JPS6323733B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a photodetector equipped with a photoelectric conversion element that can detect a location where a flash fault has occurred in a gas insulation system based on light emitted during a flash fault.

FIG. 1 is a block diagram of a conventional photodetector. In FIG. 1, 1 is a photoelectric conversion element, 2 is a pulse signal generation circuit that generates a pulse signal depending on the magnitude of the output signal of the photoelectric conversion element 1, and 3
indicates a display device.

In such a photodetecting device, when light emitted during a flash fault enters the photoelectric conversion element 1, the photoelectric conversion element 1
is converted into an electrical signal corresponding to the luminescent phenomenon. Next, depending on the magnitude of the instantaneous value of the output signal, the pulse signal generating circuit 2 inputs a pulse signal to the display device 3 to display a flash fault.

On the other hand, FIG. 2 is a diagram showing a flash fault location where the conventional photodetector shown in FIG. 1 is attached to a gas-insulated busbar portion. In FIG. 2, 1a to 1c are the photoelectric conversion elements shown in FIG. 1, 2a to 2c are pulse signal generating circuits, and 3a to 3c are display devices. These photoelectric conversion elements 1a to 1c and pulse signal generation circuits 2a to 2c are each mounted in a metal box 4.
It is located inside. Each metal box 4 is connected to a gas insulated bus bar 11 via a connecting device 5.

A high voltage center conductor 6 is inserted into the center of the ground tank 7 of the gas insulated bus 11, and this high voltage center conductor 6 is supported by the ground tank 7 via a support insulating spacer 8. A space 9 made of compressed gas is formed between each supporting insulating spacer 8. Note that 10 indicates a flashing point.

Each of the photoelectric conversion elements 1a to 1c is installed in a flash section, and the photoelectric conversion elements 1a to 1c installed in each flash section are
The output waveform of the photoelectric conversion element 1b is shown in Figure 3A.
is shown. Further, the output waveform of the photoelectric conversion element 1a or 1c in which no flash flash occurred is shown in FIG. 3B.

In both FIGS. 3A and 3B, the horizontal axis represents time t, and the vertical axis represents output voltage v. In both figures, a represents high-frequency induced noise, and b in FIG. 3A represents the output waveform of the photoelectric conversion element.

By the way, in the conventional photodetecting device as described above, it is extremely difficult to completely eliminate the high frequency induced noise that occurs at the same time as a flash, and the magnitude of the instantaneous value of the output signal of the photoelectric conversion element causes a flash to occur. When indicating a fault, this output signal also contains high-frequency induced noise, and the sensitivity of the photodetector becomes very poor.

Furthermore, as shown in FIG. 3B, the high-frequency induced noise a also invades the photodetector where no flashover has occurred, so depending on the magnitude of the high-frequency induced noise,
There was a drawback that the display device malfunctioned.

This invention was made in order to eliminate the above-mentioned conventional drawbacks. By passing the output waveform of a photoelectric conversion element through an integrating circuit and a delay gate circuit, high-frequency induced noise generated at the time of flashing and the output signal due to light emission are eliminated. It is an object of the present invention to provide a photodetecting device that can completely remove high-frequency induced signals and accurately detect flashover points.

Embodiments of the photodetecting device of the present invention will be described below with reference to the drawings. FIG. 4 is a block diagram showing the configuration of one embodiment. In FIG. 4, the same parts as in FIG. 1 will be described with the same reference numerals. The output of the photoelectric conversion element 1 is sent to a detection circuit 20 that performs an integral action. The photoelectric conversion element 1 is housed in a shield box 27. shield box 27
is used to shield high frequency induced noise. The photoelectric conversion element 1, the detection circuit 20, and the shield box 27 constitute a detection section 24.

The output of the detection circuit 20 is sent to an integration circuit 21, and the output of this integration circuit 21 is sent to a delay gate signal generation circuit 22 and a gate circuit 23.
It is now being sent to The output signal Z of the gate circuit 23 is sent to the display device 3. Thus, the integration circuit 21, the delay gate signal generation circuit 22, and the gate circuit 23 constitute a delay gate circuit 25, and the delay gate circuit 25, the detection circuit 20, and the display device 3 constitute the photodetection device 26. It is configured. and,
This detection device 26 is housed in a shield box 27.

Next, the operation of the photodetecting device of the present invention configured as described above will be explained. When light emitted during a flash fault enters the photoelectric conversion element 1, an electric signal corresponding to the state of the light emitting phenomenon is converted into an output signal X having a predetermined time constant in the detection circuit 20. By further passing this output signal X through the integrating circuit 21, it is possible to sufficiently distinguish between the high frequency induced noise generated at the time of flashing and the output signal due to light emission.

