JP2015075482A - Partial discharge detection probe, portable partial discharge measurement device and measurement method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a portable partial discharge measurement device with high measurement sensitivity.SOLUTION: When a casing 1 is made of a non-conductive material, high frequency electromagnetic waves 4, 5 generated by partial discharge 3 propagate from an insulating material 2 of an electric/electronic device through the casing 1 to outside of an outer wall thereof. Partial discharge high frequency electromagnetic wave detection probes 6, 7 of a portable partial discharge meter 8 act as an antenna and allow the portable partial discharge meter 8 to receive the high frequency electromagnetic wave generated by the partial discharge and display a value corresponding to a measured value. The high frequency electromagnetic waves 4, 5 generated by partial discharge are directly detected from the outer wall or by approaching or being in contact with an insulating material 2 of an electric device regardless of whether a casing is made of a conductive or non-conductive material.

Description

The present invention detects weak high-frequency electromagnetic waves of partial discharge (including corona discharge), discovers the progress of insulation deterioration of electrical equipment at an early stage, predicts the time for repair and replacement of electrical / electronic equipment, and sudden failure To provide a portable partial discharge measuring instrument useful for preventing power failures and power outages.

Some electrical devices have deteriorated over time, and many of them are normally operated without being replaced even after the product lifetime recommended by the manufacturer is over.
Further, in recent years, the number of electrical facilities that cannot or cannot be inspected by a one-time / yearly power outage, which is normally performed, is increasing.
As a result, many electrical devices suddenly break down and break down, and in some cases, they develop into spillovers that lead to wide-area power outages, which can take a long time to recover.
In recent years, power supply has become tight, and such power outages and power distribution problems have a great social impact, so daily inspections by electrical chief engineers are becoming increasingly important.
Furthermore, if the progress of the deterioration of the insulator can be estimated, preventive maintenance can be performed, and a precise inspection time can be estimated and an electrical equipment repair plan can be drawn up. Therefore, there is a demand for a measuring instrument that can measure appropriate insulation deterioration.

For daily and periodic inspections, measurements are made using existing electrical equipment measuring instruments.
However, the current situation is that the partial discharge, which is the main cause of the insulation deterioration, cannot be measured on-site easily while electricity is being supplied (when the equipment is operating).

There are several types of partial discharge detection methods for electric devices in operation, but they are not highly sensitive and effective portable detectors. Generally, 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 during daily inspections and can detect partial discharges in a live state.

There are portable partial discharge detectors in part, but this is a method in which a sensor is brought into contact with a casing or a sound collecting microphone detects sound generated by partial discharge of an electric device housed in the casing. This method has low sensitivity, and at the detection stage, there are many cases where dielectric breakdown or large insulation deterioration is almost achieved.
In the noise measurement conducted by the chief electrical engineer in the field, cubicles and other air-conditioning equipment are often installed densely. It is very difficult to find an abnormal noise occurrence location in the equipment.
There is a demand for a measuring instrument that can easily identify a partial discharge location with high sensitivity.
(Hereinafter, the electrical / electronic device storage box is referred to as a casing)

Inspecting breakers, transformers, and power distribution equipment that are indispensable for electrical equipment, such as breakers, transformers, and power distribution equipment, must be opened to check for equipment malfunction. At this time, there is a demand for a measuring instrument that can easily determine whether or not partial discharge has occurred by contacting the outside of the panel to determine whether or not partial discharge has occurred.
In recent years, a lot of resin has been adopted as an insulator, and the exterior of breakers, PTs, CTs, lightning arresters and some other power distribution equipment is often made of resin. Is desired.

Conventionally, in order to investigate the deterioration of the transformer, the electricity is stopped, the insulating oil in the transformer is extracted, and the degree of deterioration is determined from the analysis of the decomposition gas of the insulating oil based on the partial discharge.
For this reason, the number of days is also required for the analysis, which not only requires a large amount of work and time, but also does not necessarily make an effective determination of insulation deterioration. There is a need for a measuring instrument that can more easily diagnose deterioration without stopping 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.
There is a demand for a measuring instrument that can detect the difficult partial discharge phenomenon, which is very difficult to grasp the insulation deterioration in the metal pipe of GIS.

In view of the above-mentioned background art, in the conventional partial discharge measurement, the charge amount is measured by integrating the high frequency discharge current with the capacitor, so that the measurement sensitivity is lowered by the disappearance of the important frequency characteristics. Because of problems such as power supply noise, it is difficult to make measurements on-site.
In the case of contacting the outer wall of the casing with high frequency electromagnetic waves generated from partial discharge, regardless of conductivity or non-conductivity, or in the case of insulators (cables, PT, CT, etc.) of electrical equipment, Provided is a portable partial discharge measuring device that detects partial discharge by contact.

Since the present invention has a higher sensitivity than the conventional partial discharge measuring device, the remaining life of the insulator can be estimated from the progress of the partial discharge amount from the data obtained by periodic measurement, and the repair plan can be It will be possible to prevent sudden power outages.

As shown in FIG. 1, normally, when the casing 1 is made of a non-conductive material, the high frequency electromagnetic wave generated by the partial discharge: 3, 4 and 5 are from the insulator of the electric / electronic device: 2. Propagated out of its outer wall via casing 1.
Portable partial discharge measuring device: The partial discharge high frequency electromagnetic wave detection probe (6: A, 7: B) equipped in 8 performs the antenna function, and the portable partial discharge measuring device: 8 receives and corresponds to the measured value. The value to be displayed.

