CN2701140Y

CN2701140Y - Artificial ground shunt and self-recovery type arc extinguishing device

Info

Publication number: CN2701140Y
Application number: CN 200420025259
Authority: CN
Inventors: 唐轶; 陈庆; 陈奎
Original assignee: China University of Mining and Technology CUMT
Current assignee: China University of Mining and Technology CUMT
Priority date: 2004-03-05
Filing date: 2004-03-05
Publication date: 2005-05-18
Anticipated expiration: 2014-03-05

Abstract

The utility model provides an artificial ground shunt and self-recovery type arc extinguishing device, which is connected by three groups of normally open contacts connected with an electric network, three groups of normally open contacts, three groups of normally closed contacts, an electric resistance, a voltage-sensing varistor, a current transformer, a three-phase potential transformer and a controller. When the electric network generates single-phase grounding fault, the controller judges the phase of the single-phase grounding fault, the normally open contact of the corresponding phase is closed, and artificial shunt is realized; when the fault is eliminated, three groups of normally closed contacts are opened respectively, the shunt circuit is cut, and the initial condition is automatically recovered. The artificial ground shunt and self-recovery type arc extinguishing device has simple structure, easy mount, good effect and wide practicability.

Description

Artificial ground shunting self-recovering type arc-extinction device

One, technical field

The utility model artificial ground shunting self-recovering type arc-extinction device relates to and presses low current neutral grounding electric network in a kind of the directly applying to, and effectively reduces single phase ground fault point residual flow, effectively suppresses the superpotential electric network protection device of intermittent electric arc.

Two, background technology

China's medium voltage network is low current neutral grounding electric network.When power-to-ground capacitance is big, earth current is bigger, earth fault electric arc is difficult for from going out, cause easily other faults and take place, but since arc suppression coil only can compensation network capacitance current, therefore, when the single-phase-to-ground current of electrical network is big, bigger residual flow is arranged behind arc suppression coil compensation, and generally about 10%, this will influence the success rate of extinguishing arc.The residual flow that the artificial ground shunting then can be controlled earth fault goes to zero, and therefore, extinguishing arc has higher success rate.Arc suppression coil is an inductance, and its electric current can not suddenly change, and therefore, the capacitance current of arc suppression coil compensation electrical network has a process (time).In this process, indirect arc still will produce overvoltage, experiment and operating experience prove: arc suppression coil can reduce the probability that overvoltage takes place, but can not eliminate overvoltage fully, artificial ground shunting can the control action time, grounding shunt is a real earth point, can not produce intermittent electric arc overvoltage, thereby safer.

Three, technology contents

(1) goal of the invention

The utility model artificial ground shunting self-recovering type arc-extinction device, when electrical network generation single phase ground fault, this device can make the residual flow of earth fault go to zero, and ground arc extinguishes immediately, after treating that earth fault is eliminated, this device will recover normal power supply immediately automatically.

(2) technical scheme

The utility model artificial ground shunting self-recovering type arc-extinction device, by with the three-phase bus of neutral non-effective grounding electrical network and ground between the three groups of controlled normally opened contacts of connecting, be called artificial shunting ground connection normally opened contact, the circuit that series connection one is made up of normally-closed contact and resistance, ground connection behind the series current instrument transformer again, one group of normally-closed contact of being connected be 1-3 only, in the normally-closed contact except that one is directly connected, all the other several the backs of connecting with resistance are parallel with one another, an overall resistance in parallel.Entire circuit is in parallel with the varistor group, and varistor plays the overvoltage protection effect, and the controller circuitry with the mutual device serial connection of three-phase voltage composes in parallel again.The circuit that normally-closed contact and resistance are formed, parallel with one another by one group of normally-closed contact, series resistance not wherein, all the other several all are in series with resistance, overall a resistance in parallel, then ground connection behind the series current instrument transformer.When electrical network generation single phase ground fault, this device makes the normally open contact closure of the corresponding fault phase of control, forms an artificial grounding shunt point, and this artificial ground point ground connection is good, and the electric current of former single phase ground fault point is gone to zero, and electric arc extinguishes immediately.After single phase ground fault is eliminated, this device divides and reduces artificially branch flow valuve for several times, and number of times is identical with the number of normally-closed contact, proves all that through verifying several times single phase ground fault eliminates, then device will withdraw from the artificial ground shunting immediately, make electrical network automatically restore to normal operating condition.