The output signal Y of the integrating circuit 21 is sent to a delay gate signal generating circuit 22 and a gate circuit 23. Integration circuit 2 sent to delay gate signal generation circuit 22
1 output signal Y causes the delayed gate signal generation circuit 22 to generate a gate signal at time _t1 when the high frequency induced noise is sufficiently attenuated, and opens the gate of the gate circuit 23. By opening the gate of the gate circuit 23, the output signal Y of the integrating circuit 21 is transferred to the gate circuit 23.
is displayed on the display device 3 as the output signal Z of the gate circuit 23.

In this case, if the time t ₁ for generating the delay gate signal of the delay gate signal generation circuit 22 is set near the time until the output signal Y of the integrating circuit 21 reaches the maximum value, the output signal due to light emission can be It is inputted as an operating signal to the display device 3, and the flash fault is displayed without being affected by electrical noise at the time of a flash fault.

FIG. 5 shows an example in which the above-described photodetector of the present invention is applied to a gas insulation system. In FIG. 5, the same parts as in FIGS. 2 and 4 will be described with the same reference numerals. In FIG. 5, the gas insulated bus 11 is configured in the same manner as in FIG. A metal box 4 is connected via a device 5. The points up to this point are the same as those in FIG.

However, FIG. 5 differs from FIG. 2 in the following points. That is, each metal box 4 includes a photoelectric conversion element 1a.
~1c is stored. Photoelectric conversion elements 1a-1
c is the same as the photoelectric conversion element 1 in FIG. These photoelectric conversion elements 1a-1c are connected to photodetectors 26a-26c of the present invention via coaxial cables 40 for measurement, respectively. The photodetectors 26a to 26c are the photodetectors 2 shown in FIG.
It is the same as 6. These light detection devices 26a
26c are provided in the observation room 30.

The photodetectors 26a to 26c have the same configuration, but these photodetectors 26a
Regarding the detection section in ~26c, the light detection device 2
6a will be described in detail. FIG. 6A is a circuit diagram thereof, in which a capacitor C ₁ is connected in parallel with the photoelectric conversion device 1. One end of the photoelectric conversion element 1 is connected to one end of the inner conductor 40a of the coaxial cable 40, and the other end of the photoelectric conversion element 1 is connected to the other end of the outer conductor 40b of the coaxial cable 40.

A series circuit of a resistor R and a DC power source E in the detection circuit 20 is connected between the other ends of the inner conductor 40a and outer conductor 40b of the coaxial cable 40.
The other end of this internal conductor 40a is connected to an integrating circuit 21 shown in FIG. 4 via a capacitor _C2 . Note that a case is shown in which a photodiode is used as the photoelectric conversion element 1.

On the other hand, FIG. 6B is an equivalent circuit diagram of the detection section of FIG. 6A. 7A and 7B show the waveforms at each point of the photodetector of the present invention shown in FIG. 4. In the case of FIG. 7A, a flash fault occurs. FIG. 7B is a diagram showing an example of the waveforms of the output signal X of the detection circuit 20 and the output signal Y of the integration circuit 21 in the interval in which no flashover occurred.

Now, in FIG. 5, the gas insulated bus bar 11 is
When a flash fault occurs between the high voltage center conductor 1 and the grounding tank 7, and the photoelectric conversion element 1a housed in the metal box 4 detects the flash fault, the electrical signal is sent to the photodetector through the coaxial cable 40. 26a, but in the equivalent circuit _of the detection section shown in _FIG . The output waveform is determined as follows. Then, the internal resistance of the photodiode decreases depending on the state of the light emission phenomenon at the time of flash, and the charge of the capacitance C ₀ is discharged in the closed circuit 100, and then the charge of the capacitance C ₀ is discharged. 200 is charged by the closed circuit 200.

Now, assuming that the discharging time constant is τ ₁ and the charging time constant is τ ₂ , the time constant τ ₂ is set so that the condition τ ₂ ≫ τ ₁ is satisfied.
If is determined by the capacitance C ₀ and the resistance R, a stable output signal can be obtained regardless of the state of the light emission phenomenon. Further, the actual output waveform at that time, that is, the output signal X of the detection circuit 20 is shown in FIG. 7A. _The waveform _of this output signal
Since it passes through the capacitor C ₂ , it becomes a waveform that does not include a DC component and crosses the zero point from positive to negative at time t ₁ as shown in FIG.

