JPS62214365A - Switch - Google Patents

Abstract

PURPOSE:To detect a displacement current from an electrostatic charging part and to easily detect a ground fault accident in a power distribution line system by arranging a detection electrode in a shield container and arranging it opposite the electrostatic charging part. CONSTITUTION:A window hole 5 is formed in the top surface of the shield container 1 which is made of a conductive member and grounded and the plate type detection electrode 10 which is supported by a rod type support member 6 having a rib part made of an insulating material is arranged in the container 1. The top surface of the electrode 10 is arranged closing the window hole 5 across a gap opposite the internal surface of the container 1. Further, the signal processing circuit composed of an amplifier circuit and a BPF is connected to the electrode 10 to constitute the voltage sensor. The window hole 5 is arranged opposite an electrostatic charging part such as a bushing internal conductor rod or cable connection terminal which is exposed to the outside. The frame, case, etc., of a switch are grounded to constitute a grounding part, but there is neither the mutual position shift between the grounding part and electrostatic charging part nor variation in the distance among respective phase electrostatic charging parts, so there is no relative positive shift between the detection electrode and grounding part of the sensor and a displacement current is easily detected.

Description

DETAILED DESCRIPTION OF THE INVENTION Object of the Invention (Field of Industrial Application) This invention relates to a switch equipped with a voltage sensor.

(Prior Art) As a conventional method for detecting alternating current voltage, a potential transformer (hereinafter referred to as PT) or a capacitor-divided voltage transformer (hereinafter referred to as PD) is generally used at commercial frequencies. In addition, in recent years, methods other than PT that apply optoelectronic technology have been proposed. The optoelectronic technology is called a measurement lunar transformer (hereinafter referred to as optical PT), and many of them are being researched.

This light PT is obtained by placing an element having the Pockels effect in an electric field and making linearly polarized light incident on it in the same direction as the electric field.
The refractive index for the orthogonal two components shows different changes depending on the electric field strength, and the propagation speed also differs, as a result,
This method takes advantage of the fact that a phase difference occurs between two orthogonal components of light, and the emitted light becomes elliptically polarized light.

In addition, for high-potential charged parts such as power transmission lines, connect a capacitor for voltage division or a light emitting element in series with the capacitance formed by the space for insulation of the charged part. A type of electroscope that detects the presence or absence of electrostatic charge is known.

(Problems to be Solved by the Invention) The conventional PT or PD as described above is a contact type in which it is attached directly to a charged part of a cable, etc. for power distribution lines, and therefore it is necessary to consider insulation. Not only that, PT, P
In D, coil, iron core.

Since a condenser or the like is used, there is a problem that the whole device becomes large and heavy, and therefore, there is a problem that the installation work is time-consuming.

In addition, optical PT is a non-contact method, and although it has excellent insulation properties, it requires a laser oscillator or the like to obtain linearly polarized light, and there is a problem that the entire device is expensive.

Furthermore, in the case of a voltage detector type, the input impedance of the amplifier circuit for amplifying the signal detected through the capacitance formed by the space is generally set to be high.

For this reason, changes in leakage resistance due to supports and structural materials directly connected to the input terminal of the amplifier circuit will affect the effective input impedance of the amplifier circuit, especially if the sensor is installed outdoors or outside the device. The exact instantaneous value of the potential of 1q
It was difficult to do so.

To solve this problem, simply reducing the input impedance would result in a decrease in the output voltage, making stable and accurate voltage detection impossible, especially for power distribution systems where the potential of charged parts is low.

Due to the above situation, the non-contact voltage detector type described above also detects the analog waveform of the potential of the charged part as its instantaneous value.

It has not yet been possible to accurately detect and measure each phase, including phase differences, to process the output, and to use the results in power distribution technology such as system accident protection.

Therefore, in order to solve the above-mentioned problems, this invention provides a voltage detection method that utilizes a displacement current flowing from a charged part through a space capacitance, with particular consideration for use in a power distribution line system. It is an object of the present invention to provide a switch equipped with a non-contact voltage sensor that also takes into account its effective detection arrangement.

Structure of the Invention (Means for Solving Problems) This invention has a transparent window hole in the upper surface of an electrically grounded shield container made of a conductive member, and an insulating material connected to the container. A plate-shaped detection electrode supported by a rod-shaped support member having folds is disposed, and the window hole is closed on the upper surface of the detection electrode with a gap between it and the inner surface of the container. In addition, a signal processing circuit consisting of an amplifier circuit and a bandpass filter is connected to the detection electrode to constitute a voltage sensor, and the voltage sensor The windows are arranged facing each other.

