CN2252433Y

CN2252433Y - Anti-overvoltage and overcurrent protector for telecommunication system

Info

Publication number: CN2252433Y
Application number: CN 95246242
Authority: CN
Inventors: 买云; 马培勇
Original assignee: Individual
Current assignee: Individual
Priority date: 1995-11-24
Filing date: 1995-11-24
Publication date: 1997-04-16
Anticipated expiration: 2005-11-24

Abstract

The utility model relates to an anti-overvoltage and overcurrent protector for remote telecommunication systems, which is composed of an overcurrent protection circuit, a primary overvoltage protection circuit, a secondary overvoltage protection circuit, a protection matching circuit, a shell body, etc. The utility model adopts conduction type transient semiconductor elements, provides effectively protection for telecommunication equipment in communication lines of local calls, and has the advantages of quick response speed, self-restoring, etc. The adoption of the overcurrent protection circuit can prevent generant overcurrent influence because of power line contact, and telecommunication equipment is free from damage; circuits can bear higher transient impact voltage with the adoption of a multi-stage protection circuit, protective precision is higher simultaneously, and the remote telecommunication systems can normally and safely work without influence.

Description

Telecommunication system is prevented overvoltage, overcurrent protective device

The utility model relates to a kind of protective device, and particularly a kind of telecommunication system is prevented overvoltage, overcurrent protective device.

Disclose in the Chinese patent (patent No. 89204151.0) by a kind of " computer lightning arrester "; though adopt multistage combined protection scheme; the anti-induction lightning impulse voltage there is certain effect; but because of there not being anti-overcurrent function; when power line taking place (as 220V; 50HZ is alternating current frequently) when coming in contact fault (this class situation happens occasionally in telecommunication system) with communication line; its protective circuit action; shorted to earth produces and continues big electric current; the distance protection circuit is nearer when the fault point; under the less situation of line resistance; protective circuit is damaged, more caused protection module to catch fire when serious.

The purpose of this utility model is to avoid above-mentioned the deficiencies in the prior art part and provides a kind of telecommunication system that has overvoltage, the dual multi-stage protection function of overcurrent concurrently to prevent overvoltage, overcurrent protective device.

The purpose of this utility model can reach by following measure: the utility model comprises first order overvoltage crowbar, second level overvoltage crowbar, housing, it is characterized in that; Also have current foldback circuit, protection match circuit, current foldback circuit and first order overvoltage crowbar join, and are connected to the protection match circuit between first order overvoltage crowbar and the second level overvoltage crowbar.

The purpose of this utility model can also reach by following measure: electronic circuit board is housed in the housing, and joins by socket, plug and outside line and protected equipment respectively.Current foldback circuit is made of two thermistor PTC1, PTC2; discharge tube F1 in it and the first order overvoltage crowbar joins, and discharge tube F1 joins by 2,4 pin of integrated circuit (IC) 1 in resistance R 1, R2 and the second level overvoltage crowbar in the protection match circuit respectively.Integrated circuit (IC) 1 is a conducting type transient state semiconductor chip, and model is 200S.

Fig. 1 is a functional-block diagram of the present utility model;

Fig. 2 is a contour structures schematic diagram of the present utility model;

Fig. 3 is an electrical schematic diagram of the present utility model.

With reference to Fig. 1, Fig. 2, the utility model is made up of current foldback circuit 1, first order overvoltage crowbar 2, protection match circuit 3, second level overvoltage crowbar 4, housing 5, socket 6, plug 7 etc.Electronic circuit board is loaded in the housing 5, and this device can directly be contained in device communication interface places such as modulator-demodulator, facsimile machine or group telephone, and can pass through socket 6, plug 7 connections.

With reference to Fig. 3; current foldback circuit 1 is made up of two thermistor PTC1, PTC2; the key property of PTC is under normal circumstances; its internal resistance is minimum; when overcurrent took place, its internal resistance meeting sharply increased with multiple, effectively big electric current was limit to little electric current; after fault was got rid of, PTC can automatically reset.

