JPH0618570A - Zero-phase voltage detecting device - Google Patents

Abstract

PURPOSE:To obtain a zero-phase voltage detecting device which can be easily inspected in a normal state. CONSTITUTION:The title detecting device is constituted of voltage detecting sections 14 provided to each phase, a signal synthesizing section 56 which synthesizes the voltage signals of the sections 14, and a signal line 57 which transmits the synthesized zero-phase voltage to a signal control section. In each voltage detecting section 14, a capacitor 42 is connected in parallel with a voltage dividing electrode and capacitor 42 and a voltage sensor head 43 detects a voltage. In addition, a capacitor section 46 for inspection which is connected to one 14a of the voltage detecting sections 14 by means of an external switch Sw at the inspecting time is connected to the section 14a in parallel with the capacitor 42. When the switch Sw is turned on, the capacitance becomes unbalanced and a zero-phase voltage is generated in a simulated state. The zero-phase voltage is used for inspecting devices for faults.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a zero-phase voltage detecting device for detecting the occurrence of an accident in a three-phase electric line.

[0002]

2. Description of the Related Art In a three-phase distribution line circuit, monitoring devices are installed at various places to detect line accidents and isolate faulty sections.
The current or voltage of the electric circuit or its zero-phase component is detected. As the zero-phase voltage detecting device, for example, a zero-phase detecting section is provided in the vicinity of an electric wire or a conductor of a line device, and each voltage detected by the voltage detecting section is combined into a zero-phase voltage. The zero-phase voltage is input to a signal control unit installed in the monitoring device to control the opening and closing of the electric circuit based on the current and voltage and various data of these zero-phase components.

[0003]

The normal zero-phase voltage shows a value of zero because each phase of the electric circuit is balanced. However, even if a failure occurs in the zero-phase voltage detection device, the signal control section still shows a value of zero, so that this failure cannot be found. For this reason, it is necessary to perform inspection work such as applying a power supply voltage in a simulated manner to confirm that the signal control unit operates normally in the event of an accident.

An object of the present invention is to provide a zero-phase voltage detecting device which can be easily inspected under normal conditions.

[0005]

In order to achieve the above-mentioned object, a voltage detecting section is provided with a voltage dividing electrode provided around each phase conductor and in parallel with the voltage dividing electrode and grounded. Check that consists of a built-in capacitor and a voltage sensor head that detects each shared voltage shared by the voltage dividing electrode, and that can be connected and disconnected by an external switch to the voltage detection part of at least one phase of the three-phase electric circuit. The capacitor part for use is provided in parallel with the capacitor.

[0006]

In the voltage detecting section, voltage dividing electrodes are provided around the conductors of the respective phases to divide the voltage applied to the conductors. The voltage dividing electrode is provided with a grounded capacitor in parallel, and each shared voltage is detected by the voltage sensor head. The respective voltage signals detected by the respective voltage sensor heads are combined by the signal combining section into a zero-phase voltage signal.

The zero-phase voltage signal is not output during normal times because the three phases are in a balanced state. In addition, when a ground fault occurs, the phase of the voltage applied to the conductor that caused the ground fault shifts,
A fault voltage signal is output.

During inspection, when the external switch of the inspection capacitor unit connected to any one-phase voltage detection unit is closed, the inspection capacitor unit provided in parallel with the capacitor is connected, Only this one-phase capacitance increases. Therefore, an imbalance occurs between the voltage of this one phase and the voltage of the other phase, and the combined zero phase voltage is generated to output the signal, so that the zero phase voltage detection device functions normally. You can check that you are.

According to the invention of claim 2, in addition to the operation of the invention of claim 1, a voltage dividing electrode, a voltage sensor head,
Since the capacitor and the inspection capacitor are integrally attached to the case, they can be easily attached to the electric circuit.

[0010]

According to the present invention, the voltage detecting section includes a voltage dividing electrode provided around each phase conductor, a capacitor provided in parallel with the voltage dividing electrode and grounded, and the voltage dividing electrode. It is composed of a voltage sensor head that detects each shared voltage shared by, and at least one of the phases of the three-phase circuit is equipped with an inspection switch that can be connected and disconnected by an external switch in parallel with the capacitor. Therefore, the zero-phase voltage detection device can be easily inspected in the normal state.

[0011]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An example in which the zero-phase voltage detecting device of the present invention is attached to a switch 1 of a power distribution line will be described in detail below. As shown in FIG. 2, the switch 1 has a hanging bracket 2 and a pole 3 of a utility pole.
It is hung and installed by being hooked on the hook metal fitting 4. Bushings 6 for drawing in the conductors U, V, W of the three-phase electric circuit are attached to the outer shells on both sides of the main body case 5 of the switch 1. The conductors U, V, W are connected to open / close terminals (not shown) to open / close the electric path.