(Function) In a switch, the machine frame, case, etc. of the switch are grounded and constitute a grounding part, but the mutual position of the grounding part and a charged part such as a conductor rod inserted through the bushing and the charged part of each phase are important. Since there is no change in the distance between the two, the relative position between the detection electrode of the voltage sensor and the grounding part closest to the detection electrode does not change, and the displacement current from the charged part can be accurately detected. .

(Example) Hereinafter, an example in which the present invention is embodied in an exposed type closure will be described with reference to FIGS. 1 to 7.

The frame 32 of the switch As, which is attached to the arm of the telephone pole (not shown) via the support fitting 31, has a main body insulator 3 for each phase.
3 is supported and fixed downward.

The frame body 32 includes an upper frame 32a and two support rods 3 disposed at a predetermined distance from each other with respect to the upper frame 32a.
4, and a pair of sliding guide rods 35 connected between the upper and lower frames 32a and 32b between the support rods 34, and are grounded.

A fixed electrode 37 is fixed to the inner top of the main body insulator 33 via a fitting 36, and a connecting terminal 38 supported by the fitting 36 is connected to the base end of the fixed electrode 37. The lower end of the connection terminal 38 extends downward,
It protrudes outward from a side portion of the main insulator 33 that protrudes laterally. The connection terminal 38 is fastened to the lower side surface of the main body insulator 33 by a bolt 38a. A base end portion of a terminal cover 39 made of insulating synthetic resin is fitted onto the outer periphery of the side portion of the main body insulator 33 corresponding to the connection terminal 38, and the terminal cover 39 covers the distribution cable end of the connection terminal 38. It is arranged so as to cover the connecting portion 38b to be connected.

An elevating frame 40 is fitted into the sliding guide rod 35 so as to be slidable in the vertical direction, and a movable insulator 41 corresponding to the main body insulator 33 is fixed upward to the upper surface of the elevating frame 40. A movable contact blade 42 is provided on the upper part of the movable insulator 41, and the movable contact blades 42 are formed so that both ends thereof can be inserted into the fixed electrodes 37 on the power supply side and the load side in the main body insulator 33, respectively.

An opening/closing operation mechanism 43 is linked to the lower part of the lifting frame 40, and by opening and closing an operating handle 44, the lifting frame 40 can be driven up and down via the opening/closing operation mechanism 43.

Each phase voltage sensor SLJ, 3v, 3w is spaced apart from the connection terminal 38 of each phase in the direction directly above the upper frame 3.
2, it is suspended and supported from the side portion of the power supply side via a hanging metal fitting 45. In addition, each voltage sensor 3u, 3v,
Since the three WLs have the same configuration, the voltage sensor 3u will be explained.

This voltage sensor 3u is composed of a detection section 7 and a signal processing circuit 8.

To explain the detection unit 7, a base 2 made of a conductive material such as stainless steel and a lid case 3 are fastened and fixed with screws 4 to constitute a shield container 1.
A rectangular window hole 5 is provided in the upper surface, that is, the upper surface of the lid case 3.

The central lower surface of the shield container 1, that is, the inner surface of the base 2, is made of an insulating material such as synthetic resin, and has a plurality of folds a.
, b, c on the outer periphery of the round bar-shaped support member 6 with screws 4.
' (two are used in this embodiment), and the lid case 3 is fixed to the upper end of the support member 6.
A flat detection electrode 10 is arranged parallel to the upper surface and closes the window hole 5 from the inside through a gap.
It is fixed at 11.

Note that the detection electrode 10 is made of metal or conductive resin.

It is made of a conductive member such as conductive rubber, and stainless steel is used in this embodiment.

A single-core shielded electric wire 31 introduced from the outside of the shield container 1 through the packing P is inserted into the detection electrode 10 through the T-shaped insertion hole 6a provided in the support member 6. It is connected. Further, the shield braided wire 31b of the single-core shielded electric wire 31 is connected to the base 2,
The shield container 1 is grounded via the shield braided wire 31b.

This single-core shielded electric wire 31 is introduced into a case (not shown) of a zero-phase voltage detector 20 to be described later, and the core wire 3
1a is connected to a signal processing circuit 8 included in the zero-phase voltage detector 20.

This signal processing circuit 8 includes each voltage sensor Su, Sv.

Since it has the same configuration as 3w, the signal processing circuit 8 connected to the detection electrode 1o will be explained.

The signal processing circuit 8 is roughly divided into an amplifier circuit A and a bandpass filter circuit B.

