CN2342509Y

CN2342509Y - Anti-fire protector for AC loop

Info

Publication number: CN2342509Y
Application number: CN 98206086
Authority: CN
Inventors: 胡新锁
Original assignee: Individual
Current assignee: Individual
Priority date: 1998-06-29
Filing date: 1998-06-29
Publication date: 1999-10-06
Anticipated expiration: 2008-06-29

Abstract

The utility model relates to an anti-fire protector for an AC loop, which mainly comprises an electronic switch circuit, a sampling circuit and load which are connected in series in the AC loop, wherein the sampling circuit collects fault signals in the AC loop to output to a protection circuit, and the protection circuit emits a control signal to make the electronic switch circuit work; thus, the anti-fire protector can reliably cut off the controlled AC loop within 3 microseconds to 0.01 second. Thereby, the temperature rise or the fire of the AC loop is effectively controlled and the occurrence and the diffusion of electrical fire and explosion accidents are avoided. Therefore, the utility model effectively protects electric equipment and ensures the safety of life and property of a person.

Description

Ac circuit flameproof protection device

The utility model relates to a kind of ac circuit flameproof protection device.

In existing alternating current circuit, because electric wire is aging, random pull the wire, random circuit closer and overload, irregular operation in spite of illness, often cause the generation of phenomenons such as the short circuit of high pressure short, virtual connection sparking, electric leakage, overvoltage and serious overcurrent, very easily cause serious accidents such as electrical fire, explosion accident, electric shock injures and deaths and electric equipment damage.At present mainly adopt the strick precaution mode to solve, i.e. equipped fuse, air switch, thermal relay and various circuit breakers etc. on circuit to the generation of this type of accident.This type of device mainly is by the fusing of fuse and machinery is threaded off or hot dropout mode is cut off alternating current circuit, but the fatal shortcoming of this type of mode is slow in the protection action quick-action of accident generation back, and promptly accident forms before it cuts off alternating current circuit.The poor reliability of such device is very easily malfunctioning simultaneously.

The ac circuit flameproof protection device that the purpose of this utility model is to provide that a kind of cut-off velocity is fast, reliable operation, prevention serious accident take place.

The purpose of this utility model is achieved in that a kind of ac circuit flameproof protection device, and it comprises electronic switching circuit, sample circuit and the load that is serially connected with in the ac circuit, and the output of its sample circuit connects electronic switching circuit through protective circuit.

The overvoltage crowbar that also connects the overvoltage sample circuit in the ac circuit and link with the overvoltage sample circuit, the input of overvoltage sample circuit is connected in the ac circuit, and its output connects electronic switching circuit through overvoltage crowbar.

Sample circuit is made up of sample circuit A and sample circuit B, described sample circuit A is made up of instrument transformer T1, resistance R 0 and rectifier bridge U, the elementary winding of its resistance R 0 and instrument transformer T1 and connect after be serially connected with in the ac circuit, the secondary winding of instrument transformer T1 connects the input of rectifier bridge U; Said sample circuit B is made up of instrument transformer T2 and amplifier IC4, and the two elementary winding L 1 of its instrument transformer T2, L2 are serially connected with respectively in the ac circuit, the secondary input that meets amplifier IC4 of instrument transformer T2.

Protective circuit comprises short-circuit protection circuit, overload protecting circuit and virtual connection protective circuit, and its three also connects between back access sample circuit and electronic switching circuit.Short-circuit protection circuit is made up of resistance R 3-R6, capacitor C 1, voltage stabilizing didoe DW1 and operational amplifier IC1; resistance R 3 is connected in series the two ends, back and accesses the output of sample circuit and the input of amplifier IC1 respectively with diode DW1; its resistance R 4-R6 and capacitor C 1 are the peripheral cell of amplifier IC1, and the output of amplifier IC1 connects electronic switching circuit through resistance R 6.Overload protecting circuit is made up of resistance R 7-R11, capacitor C 2, C3, voltage stabilizing didoe DW2 and operational amplifier IC2; its resistance R 7, R8 are connected in series the two ends, back and access the output of sample circuit and the input of amplifier IC2 respectively with diode DW2, its resistance R 9-R11 and resistance C3 are the peripheral cell of amplifier IC2.The virtual connection protective circuit is by resistance R 12-R19; capacitor C 4-C7; diode VD2; triode VT3-VT5 and operational amplifier IC3 form; the base stage of triode VT3 and VT5 is respectively through resistance R 12; capacitor C 4 and resistance R 14; access the output of sample circuit after the capacitor C 5; the base stage of triode VT4 links through the collector electrode of resistance R 15 with triode VT5; the collector electrode of the emitter of triode VT4 and triode VT3 links; the collector electrode of triode VT4 is through diode VD2; resistance R 16 links with amplifier IC3; the output of amplifier IC3 connects electronic switching circuit through resistance R 19, its resistance R 17; R18 and capacitor C 7 are the peripheral cell of amplifier IC3.Protective circuit also comprises leakage protection circuit; it is made up of resistance R 20-R23, capacitor C 8, C9, diode VD3, VD4 and operational amplifier IC5; resistance R 20 is connected in series the two ends, back and accesses the input of sample circuit and the input of amplifier IC5 respectively with diode VD4; the output of amplifier IC5 links through resistance R 23 and electronic switching circuit, and resistance R 21, R22 and capacitor C 9 are the peripheral cell of amplifier IC5.