A control box 7 is provided on one side of the body case 5, and an opening / closing operation mechanism 8 for opening / closing the opening / closing terminal and an opening / closing control mechanism 9 for controlling the opening / closing are housed. . A manual operation lever 11 is provided outside the control box 7 on an operation shaft 10 for manually operating the opening / closing operation mechanism 8 so that the opening / closing terminal can be opened / closed. In addition, an electric connector 12 is provided on the bottom of the control box 7.
The signal line 13 is led out in an airtight state by. The signal line 13 is connected to a signal control unit (not shown) and drives the opening / closing operation mechanism 8 based on the drive signal to open / close the electric circuit.

Inside the main body case 5, there are respectively attached cases 15 through which the bushings 6 are inserted and the current detecting section and the voltage detecting section 14 are attached. Necessary components are integrally attached to the case 15, and an attachment flange 16 formed on the outer edge is attached to the main body case 5 with a metal attachment screw 17 (see FIG. 3). This case 15
Have almost the same structure in each phase. In FIG.
An inspection capacitor section 46 described later is added only to the right case 15a. The case 15a on the right side will be described below.

As shown in FIG. 3, the case 15a, which is formed in a thin cylindrical shape, is fitted with the bushing 6 inserted into the hollow portion 21 formed by the inner wall 20. An outer wall 22 is concentrically provided on the outer side of the inner wall 20, and an annular storage groove 23 is formed between the inner wall 20 and the outer wall 22. The lower part of the storage groove 23 is open, and the mounting plate portion 24 is continuously extended.

The current detecting portion of the case 15a will be described. An annular magnetic core 25 having a rectangular cross section is accommodated in the accommodating groove 23. The core 25 is cut out at a lower portion to provide a gap 26. The head of the magnetic field sensor head 27 is inserted into the gap 26, and is screwed by the clamp 28. The magnetic field sensor head 27 has a detection unit built in its head, detects a change in the magnetic field due to the current flowing through the conductor W, and converts it into an optical signal proportional to its strength. The converted optical signal is connected by an optical fiber 30 via an optical connector 31 attached to the bottom of the main body case 5 to a signal generating / processing unit 50, which will be described later, which is attached to an intermediate portion of the electric pole. In this embodiment, the core 25 is arranged concentrically with the conductor W arranged at the axial center of the bushing 6, and the head portion is provided in the gap 26 so as not to be affected by the magnetic fields of the conductors U and V of other phases. Since it is inserted, the change in current can be detected accurately. Further, since the detected current signal is converted into an optical signal, it can be accurately transmitted without being guided by the outside world.

Explaining the voltage detector 14 of the case 15a, a voltage dividing electrode 36 made of a strip-shaped thin plate is arranged in a loop along the inner wall 20 in the storage groove 23 in which the core 25 is stored. A ground electrode 37, which is also a strip-shaped thin plate, is arranged in a loop along the outer wall 22. The end of the ground electrode 37 is attached by a metal mounting screw 38, and the mounting screw 38 and the mounting flange 16 are connected by a ground wire 39 to be grounded.
Therefore, the voltage dividing electrode 36 and the ground electrode 37 are arranged so as to face each other with the core 25 interposed therebetween with a predetermined gap, and the voltage applied to the conductor W can be accurately divided. In addition, the core 25, the voltage dividing electrode 36, and the ground electrode 37 are provided in the housing groove 23, and are filled and covered with a mold body (not shown).

The connection terminal 40 of the voltage dividing electrode 36 is the mounting plate 2
It is extended in four directions, and is connected to the voltage sensor head 43 through one end of a capacitor 42 for correcting the capacitance of the electrostatic capacitance C1 by a lead wire 41. A lead wire 44 connected to one end of the ground electrode 37 is connected to the voltage sensor head 43 via the other end of the capacitor 42.
The voltage sensor head 43 is configured to convert the line voltage divided by the electrostatic capacitance C1 generated between the voltage dividing electrode 36 and the ground electrode 37 into an optical signal by the Pockels element. This optical signal is connected to the signal generating / processing unit 50 via the optical connector 31 attached to the bottom of the main body case 5 by the optical fiber 45.

Further, only in the voltage detecting section 14 on the right side,
An inspection capacitor unit 46 is provided in parallel with the capacitor 42. An inspection capacitor 46a having the same electrostatic capacity as the electrostatic capacity C1 of the capacitor 42 and a normally open relay switch 47 are connected to the inspection capacitor section 46. The relay switch 47 can be opened / closed by the opening / closing operation of the external switch Sw to connect the inspection capacitor section 46 to the capacitor 42.

