and 10 of the detector must be in direct contact with the casing, and the current route to the corona discharge detector of corona discharge current: 6 is the corona discharge point: 3 → 4 → 7 (impedance including casing coating). : Z) → Probe: Received at 9 → Probe: 10 → 8 → 5 → Corona discharge generation point: Return to 3 energy supply point Even in this case, detection is possible using an adapter. This can be achieved by closely contacting the outer wall.
The configuration is the same as the state without the capacitors 14 and 15 in FIG.

コロナ放電を検知出来る。
感電防止用保護絶縁版：１６は、検出のためのアダプターとしての機能も有し、センサーとセットとして被検出体に近づけることによる電界分布を変えることなく測定できる機能を有している。
コロナ放電検出対象電気・電子機器装置の外形構造に則したアダプターを構成することで検出の確度を保障できる。Electrical equipment that needs to detect the discharge phenomenon at an early stage includes receiving / transforming equipment, covered wires / cables, generators, motors, lightning arresters for direct lightning protection, and other electronic devices.

Corona discharge can be detected.
The protective insulating plate 16 for preventing electric shock also has a function as an adapter for detection, and has a function capable of measuring without changing the electric field distribution by being brought close to the detection object as a set with the sensor.
The accuracy of detection can be assured by configuring an adapter that conforms to the external structure of the electrical / electronic device device subject to corona discharge detection.

Illustration when the electrical / electronic equipment casing is an insulator The method for detecting the corona discharge current when the electrical / electronic equipment casing is made of an insulator such as vinyl chloride is shown. The protective insulating plate for preventing electric shock also serves as an adapter for detection. FIG. 2 shows a method for detecting the corona discharge current when the casing is made of a metal material such as steel.

1 Electrical / electronic equipment casing 2 Electrical / electronic equipment body 3 Corona discharge source 4 Capacitance between the corona discharge source and the casing (external stray capacitance)
5Capacitance between corona discharge source and casing (external stray capacitance)
6 corona discharge current: I
7 Impedance of casing Fig. 1: Capacitor in the case of insulating casing Fig. 2: Impedance of casing 8 in the case of metal casing Fig. 1: Capacitor in the case of insulating casing Fig. 2: In the case of metallic casing , Impedance 9 Corona discharge current detector probe terminal: A
Probe terminal of 10 corona discharge current detector: B
11 Corona discharge current detection coil 12 Corona discharge detector 13 Corona discharge current receiving circuit and display circuit 14 Capacitance between casing for electrical / electronic device and protective insulating plate for preventing electric shock 15 Casing for electrical / electronic device and for preventing electric shock Capacitance between protective insulating plates 16 Protective insulating plate for preventing electric shock: Impedance Zf, which also serves as an adapter for detecting corona discharge current.

Claims (2)

Measuring circuit method that can detect changes in minute high-frequency current due to corona discharge or partial discharge (hereinafter referred to as corona discharge) of electrical equipment and external high-frequency capacitance using minute high-frequency current due to corona discharge generated inside the test specimen High sensitivity sensor circuit. A portable measuring instrument that can detect changes in the discharge current in the atmosphere with the above sensor and detect the source of discharge from an unspecified number of electrical devices.
A portable measuring instrument that has an A / D converter that converts an analog signal input from a sensor into a digital signal, and that can display the intensity of the discharge current in multiple stages on the display.

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