When the displacement current from the detection electrode 10 is input, the amplifier circuit A amplifies the displacement current and outputs a waveform similar to the displacement current. Specifically, it is configured as follows. . That is, the input terminal P of the signal processing circuit 8
1 is connected to the grounding wire E1 via a resistor R1, and the case 1 and lid 3 forming the shield electrode are connected to the grounding wire E1 via the terminal P2. 3 is connected to the ground line E1 via the terminal P2. Between both terminals of the resistor R1, a pair of diodes D1. The parallel circuit of D2 is connected,
This serves as a protection circuit to prevent excessive input from the detection electrode 10.

The input terminal P1 is connected to the operational amplifier OP1 via a resistor R2.
is connected to the inverting input terminal of the operational amplifier O.
The non-inverting input terminal of P1 is connected to the ground line E1 via a resistor R3. A parallel circuit of a capacitor C1 and a resistor R4 is connected between the inverting input terminal and the output terminal of the 8-7 amplifier OP1. In addition, capacitors C2 and C3
is for stabilizing the power supply of the operational amplifier OPI.

When a signal similar to the displacement current is applied from the amplification circuit A, the bandpass filter B is set to selectively amplify and extract the frequency with a center frequency of 60Hz or 50Hz based on the signal. Basically, it is structured as follows. That is, operational amplifier OP1
A series circuit of a capacitor C6 and a resistor R5 is connected between the output terminal of the operational amplifier OP2 and the inverting input terminal of the operational amplifier OP2, and the non-inverting input terminal of the operational amplifier OP2 is connected to the ground line E1 via the resistor R6. There is. A parallel circuit consisting of a series circuit of capacitors C4 and C5 and a series circuit of resistors R7 and R8 is connected between the inverting input terminal and the output terminal of the operational amplifier OP2.

Further, a capacitor C7 is connected between a point a between the resistors R7 and R8 and the ground line E1. Operational amplifier OP2
A resistor R9 is connected between the output terminal of the signal processing circuit 8 and the output terminal pu of the signal processing circuit 8.

A bandpass filter B is constituted by the resistors R5 to R9, the capacitors C4 to C7, and the operational amplifier OP2. The detection electrode 10° and the signal processing circuit 8 constitute a voltage sensor Su. Note that the output terminals of the other voltage sensors sv and sw are expressed as Pv and Pw instead of pu for convenience of explanation.

The voltage sensors 3u, 3v, and Svv of each phase are connected to a zero-phase voltage detector 20 attached to the utility pole, and a detection circuit 21 built in the zero-phase voltage detector 20 is connected to an adding circuit 22. , the same addition circuit 22. It is composed of an N source circuit 23 for the navigation N pressure sensor.

The adding circuit 22 connects each voltage sensor Su, Sv.

The signals outputted from Sw and selected at a predetermined frequency are synthesized and a zero-phase voltage VO signal is output to the output terminal P thereof. Specifically, the adder circuit 22 is configured as follows.

That is, the output terminals Pu, P of the voltage sensors su, sv, Sw are connected to the G point of the inverting input terminal of the operational amplifier OP3 via variable input resistors R11, R12 and R13, respectively.
v, Pw are connected, and its non-inverting input terminal is connected to a resistor R
It is grounded via 14. Further, the output terminal of the operational amplifier OP3 is connected to the point G via a resistor R15.

Further, the output terminal of the operational amplifier OP3 is connected to the operational amplifier O.
It is connected to the output terminal P via a voltage follower using P4 and a resistor R16. This voltage follower converts impedance by increasing input impedance and decreasing output impedance.

The resistors R11 to R16 and the operational amplifier OP3°OF2
The adder circuit 22 is configured by:

To explain the power supply circuit 23, a power supply transformer 24 is connected to the 100■AC power supply terminal;
A full-wave rectifier 25 is connected to the secondary side of 4. A grounding wire E2 is connected to point d on the secondary side of the power transformer 24, and a smoothing capacitor C14 and a capacitor C15 are connected between the positive terminal of the full-wave rectifier 25 and the grounding wire E2. There is.

In addition, a three-terminal regulator 26 is connected to the positive terminal of the full-wave rectifier 25 and the grounding wire E2, and the output terminal of the = terminal regulator 26 is connected to the 10 Vcc terminal, and the output terminal of the three-terminal regulator 26 is connected to the ground wire E2. A capacitor C8 and a capacitor C9 are connected between the grounding wires 52.