Further, as shown in FIG. 1, a signal generating / processing unit 50 for operating the voltage sensor head 43 is installed in a box (not shown) attached to the middle portion of the electric pole. The signal generating / processing unit 50 is provided with a light emitting module 52 driven by a driving power source 51, and a light receiving module 54 for receiving an optical signal polarized by the voltage sensor head 43 by this light emission and converting it into an electric signal.
Is provided. The converted electric signal is corrected and amplified by the correction amplifier 55, vector-combined by the signal combiner 56, and the zero-phase voltage signal is transmitted to the signal controller (not shown) via the signal line 57 for display.

Next, the operation of this embodiment will be described.

In the normal state, each light emitting module 52 emits light by each driving power source 51, and the input light is supplied to each voltage sensor head 43. Then, the Pockels element in the voltage sensor head 43 transmits the optical signal polarized according to the divided voltage based on the voltage dividing electrode 36 to the light receiving module 54, and after being converted into an electric signal, the correction amplifying unit 55 causes the signal synthesizing unit 56. Be transmitted to. In a normal state, since the voltages of the respective phases of the three-phase electric circuit are balanced, the combined voltage (zero-phase voltage) of the corrected and amplified voltages of the respective phases becomes zero. Therefore, the signal control unit detects the zero-phase voltage signal 0 transmitted through the signal line 57.

When a ground fault occurs, the equilibrium state of the voltage of each phase is broken and the zero-phase voltage synthesized by the signal synthesizer 56 is output to the signal controller. A ground fault is detected based on the value of the zero-phase voltage. Further, in addition to the zero-phase voltage, the voltage of each phase, the current signal, and the like are combined to generate a signal for driving the opening / closing operation mechanism 8 when the accident occurs, and the switch 1 opens the electric circuit. It will be released.

In order to perform the above-mentioned operation, it is necessary that the system of the signal generating / processing section 50, the signal line 57, etc. be kept in a healthy state. To perform this check, the external switch Sw is closed. As a result, the relay switch 47 is closed, and the capacitance of only one phase of the voltage detection unit 14 of the conductor W changes. In this embodiment, the inspection capacitor 4
Since the electrostatic capacity C2 of 6a is made equal to the electrostatic capacity C1 of the capacitor 42, the detected voltage V2 is V2 = C2 / (C1 + C) with respect to the initial detected voltage V1 in each phase.
2) The relationship of V1 is established, and the zero-phase voltage of 0.5V1 is generated by the vector composition of the three-phase voltages. Therefore, the equilibrium state of each phase is broken, and the simulated zero-phase voltage is output from the signal combining unit 56 to the signal control unit. Accordingly, the voltage detector 14
Also, it can be confirmed that the system such as the signal generation / processing unit 50 and the signal line 57 is kept in a healthy state.

Further, in this embodiment, since the voltage detecting portion 14 in the zero-phase voltage detecting device is a unit integrated with the case 15, the mounting on the electric line is easy and the stable function is maintained for a long period of time. To be done.

In this embodiment, the external switch Sw is provided in the operation box provided in the middle of the electric pole. However, it may be provided in a monitoring station which supervises each monitoring device.

[Brief description of drawings]

FIG. 1 is a circuit diagram of a voltage detection unit.

FIG. 2 is a partially cutaway side view of a switch.

FIG. 3 is a partial cross-sectional view of a case.

[Explanation of symbols]

 14 ... Voltage detecting unit 36 ... Voltage dividing electrode 42 ... Capacitor for capacity correction 43 ... Voltage sensor head 46 ... Inspection capacitor unit 50 ... Signal generating / processing unit 51 ... Driving power supply 56 ... Signal combining unit 57 ... Signal line U, V, W ... conductor

Claims (2)

[Claims] 1. A voltage detecting section for detecting a voltage applied to each phase of a three-phase electric circuit, a signal combining section for combining the detected voltage signals of the respective phases, and a signal control for the combined zero-phase signal. In the zero-phase voltage detection device consisting of a signal line transmitted to the section, the voltage detection section is provided with a voltage dividing electrode provided around the conductor of each phase and provided in parallel with the voltage dividing electrode and grounded. An inspection capacitor that consists of a capacitor and a voltage sensor head that detects each of the divided voltages shared by the voltage dividing electrodes, and that can be connected to and separated from the voltage detection section of at least one phase of the three-phase circuit by an external switch. A zero-phase voltage detecting device, wherein a part is provided in parallel with the capacitor. 2. A voltage detecting portion is integrally attached to a case, and a strip-shaped voltage dividing electrode is provided on the outer surface of an inner wall forming a hollow portion into which a conductor is inserted, and the inner wall and A band-shaped ground electrode, which is grounded, is provided on the inner surface of the outer wall that is concentrically provided, and a capacitor for capacitance correction connected to the voltage dividing electrode and a voltage sensor that detects the voltage and converts it into an optical signal. 2. The zero-phase voltage detection device according to claim 1, wherein a voltage detection unit including a head and an inspection capacitor unit connected in parallel with the capacitor are integrally mounted and arranged in a case.