Next, a method of completely removing high-frequency induced noise from the waveform of the output signal X of the detection circuit 20 and operating the display device using only the output signal of light emission will be described in more detail with reference to FIG.

When the waveform of the output signal X from the detection circuit 20 described above is passed through the integration circuit 21, the high frequency induced noise component _a
It decays as a′ ₂ . Then, the output signal a ₁ due to the light emission becomes an output waveform such as a' ₁ (output waveform at point Y) that reaches its maximum value at time t ₁ (zero point) from flashing time t=0 (output waveform at point Y).

Assuming that the high frequency induced noise _a2 is sufficiently attenuated within the above time _t1 , the delay gate signal generation circuit 2
2, by generating a gate signal after time _t1 and opening the gate circuit 23, a waveform of the output signal Z of the gate circuit 23 without any high-frequency induced components can be obtained. When this output signal Z is used as an operating signal for the display device 3, the display device 3 operates only when the output signal Z is present to display a flash fault.

In the above embodiment, a photodiode is used as the photoelectric conversion element 1, but a phototransistor, a phototransistor,
A detection unit using a photo cell or the like may be used.

In addition, in the above embodiment, the photoelectric conversion element 1 is attached directly to the gas bus, but when detecting flash fault points in the gas bus or other parts, it is necessary to provide a peephole in each part. For example, it can be used as a portable photodetector, and the same effects as the above embodiments can be obtained.

As described above, according to the photodetection device of the present invention, the flash fault point is detected by the photoelectric conversion element, the signal converted to a predetermined time constant by the detection circuit is integrated by the integrator circuit, and the high-frequency induced noise component is integrated. The output signal caused by the flash is separated, and the output signal of this integrating circuit is delayed by a predetermined time in a delay gate signal generation circuit to generate a gate signal, attenuating high frequency induced noise, and using this gate signal to open the gate circuit. Since the output of the integrator circuit is sent to the display device, a stable output signal can be obtained regardless of the state of the light emission phenomenon at the time of flashing, and the high frequency induced noise generated at the time of flashing can be completely removed. This results in extremely high reliability.

[Brief explanation of the drawing]

Figure 1 is a block diagram of a conventional photodetector, Figure 2 is a block diagram of a conventional photodetector.
The figure shows a state in which a conventional photodetector is attached to a gas-insulated busbar, and Figure 3A shows the photoelectric conversion element in the flash section when a conventional photodetector is attached to a gas-insulated busbar. Output signal waveform diagram, 3rd
Figure B is a waveform diagram of the output signal of the above-mentioned photoelectric conversion element other than the flash section, Figure 4 is a block diagram showing an embodiment of the photodetector of the present invention, and Figure 5 is a diagram showing the photodetector of the present invention in the gas FIG. 6A is a circuit diagram showing the detailed configuration of the detection unit in the photodetection device of the present invention, and FIG. 6B is a diagram showing a state in which it is attached to an insulated bus bar.
6A is an equivalent circuit diagram of the detection section in FIG. 6A, FIG. 7A is a waveform diagram of the output signal of the photoelectric conversion element in the flash section of the gas insulated bus bar in FIG. FIG. 6 is a waveform diagram of an output signal of a photoelectric conversion element other than a flashover section on an insulated bus. 1, 1a to 1c...Photoelectric conversion element, 6...High voltage center conductor, 7...Grounding tank, 8...Insulating spacer for support, 9...Space, 10...Flash point, 1
1... gas insulated bus bar part, 20... detection circuit,
21...Integrator circuit, 22...Delay gate signal generation circuit, 23...Gate circuit, 25...Delay gate circuit, 26, 26a to 26c...Photodetector, 2
7...Shield box, 40...Coaxial cable. Note that the same reference numerals in the figures indicate the same or equivalent parts.

Claims (1)

[Scope of Claims] 1. A photoelectric conversion element that converts flash light of a gas insulation system into an electrical signal, a detection circuit that has an integral action that integrates the output signal of this photoelectric conversion element, and a detection circuit that integrates the integral value of this detection circuit. an integrator circuit that attenuates noise components by using an integrator circuit; a delay gate signal generation circuit that receives the output of this integrator circuit and generates a gate signal when the output signal reaches its maximum value; and a gate signal generated by the gate signal from this delay gate signal generation circuit. A photodetecting device comprising: a gate circuit for transmitting an output signal of the integrating circuit; and a display device for displaying a flash fault based on the signal output through the gate circuit. 2. The photodetecting device according to claim 1, wherein the photoelectric conversion element is housed in a shield box. 3. The photodetection device according to claim 1, wherein the detection circuit and the integration circuit are connected via a coaxial cable.