(3) technique effect

The utility model can make the residual flow of single phase ground fault point go to zero, and earth point electric arc is thoroughly extinguished, and eliminates the overvoltage that causes because of single phase ground fault.Simultaneously, single phase ground fault can return again after disappearing immediately automatically, and electric network single-phase earth fault is prolonged running time.Because the intervention of " artificial ground shunting " makes one of low current neutral grounding electric network the biggest problem---the problem of " low current neutral grounding electric network earthing wire-selecting " is able to good solution." artificial ground shunting " is that " low current neutral grounding electric network earthing wire-selecting " provides more judging characteristic and judged chance, the automatic return course of device increases more judging characteristic and chance for again " low current neutral grounding electric network earthing wire-selecting ", and the failure line selection judgment accuracy of " low current neutral grounding electric network earthing wire-selecting " is greatly improved.The utility model can reduce the overvoltage that causes because of single phase ground fault effectively, and other faults that may cause, and guarantees electric power netting safe running.

Four, description of drawings:

Accompanying drawing is the utility model circuit theory diagrams.

Five, embodiment

Below in conjunction with accompanying drawing an embodiment of the present utility model is described further: the utility model artificial ground shunting self-recovering type arc-extinction device, with controlled three groups of normally opened contact CA, CB, the CC that connects between the three-phase bus of neutral non-effective grounding electrical network and the ground, three groups of normally-closed contact C1, C2, C3 and resistance R 1, R2, R3 connect, ground connection behind the series current instrument transformer H again, entire circuit connects controller with the mutual device PT of three-phase voltage and composes in parallel once more with after varistor group PR is in parallel.It is characterized in that: between artificial shunting ground connection normally opened contact CA, CB, CC and ground connection, be connected with a circuit, this circuit is by three groups of normally-closed contact C1, C2, C3, and wherein two windings point is in series with resistance R 1, R2, overall a resistance R 3 in parallel, then ground connection behind the series current instrument transformer H.When electrical network normally moved, CA, CB, CC often opened, and C1, C2, C3 are normally closed, and when electrical network generation single phase ground fault, controller is judged the single phase ground fault phase of electrical network, and made contactor closure corresponding among CA, CB, the CC, realized " artificial shunting ".Controller is measured electric current I f by instrument transformer H, and after time-delay a period of time, controller is opened C1, and surveys electric current I f again, if earth fault is not eliminated, then makes C1 closed again; If earth fault is eliminated, then continue to open the C2 electric current I f that tests oneself, judge that earth fault eliminates not, if earth fault is not eliminated, then closure makes C2 closed again again, if earth fault is eliminated, C3 is opened, the electric current I of testing oneself f, after three conclusive evidence earth faults like this are eliminated really, withdraw from " artificial ground shunting ", promptly separate corresponding contactor among CA, CB, the CC, close then C1, C2, C3 contactor.

Claims

1. an artificial ground is shunted the self-recovering type arc-extinction device, it comprise by with the three-phase bus of neutral non-effective grounding electrical network and ground between the controlled three groups of normally opened contacts (CA, CB, CC) of connecting, entire circuit is with after varistor group (PR) is in parallel, it is in parallel once more that same threephase potential transformer (PT) connects controller, ground connection after the other end of normally opened contact is connected with a current transformer (H), it is characterized in that: between the described controlled three groups of normally opened contacts (CA, CB, CC) and current transformer, connect one group of normally-closed contact and resistance.

2, artificial ground shunting self-recovering type arc-extinction device according to claim 1, it is characterized in that: one group of normally-closed contact of being connected is 1-3, except that one directly the series connection, all the other several the backs of connect with resistance are parallel with one another, totally a resistance in parallel (R) in the normally-closed contact.