JPH0283464A - Earth detector - Google Patents

Abstract

PURPOSE:To provide the title detector having high detection sensitivity and not affected by a temp. change by providing a high sensitivity pressure sensor in the hermetically sealed container communicating with the pressure container of gas insulated machinery and allowing the hermetically sealed container to the pressure container through a small hole. CONSTITUTION:A hermetically sealed container 40 is allowed to communicate with the pressure container 11 of gas insulated machinery through piping 13 and a high sensitivity pressure sensor 32 is provided in the hermetically sealed container 40 through an insulating joint 31 so as to be insulated from the hermetically sealed container 4. The gas pressure in the hermetically sealed container 40 is always held so as to be same to that in the pressure container 11 by a fine vent hole 50. Pressure balance is held against a gentle change such as a temp. change but the shock pressure wave of gas generated at the time of earth is detected as difference pressure by the pressure sensor 32. The power supply of the pressure sensor 32 is supplied through an insulated transformer 35 and an AC/DC power supply and the output thereof is converted to a light signal by an electro-optical converter 37 to be outputted through an optical cable 39.

Description

DETAILED DESCRIPTION OF THE INVENTION [Object of the Invention] (Field of Industrial Application) The present invention relates to a ground fault detector for gas insulated equipment.

(Prior Art) When a ground fault occurs in gas-insulated equipment, an impact pressure wave is generated inside a pressure vessel (grounded metal vessel) due to the energy of the ground fault arc, and propagates within the vessel.

As a means of detecting ground faults in gas insulated equipment,
A sealed case is provided that is connected to the outer cover of the switchgear via a communication pipe, and a detection switch such as a microswitch and a float that rises to the surface due to pressure rising waves in the event of a ground fault are provided inside this case. A device is known in which a detection switch is actuated by the floating action of the device to indicate a failure.

However, with this type of detector, as the amount of gas in the gas-insulated equipment that is communicated within the case increases, the peak value of the pressure increase due to a ground fault becomes smaller, so the detection sensitivity decreases. There is also the problem of malfunction due to increased pressure.

Points regarding this operation will be specifically explained using a conventional ground fault detector shown in FIG.

In Fig. 2, reference numeral 11 indicates a gas insulated device 12, which has a built-in high-voltage charging part in a jacket filled with insulating gas, is a switch case of a detector, and a switch case 11 and a connecting pipe 1 are provided at the bottom of the gas insulated device 12.
It has a gas introduction hole 14 connected through a cylinder 15 and a detection switch 1 such as a microswitch.
A cylinder 15 serving as a gas chamber 17 provided with a gas chamber 17 is installed vertically on the bottom surface of the switch case 12, and its lower opening side communicates with the gas introduction hole 14, and the upper part is connected to an end plate 18.
It communicates with the gas chamber 17 through a through hole 19 . End plate 18
The detection switch 16 is fixed to the extension part of.

Furthermore, a float 2 having a protrusion 21 is provided inside the cylinder 15.
0 is movably provided.

In such a detector, when operating gas insulated equipment,
In the gas chamber 17 of the switch case 12, the insulating gas from the switchgear 11 is connected to the communication pipe 13, the gas introduction hole 14, and the cylinder 1.
5 and maintained at a constant pressure. Now, when a ground fault occurs in the switchgear 11, the internal pressure of its jacket increases, and the float 20 floats due to the differential pressure between the pressure transmitted to the cylinder 15 and the pressure inside the gas chamber 17 of the switch case. Then, the detection switch 16 is activated via the protrusion 21. The detection switch 16 opens and closes a detection circuit (not shown) to indicate a failure.

(Problem to be Solved by the Invention) However, in such a configuration, when the gas amount in the gas insulated equipment 11 increases or when the ground fault current is small, the pressure wave rise value becomes small and the detection Sensitivity is an issue. In particular, the pressure rise value due to ground fault current and other factors (e.g.
If there is almost no difference from the pressure rise value due to temperature fluctuations, the detector may malfunction.

This invention has been developed in view of the above-mentioned points of the present invention, and is capable of grounding gas-insulated equipment that is small, lightweight, low-lying, and highly sensitive, and does not malfunction due to pressure increases caused by factors other than ground faults. The present invention provides a fault detector.

[Structure of the invention]

(Means for solving the 1m problem) A ground fault detector for gas insulated equipment according to the present invention includes a highly sensitive pressure sensor insulated from the sealed container that communicates with the pressure vessel of the gas insulated equipment. , and the pressure inside the sealed container is communicated with the pressure container through a minute ventilation hole so that the static pressure becomes the same, and the power source of the pressure sensor is connected to the pressure sensor by an isolation transformer. After insulating from the sealed container and converting the output of the pressure sensor into an optical signal.

transmitted to the receiving side.