Furthermore, a smoothing capacitor C10 and a capacitor C11 are connected between the negative terminal of the full-wave rectifier 25 and the grounding wire E2. Further, a three-terminal regulator 27 is connected between the negative terminal of the full-wave rectifier 25 and the grounding wire 52.
The output terminal of the three-terminal regulator 27 is connected to the -Vcc terminal, and a capacitor 012 and a capacitor C13 are connected between the output terminal of the three-terminal regulator 27 and ground tE2.

Now, the operation of the switch configured as described above will be explained.

In FIG. 1, a voltage sensor Su is provided corresponding to the connection terminal 38 of each phase as a charging section in the distribution line system.

Sv and Sw are spaced apart from each other by approximately the same distance 1. When a three-phase voltage according to normal phase rotation is applied to the connection terminal 38, the capacitances ICu and c formed between the connection terminal 38 and the ground, which is a reference potential point, are respectively
The displacement current flowing through V, cw passes through the window hole 5 of each voltage sensor Su, Sv, 3W as a displacement current inflow part to the detector tf! Collected by io.

Then, this displacement current is applied to each voltage sensor SU, Sv, Sw.
The displacement current is applied to the amplifier circuit A of the signal processing circuit 8, and the amplifier circuit A amplifies the displacement current and outputs a waveform similar to the displacement current to the operational amplifier OP2.

In this case, terminal P1. The input impedance seen from P2 is considered to be the series value of resistor R1 and resistor R2. As is well known, in the typical usage example of an operational amplifier, the resistor R2
The value is on the order of Ω.

Closed loop gain R4/R2 is 10 to obtain sufficient output.
It is taken around 00. In addition, the resistance R1 is set to a value lower than the creepage leakage resistance of the support member 6 for the detection electrode 10, and is used for stabilizing the input or finely adjusting the output.
It is on the order of Ω to 0.

Therefore, the above-mentioned input impedance is effectively kept at a sufficiently low value by the resistor R2, yet a large signal is obtained at the output of the operational amplifier ZOP1 due to the high closed-loop gain. As is well known, the phase difference between the input and output of the operational amplifier OP1 changes depending on the magnitude relationship between the impedances of the resistor R4 and the capacitor C1, and if the former is relatively small, the phase difference is ignored and the output is proportional to the displacement current. can get. In the opposite case, the phase difference is close to 90", and the output horn provides an integral value of the displacement current, that is, a value proportional to the potential of the distribution line. In any case, this output has a waveform similar to the displacement current. can get.

Next, when a signal similar to the displacement current is applied via the operational amplifier OP2 constituting the voltage follower, the bandpass filter B selectively selects a signal having a center frequency of 60Hz or 50Hz based on the signal. Amplify and extract. Addition circuit 22 of zero-phase voltage detector 20
synthesizes the signals output from each of the voltage sensors 3u, 3v, and 3w selected at a predetermined frequency and outputs a zero-phase voltage 0 signal to its output terminal P (see FIG. 7). In this Fig. 7, α, β, γ are each distribution line LLJ, Lv, 1w
This is the waveform of the voltage applied to.

As described above, in the normal case, the ground voltages of each phase are balanced, so the zero-phase voltage VO obtained by combining in the adding circuit 22 becomes O. Note that this state is initially set when the present switch is installed in the power distribution system. With this initial setting, displacement currents of other phases with different phases flow into each voltage sensor, although slightly, and there is also a slight difference in the effective gain of each phase voltage sensor, so that the ground voltage of each phase is balanced. Since a zero-phase output is generated at the output terminal P even if the output terminal P is set, the resistors R11, R12, and R13 are changed respectively.

Next, if a ground fault occurs in one of the distribution lines connected to the connection terminal 38 of each phase, the balance of the ground voltage of each phase will be disrupted, so each voltage sensor Su, Sv,
When the signals outputted to the zero-phase voltage detector 20 via the signal processing circuit 8 of Sw are combined in the adding circuit 22, a zero-phase voltage is detected.

As a result, it is detected that a ground fault has occurred in the power distribution line.

Also, the frame body 32 is grounded, and the connection terminal 38 is connected to the frame body 32.
Since there is no change in the relative position between the voltage sensor Su, 3v, and Sw, there is no change in the relative position between the detection electrode 10 of the voltage sensor Su, 3V, and Sw and the grounding part closest to the detection electrode 10. Because it uses a charged part with a constant interphase spacing, there is no change at all due to the influence of other phases, and the connection terminal 3
Detection of the displacement current from 8 is performed accurately.

In addition, the voltage sensors 3u, 3v, and 3w have a case 1 and a lid 3 that act as shields to effectively prevent displacement current from flowing in from sources other than the distribution line that is the object to be detected.
There is virtually no negative influence from other power distribution lines other than the power distribution line that is the object to be detected.