Overvoltage sample circuit and overvoltage crowbar are made up of following device respectively: the overvoltage sample circuit is made up of the rectification circuit that transformer T3 and diode VD5-VD8 form; Overvoltage crowbar is made up of resistance R 24-R29, capacitor C 10, voltage stabilizing didoe DW3 and operational amplifier IC6; resistance R 27 is connected in series back and diode DW3 and the output of taking over the pressure sample circuit after resistance R 26 is connected in series respectively with resistance R 28; its the two mid point connects the input of amplifier IC6 respectively, and the output of amplifier IC6 connects electronic switching circuit through resistance R 29.

Electronic switching circuit is made up of resistance R 1, R2, triode VT1, VT2, diode VD1 and bidirectional triode thyristor, triode VT1 is compound the connection with triode VT2, it is by the base stage incoming control signal of triode VT2, the emitter of triode VT1 links through the control end of diode VD1 and controllable silicon VS, and controllable silicon VS is serially connected with in the ac circuit.

The technological progress that the utility model is obtained is: this device utilizes the control of low-voltage direct electronic component realization to the AC power frequency circuit; adopt the contactless electronic beam switch circuit; make its operate time of protection can in 3 microseconds-0.01 second, cut off the ac circuit of controlling reliably; avoid the intensification of alternating current circuit or caught fire, prevented the generation and the diffusion of accident effectively.This device can effectively protect the faults such as short circuit, virtual connection, overload flow, overvoltage and electric leakage that take place in the ac circuit simultaneously; it is very little to make it short circuit no-spark or spark; virtual connection, electric leakage, overvoltage, overcurrent do not burn line and do not strike sparks; avoided the generation and the diffusion of electrical fire and explosion accident, realized effective protection of power consumption equipment and ensured the safety of people's lives and properties.

Be that embodiment further describes the utility model below with the accompanying drawing:

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

Fig. 2 is an electrical schematic diagram of the present utility model.

As shown in Figure 1; electronic switching circuit, sample circuit A, B and load are serially connected with in the ac circuit simultaneously; the overvoltage sampling loop is connected in the ac circuit; between sample circuit and electronic switching circuit respectively and be connected to short-circuit protection circuit, overload protecting circuit, virtual connection protective circuit, leakage protection circuit and overvoltage crowbar; when ac circuit breaks down; sample circuit will send corresponding abnormal signal and give protective circuit; protective circuit provides a control signal for electronic switching circuit; make electronic switch move, promptly cut off ac main circuit.The operation principle of its each several part is as follows, will describe respectively:

As shown in Figure 2, when ac circuit is short-circuited fault, produce a surge current in moment in the ac circuit, sample circuit A forms by resistance R 0, instrument transformer T1 with by the bridge rectifier that diode VD2-VD2 constitutes.Surge current produces a big voltage drop at the primary coil two ends of resistance R 0 and instrument transformer T1, the rectifier bridge U that is made of diode VD2-VD5 exports a direct current signal, input to 5 pin of operational amplifier IC1 through resistance R 3 and voltage stabilizing didoe DW1, this moment, the 5 pin current potentials of IC1 were higher than 6 pin current potentials, 7 pin of IC1 will be exported a high potential, this high potential provides the base stage operating voltage for triode VT2 through resistance R 6, make the VT2 conducting, approximate short circuit between the collector electrode of VT2 and emitter at this moment, make the base voltage of triode VT1 be approximately zero, promptly VT1 ends.Ending of VT1 will be cut to the Control current that electronic switch VS control end (bidirectional triode thyristor) provides, and make controllable silicon VS end, and promptly the AC load loop is cut off, and accident is by choke suppress.Resistance R 4, R5 and capacitor C 1 are the peripheral cell of IC1; wherein the effect of resistance R 4 is when the 7 pin output high potential of IC1; make 6 pin of IC1 keep high potential simultaneously; thereby make IC1 be in the lock-out state of high potential output; guaranteed that promptly controllable silicon VS continues to be in the state of shutoff; can avoid the recurrence of accident, the protection after the fault that realized being short-circuited.