The first elementary overvoltage crowbar 2 mainly is made up of discharge tube F1 (or piezo-resistance), and its purpose is on the one hand when the transient overvoltage energy is big, and the discharge tube action releases most energy to greatly.Provide current circuit for circuit overcurrent protection on the other hand.

Second level excess voltage protection 4 is based on the two-way transient state semiconductor device of conducting type (the two-way transient state semiconductor diode of conducting type for example; conducting type transient state semiconductor integrated chip IC1 etc.); the effect of this circuit is to select suitable electric pressure according to protected communication equipment; meticulous transient protective is provided; its response time can be born 1000V 10/700 μ s simulation shock test less than 1ns.

Protection match circuit 3 is made of resistance R 1, R2; it not only provides current-limiting function for second level overvoltage protective module; also provide Circuit Matching for first order overvoltage protection and second level overvoltage protection; to guarantee close fit between the two; macro-energy and fast-response are combined; the characteristics that quick response is promptly arranged, can ensure again that second level protective circuit is avoided bearing than macro-energy impacts.

PTC1 and PTC2 are positive temperature thermistor among the figure; F1 is three grades of discharge tubes (3R-230) of nominal voltage 230V; R1, R2 are current-limiting resistance; IC1 is a conducting type transient state semiconductor integration member, model 200S.

When power line contact etc. taking place very during fault; discharge tube F1 and IC1 all move; the big electric current of circuit by PTC1, PTC2 after the overwhelming majority release over the ground via F1, PTC reacts to overcurrent and causes open circuit, thereby has protected late-class circuit and protected communication apparatus not to be damaged.After fault was got rid of, PTC can recover proper communication automatically.

When communication line suffers lightning induction or power induction; IC1 (200S) is because operation voltage is low; transient response at first; and be conducting state to protect back level communication equipment; because the existence of current limliting build-out resistor R1, R2, the discharge tube F1 conducting of discharging will rapidly be released main energy to greatly.

In view of present part PTC product impact resistance relatively a little less than, therefore also can before PTC1 and PTC2, distinguish the discharge tube of adjunction nominal value 470V (the 470V discharge tube is failure to actuate) over the ground under over-current state.

The utility model has following advantage compared to existing technology:

1, telecommunication equipment (such as modem, facsimile machine, group telephone etc.) is held concurrently Overvoltage, the dual multi-stage protection function of overcurrent are arranged.

2, adopt conducting type transient state semiconductor devices, making the communication media with the local telephone communication system Communication line in can effectively provide protection to communication equipment, and have fast response time, from The characteristics such as the property recovered.

3, adopt circuit overcurrent protection, can prevent because the overcurrent influence that power line contact etc. produce is not damaged communication equipment.

4, adopt the multi-stage protection circuit, can make circuit can bear higher transient impact voltage, can reach 6000V.Protect precision higher simultaneously.System does not have influence to telecommunication, can safe proper communication.

Claims

1, the anti-overvoltage of a kind of telecommunication system, overcurrent protective device comprise first order overvoltage crowbar 2, second level overvoltage crowbar 4, housing 5, it is characterized in that; Also have current foldback circuit 1, protection match circuit 3, current foldback circuit 1 joins with first order overvoltage crowbar 2, is connected to protection match circuit 3 between first order overvoltage crowbar 2 and the second level overvoltage crowbar 4.

2, device according to claim 1 is characterized in that: in the housing 5 electronic circuit board is housed, and joins with outside line and protected equipment by socket 6, plug 7 respectively.

3, device according to claim 1; it is characterized in that: current foldback circuit 1 is made of two thermistor PTC1, PTC2; discharge tube F1 in it and the first order overvoltage crowbar 2 joins, and discharge tube F1 joins by 2,4 pin of integrated circuit 1C1 in resistance R 1, R2 and the second level overvoltage crowbar 4 in the protection match circuit 3 respectively.

4, device according to claim 1 is characterized in that: integrated circuit (IC) 1 is conducting type transient state semiconductor chip, and model is 200S.