(Function) With this configuration, detection sensitivity is improved and the pressure waveform itself can be detected.

This software is also designed to prevent malfunctions of the detector due to small and gradual pressure fluctuations caused by temperature rises, etc.

(Example) Embodiments of the present invention will be described below with reference to the drawings.

FIG. 1 shows an embodiment of the present invention.

A sealed container 40 is connected via a pipe 13 to a pressure container 11 of gas insulated equipment.

A highly sensitive pressure sensor 32 is provided in the sealed container 40 and insulated from the sealed container 40 via an insulating joint 31 .

The gas pressure of gas insulated equipment is usually 3 to 5 kg/al. On the other hand, the peak value of the pressure wave that occurs during a ground fault is
If it is small, it will only be about 0.03kg7a#.

Since the pressure sensor 32 is configured to accurately capture such minute pressure waves, the minute ventilation hole 50, which cannot directly apply the gas pressure of the gas insulated equipment to the pressure sensor 32, This ventilation hole 50 is intended to avoid such problems.

The gas pressures in the sealed container 40 and the pressure container 11 are always kept the same. The ventilation hole 50 is made to be a minute hole of 0.01 m or less to prevent temperature fluctuations and the like. It is sufficient to equalize the pressure in the sealed vessel 40 and the pressure vessel 11 against slight pressure fluctuations, but it is sufficient to equalize the pressure in the sealed vessel 40 and the pressure vessel 11. However, it is sufficient to equalize the pressure in the sealed vessel 40 and the pressure vessel 11. However, it is sufficient to equalize the pressure in the sealed vessel 40 and the pressure vessel 11. However, it is sufficient to equalize the pressure in the sealed vessel 40 and the pressure vessel 11. Since it takes time for the pressure to reach the same level, a pressure sensor can detect the pressure wave as a differential pressure.

In FIG. 1, the pressure sensor 32 is insulated from the gas insulated equipment body and the sealed container 40 via an insulated joint 31, and as the power source for the pressure sensor 32, an AC power source is connected via an airtight terminal 33 to the sealed container. drawn into the container 40,
Then, after noise and surge countermeasures are taken using the isolation transformer 35 at the container inlet, AC/DCfl! source 36.

Further, the output of the pressure sensor 32 is converted into an optical signal by an electro-optical converter 37, and then transmitted to the receiver side via an optical cable 39 via an airtight terminal 34.

With such a configuration, the influence of high frequency surges generated by the gas insulated equipment body can be excluded, and the reliability of the detector can be increased.

Since the pressure sensor 32 is highly sensitive and outputs electrical signals proportional to pressure, it is possible to easily exclude the above-mentioned gradual pressure rise etc. through software processing based on these signals. .

〔Effect of the invention〕

Because it can detect ground faults with high sensitivity and eliminate malfunctions,
Improved performance and reliability of ground fault detectors can be obtained.

[Brief explanation of the drawing]

FIG. 1 is a sectional view of a ground fault detector showing an embodiment of the present invention;
FIG. 2 is a sectional view showing a conventional ground fault detector. 11... Gas insulated equipment 12... Switch case 13... Communication pipe 14... Gas introduction hole 15... Cylinder 16... Detection switch 17... Gas chamber 18... End plate 19 ...Through hole 20...Float 2
1... Protrusion 31... Insulating joint 32
...Pressure sensor 33, 34...Airtight terminal 35...Isolation transformer 36...AC/D
C power supply 37...Lightning converter 38...AC
Power line 39... Optical cable 40... Sealed container 50... Vent agent Patent attorney Nori Chika Ken Yudo Ken Daishimaru Figure 1 Figure 2

Claims (2)

[Claims] (1) A pressure sensor that converts pressure into an electrical signal is electrically insulated and stored in a sealed container that communicates with a grounded metal container of a gas-insulated device that stores a high-voltage charging part together with an insulating gas, and The pressure inside this sealed container is always maintained at the same pressure as that of the pressure container through a minute ventilation hole, and the output cable of the pressure sensor and the power cable are connected through airtight terminals provided in the sealed container. A ground fault detection device for gas insulated equipment, characterized in that it is connected to (2) A claim characterized in that a DC power source is provided insulated from the outside in the sealed container housing the pressure sensor, and an electrical/optical conversion unit is provided for converting the output of the pressure sensor into an optical signal. 1. A ground fault detection device for gas insulated equipment according to item 1.