In when, in the ac circuit overload fault taking place when, overload protecting circuit work, overload protecting circuit is made up of operational amplifier IC2, resistance R 9-R11, capacitor C 2, C3 and voltage stabilizing didoe DW2.The operation principle of its this part and circuit structure are identical with the operation principle of above-mentioned short-circuit protection circuit; difference only is when load current surpasses rated current 10%; high potential signal of overload protecting circuit output turn-offs controllable silicon VS, promptly cuts off the AC load loop.

When virtual connection sparking fault takes place in the ac circuit, the electric current in the load circuit will take place greatly-little-big-little repetitive process, also have the high frequency waves association simultaneously.The virtual connection protective circuit is made up of resistance R 13-R19, capacitor C 4-C7, triode VT3-VT3, diode VD2 and operational amplifier IC.Sample circuit A will export the pulse signal of a high frequency, pulse signal provides operating voltage through capacitor C 5 and resistance R 14 for the base stage of triode VT5, the VT5 conducting, make triode VT4 conducting simultaneously, provide a high potential through diode VD2 and resistance R 16 for the positive input terminal of operational amplifier IC3 by the collector electrode of VT4, make IC3 provide a high potential signal for electronic switching circuit, promptly turn-off controllable silicon VS, cut off the AC load loop through resistance R 19.The pulse signal of sample circuit A output simultaneously is added to the base stage of triode VT3 through capacitor C 4 and resistance R 12, makes VT3 end, thereby more effectively guarantees the conducting of triode VT4.

The earth leakage protective of ac circuit is realized by sample circuit B and leakage protection circuit.Sample circuit B is made up of zero-sequence transformer T2 and operational amplifier IC4.Leakage protection circuit is made of resistance R 20-R23, capacitor C 8, C9, diode VD3, VD4 and operational amplifier IC5.In when, in the ac circuit leak current fault taking place when, the Shen is connected to the electric current that is flow through among the primary winding L1 of zero-sequence transformer T2 in the ac circuit and the L2 and produces difference (under normal circumstances the size of current that flows through among L1 and the L2 equates, direction is opposite, and promptly the resultant flux amount is zero; The influence electricity miscarriage is given birth among the L3), making has induced current to produce among the secondary coil L3 of T2,3 pin of operational amplifier IC4 obtain a current potential that is higher than 2 pin, by high potential of its 5 pin output, this high potential is input to the positive input terminal of operational amplifier IC5 through resistance R 20 and diode VD4, make the control signal of a high potential of IC5 output give electronic switching circuit, promptly turn-off controllable silicon VS, cut off the AC load loop through resistance R 23.

The overvoltage protection of ac circuit is realized by overvoltage sample circuit and overvoltage crowbar.The overvoltage sample circuit is formed by power transformer T3 with by the bridge rectifier that diode VD6-VD9 constitutes.Overvoltage crowbar is made up of resistance R 24-R29, capacitor C 10, voltage stabilizing didoe DW3 and operational amplifier IC6.When the overvoltage fault appears in ac circuit, the primary voltage that is connected to the power transformer T3 in the ac circuit raises, the output voltage of bridge rectifier increases, make IC6 two inputs produce difference signal, IC6 exports a high potential control signal, this control signal is promptly turn-offed controllable silicon VS, cuts off the AC load loop.

The model of employed operational amplifier IC1-IC3, IC5, IC6 is LM324 * 2 in the foregoing circuit, and wherein each amplifier negative terminal input signal A0 is provided by overvoltage crowbar.The model of IC4 is LM386.Protective circuit was started working when the resistance R in the overload protecting circuit 8 was used for the regulating load electric current and surpasses the much amplitude of rated current in addition, and present embodiment is selected for use and surpassed specified 10% o'clock protective circuit and start.R28 effect in the overvoltage crowbar is similar with R8.

Claims

1, a kind of ac circuit flameproof protection device is characterized in that it comprises electronic switching circuit, sample circuit and the load that is serially connected with in the ac circuit, and the output of its sample circuit connects electronic switching circuit through protective circuit.