FIG. 8 shows a second embodiment embodied in a closed type switch.

In addition, the same reference numerals are attached to the same or corresponding configurations as those of the first embodiment, and the explanation thereof will be omitted.

In this embodiment, bushings 48 and 49 on the power supply side and the load side for each phase are penetrated and fixed to both side walls of the grounded sealed case 47, and a hanging metal fitting 50 is attached to the upper part of the load side of the sealed case 47. Voltage sensors Su, Sv, and Sw are suspended and supported through the bushings, and are arranged directly above the four bushings.

Therefore, the voltage sensors Su, Sv of this embodiment.

The SW is inserted into the bushing 49 and detects the displacement current from the conductor rod 49a serving as a charging portion connected to the power distribution line 49b. Note that 51 is an opening/closing operation handle rotatably attached to the case 47.

The effects of this embodiment are similar to those of the previous embodiment.

Figure 9 shows the third embodiment of the rotary type exposed switch.
In this embodiment, an opening/closing shaft 52 is rotatably supported in the lower part of the grounded frame 32 in the mutual direction.
A movable insulator 53 is integrally fixed to each phase. The movable insulator 53 [The movable electrode 54 is fixed,
By operating the movable electrode 54 and the operating handle 44 and rotating the opening/closing shaft 52, it comes into contact with and separates from a pair of fixed electrodes (not shown) mounted within the main insulator 33.

Voltage sensors Su, Sv, and Sw are suspended from the upper part of the load side of the frame 32 via hanging fittings 45.
The connecting terminal 55 is protruded from both sides of the main body insulator 33 and is arranged directly above the connecting terminal 55 as a charging section connected to the fixed electrode. Note that 56 is an insulating cover arranged to cover the outside of the connection terminal 55.

Therefore, the voltage sensors su, sv of this embodiment.

The SW detects the displacement current from the connection terminal 55.

Note that arbitrary changes can be made without departing from the spirit of the invention.

Effects of the Invention As detailed above, the present invention provides a switch in which the machine frame, case, etc. of the switch are grounded to form a grounding part, and the grounding part and a charged part such as a conductor rod inserted through the bushing are connected to each other. Since the relative positions do not change and are stable, there is no change in the relative position between the detection electrode of the voltage sensor and the grounding part closest to the detection electrode, making it possible to accurately detect the displacement current from the charged part. Therefore, it is possible to easily detect ground faults in distribution line systems.

[Brief explanation of drawings]

Fig. 1 is a front view of a switch according to an embodiment of the present invention, Fig. 2 is a conceptual diagram, Fig. 3 is a cross-sectional view of a voltage sensor, Fig. 4 is a view from the same perspective, and Fig. 5 is a diagram. Similarly, the electric circuit diagram of the signal processing circuit, Figure 6 is the electric circuit diagram of the detection circuit of the zero-phase voltage detector, and Figure 7 is the zero-phase voltage detected by this zero-phase voltage detection device and the voltage of each phase distribution line. Oscillograph, Figure 8 is the second
FIG. 9 is a front view of the switch of the third embodiment. DESCRIPTION OF SYMBOLS 1... Shield container, 2... Base, 3... Lid case, 5... Window hole, 6... Rod-shaped support member, 8...
Signal processing circuit, 10... Detection electrode, 20... Zero-phase voltage detector, 21... Detection circuit, 38... Connection terminal (
Charging section), A...Amplification circuit, 8...Band pass filter, El, E2...Grounding wire, OP1 to OP4...
Operational amplifier, R1-R16...Resistor, C1-C15...
...Capacitor, Pl...Input terminal, P2...Terminal, Pu, Pv, Pw...Output terminal, Cu, CV, CW
---Capacitance, lu, lv. LW...Power distribution line, 3u, 3v, 3w...Voltage sensor. Patent applicant: Nippon Insulators Co., Ltd. Takamatsu Electric Manufacturing Co., Ltd. Representative Patent attorney On 1) Hironobu Figure 2

Claims (1)

[Claims] 1. A window hole is provided in the upper surface of an electrically grounded shielding container made of a conductive material, and inside the container there is a plate supported by a rod-shaped support member having folds made of an insulating material. A shaped detection electrode is disposed on the upper surface of the detection electrode such that the window hole is closed with a gap between it and the inner surface of the container, and the detection electrode is provided with an amplifier circuit and a bandpass filter. A voltage sensor is configured by connecting a signal processing circuit consisting of switch.