As shown in FIG. 2, when the casing 1 is made of a conductive material, high-frequency electromagnetic waves generated by the partial discharge reach the casing, but are not propagated from the outer wall to the external space. However, a high frequency electromagnetic field due to a high frequency electromagnetic wave exists in the conductive casing. This electromagnetic field exists regardless of the presence or absence of paint on the outer wall of the casing. This high frequency electromagnetic field is detected by a partial discharge high frequency electromagnetic wave detection probe (6: A, 7: B).

FIG. 3 shows that the probe (6: A, 7: b) is isolated from the viewpoint of safety when the probe (6: A, 7: b) is brought close to the vicinity of the insulator of the electrical equipment (non-contact / contact) in order to identify the occurrence of partial discharge. The metal plate piece: 9 and the ground wire necessary for grounding: 10 and the ground bus bar: 11 are shown. Alternatively, the insulating plate 9 having sufficient dielectric strength can be used. In this case, the ground line: 10 is not necessary.
The partial discharge high-frequency electromagnetic wave measurement method in this case conforms to the above [0011] and [0012].

The portable partial discharge measuring instrument is configured to require a detailed inspection when a signal level (threshold value) exceeding a predetermined level is exceeded, and can be detected by the above [0011] to [0013]. If the measured signal level exceeds the threshold value, the measured waveform is stored in the memory and analyzed with a separate oscilloscope, or it must be a partial discharge that requires final precision inspection on-site with a portable oscilloscope. Is identified.

Electrical equipment that needs early detection of partial discharge phenomena includes receiving and transforming equipment (transformers, switches, circuit breakers, PT, CT and other ancillary equipment), covered wires / cables, generators, and motors. There are lightning arresters for direct lightning protection, and electronic devices.
The present invention can detect a partial discharge that occurs at an insulation failure point in an electric / electronic device regardless of whether the supply voltage is high or low.

In this partial discharge measurement method, the first stage is a simple diagnosis of the presence or absence of insulation deterioration due to partial discharge at the site of electrical equipment, the second stage is the identification of the location where partial discharge occurs, and the third stage This means that only limited electrical equipment that exceeds the threshold can be finely inspected, and not only can the number of precision inspections be greatly reduced, but also the cost reduction due to the precision inspection of all of the conventional periodic major electrical equipment, and the time required for periodic precision inspections. Restrictions are greatly relaxed. Furthermore, it is possible to grasp the progress of the insulator deterioration.

Shows the detection method of the partial discharge high frequency electromagnetic wave from the outer wall of the non-conductive casing of electrical and electronic equipment. Shows the detection method of partial discharge high frequency electromagnetic wave when it is composed of conductive casing of electric / electronic equipment Shows the detection method when it is necessary to bring the probe for partial discharge high frequency electromagnetic wave detection close to or in contact with the insulator of electrical / electronic equipment.

1 Electrical and electronic equipment casing (Material: conductive / non-conductive material included)
2 Insulator of electrical / electronic equipment 3 Partial discharge source 4 High frequency electromagnetic wave due to partial discharge: Electric field 5 High frequency electromagnetic wave due to partial discharge: Magnetic field 6 Probe terminal for detecting partial discharge high frequency electromagnetic wave: A
7 Probe terminal for partial discharge high frequency electromagnetic wave detection: B
8 Portable partial discharge measuring device (High-frequency electromagnetic wave receiving circuit and display circuit)
9 Metal plate for safety protection or sufficient dielectric strength when detecting probe (6: A, 7: B) is close to measure high frequency electromagnetic waves without electrical equipment being protected by casing Insulated plate 10 Ground wire 11 for safety protection Grounding bus of structure

Claims (5)

Partial discharge is a phenomenon that indicates the state of deterioration of insulators in electrical equipment, and generation of high-frequency electromagnetic waves is observed along with this. From the magnitude of this electromagnetic wave, the deterioration state of the insulator can be known.
A portable partial discharge measuring device that can detect high-frequency electromagnetic waves themselves due to partial discharges generated from insulators in electrical equipment.
A portable partial discharge meter that quantitatively displays the strength of the high-frequency electromagnetic field input from the probe. When the electrical equipment is surrounded by a casing made of a non-conductive material, a portable partial discharge measuring device that detects high-frequency electromagnetic fields from the wall surface with a probe by contacting the outer wall surface. When the electrical equipment is surrounded by a casing made of a conductive material, etc., a portable partial discharge measuring device by detecting a high frequency electromagnetic field from the wall surface with a probe by contacting the outer wall surface. Grounding a conductive protective plate with a grounding wire to ensure safety when the probe of a portable partial discharge measuring instrument is brought close to or in contact with the insulation of an electrical facility to identify the location of the partial discharge; Or a portable partial discharge measuring instrument that measures high-frequency electromagnetic waves by using an insulating plate with sufficient dielectric strength. Method for detecting and identifying high-frequency electromagnetic waves due to partial discharges First stage: High-frequency electromagnetic waves are detected as partial discharges with a portable partial discharge measuring device, but the high-frequency electromagnetic wave measurement band includes noise other than partial discharges. Measure the presence or absence of partial discharge including the possibility (confirmation of the occurrence of partial discharge)
Second stage: If the measured high-frequency electromagnetic wave is detected even at a low level, the direction / location where the detection level becomes a large value is specified. (Specific location of partial discharge)
Third stage: If the measured partial discharge level is set to a threshold value based on data publicly disclosed that the risk of deterioration of the insulator is sufficient, an oscilloscope will be Use waveform analysis to identify partial discharge (identify partial discharge that may cause dielectric breakdown)
Portable partial discharge measuring instrument employing a three-stage measurement method

Images