2, protective device according to claim 1; it is characterized in that also connecting in the ac circuit overvoltage sample circuit and reach the overvoltage crowbar that links with the overvoltage sample circuit; the input of overvoltage sample circuit is connected in the ac circuit, and its output connects electronic switching circuit through overvoltage crowbar.

3, protective device according to claim 1 and 2, it is characterized in that said sample circuit is made up of sample circuit A and sample circuit B, described sample circuit A is made up of instrument transformer T1, resistance R 0 and rectifier bridge U, the elementary winding of its resistance R 0 and instrument transformer T1 and connect after be serially connected with in the ac circuit, the secondary winding of instrument transformer T1 connects the input of rectifier bridge U; Said sample circuit B is made up of instrument transformer T2 and amplifier IC4, and the two elementary winding L 1 of its instrument transformer T2, L2 are serially connected with respectively in the ac circuit, the secondary input that meets amplifier IC4 of instrument transformer T2.

4, protective device according to claim 1 is characterized in that described protective circuit comprises short-circuit protection circuit, overload protecting circuit and virtual connection protective circuit, and its three also connects between back access sample circuit and electronic switching circuit.

5, protective device according to claim 4; it is characterized in that said short-circuit protection circuit is made up of resistance R 3-R6, capacitor C 1, voltage stabilizing didoe DW1 and operational amplifier IC1; resistance R 3 is connected in series the two ends, back and accesses the output of sample circuit and the input of amplifier IC1 respectively with diode DW1; its resistance R 4-R6 and capacitor C 1 are the peripheral cell of amplifier IC1, and the output of amplifier IC1 connects electronic switching circuit through resistance R 6.

6, protective device according to claim 4; it is characterized in that said overload protecting circuit is made up of resistance R 7-R11, capacitor C 2, C3, voltage stabilizing didoe DW2 and operational amplifier IC2; its resistance R 7, R8 are connected in series the two ends, back and access the output of sample circuit and the input of amplifier IC2 respectively with diode DW2, its resistance R 9-R11 and resistance C3 are the peripheral cell of amplifier IC2.

7; protective device according to claim 4; it is characterized in that said virtual connection protective circuit is by resistance R 12-R19; capacitor C 4-C7; diode VD2; triode VT3-VT5 and operational amplifier IC3 form; the base stage of triode VT3 and VT5 is respectively through resistance R 12; capacitor C 4 and resistance R 14; access the output of sample circuit after the capacitor C 5; the base stage of triode VT4 links through the collector electrode of resistance R 15 with triode VT5; the collector electrode of the emitter of triode VT4 and triode VT3 links; the collector electrode of triode VT4 is through diode VD2; resistance R 16 links with amplifier IC3; the output of amplifier IC3 connects electronic switching circuit through resistance R 19, its resistance R 17; R18 and capacitor C 7 are the peripheral cell of amplifier IC3.

8, protective device according to claim 4; it is characterized in that said protective circuit also comprises leakage protection circuit; it is made up of resistance R 20-R23, capacitor C 8, C9, diode VD3, VD4 and operational amplifier IC5; resistance R 20 is connected in series the two ends, back and accesses the input of sample circuit and the input of amplifier IC5 respectively with diode VD4; the output of amplifier IC5 links through resistance R 23 and electronic switching circuit, and resistance R 21, R22 and capacitor C 9 are the peripheral cell of amplifier IC5.

9, protective device according to claim 2, it is characterized in that said overvoltage sample circuit and overvoltage crowbar be made up of following device respectively: the overvoltage sample circuit is made up of the rectification circuit that transformer T3 and diode VD5-VD8 form; Overvoltage crowbar is made up of resistance R 24-R29, capacitor C 10, voltage stabilizing didoe DW3 and operational amplifier IC6; resistance R 27 is connected in series back and diode DW3 and the output of taking over the pressure sample circuit after resistance R 26 is connected in series respectively with resistance R 28; its the two mid point connects the input of amplifier IC6 respectively, and the output of amplifier IC6 connects electronic switching circuit through resistance R 29.

10, protective device according to claim 1; it is characterized in that said electronic switching circuit is made up of resistance R 1, R2, triode VT1, VT2, diode VD1 and bidirectional triode thyristor; triode VT1 is compound the connection with triode VT2; it is by the base stage incoming control signal of triode VT2; the emitter of triode VT1 links through the control end of diode VD1 and controllable silicon VS, and controllable silicon VS is serially connected with in the ac circuit.