CN202906435U

CN202906435U - Overcurrent protection circuit

Info

Publication number: CN202906435U
Application number: CN 201220659576
Authority: CN
Inventors: 郭俊浩
Original assignee: TIANSHUI QINGHUA MICROWAVE INSTRUMENT CO Ltd
Current assignee: TIANSHUI QINGHUA MICROWAVE INSTRUMENT CO Ltd
Priority date: 2012-11-20
Filing date: 2012-11-20
Publication date: 2013-04-24
Anticipated expiration: 2022-11-20

Abstract

The utility model discloses an overcurrent protection circuit which can adjust cut-off current value and is high in sensitivity. The overcurrent protection circuit comprises power supply input terminals composed of a first input terminal and a second input terminal, power supply output terminals composed of a first output terminal and a second output terminal, a control switch, and a silicon controlled rectifier. A normally-closed contact of the control switch is connected between the first input terminal and the first output terminal. A potentiometer is connected between the second input terminal and the second output terminal. A rectifier diode and a filtering capacitor are connected between the power supply input terminals. A control coil of the control switch is connected in series with the silicon controlled rectifier and then connected in parallel with the filtering capacitor. A control electrode of the silicon controlled rectifier is connected with a moving contact leading-out terminal of the potentiometer. A reset switch is further connected in parallel between an anode and a cathode of the silicon controlled rectifier.

Description

A kind of current foldback circuit

Technical field

The utility model relates to a kind of protective circuit, relates in particular to a kind of current foldback circuit.

Background technology

The devices such as general circuit breaker, air switch have overcurrent protection function, but mostly are set in rated value, can not regulate, and sensitivity is lower.And need frequent starting, the higher occasion of current protection requirement in the laboratory etc.; need accurately to set cut-off current; and cut-off current can be regulated; when electric current in circuit load or the equipment surpasses the setting cut-off current; protective circuit will thoroughly be cut off power supply, until after the fault eliminating, could continue power supply through manually resetting; can thoroughly avoid because of fire that load overcurrent causes, damage the generation of the secondary disasters such as power consumption equipment, and prior art does not solve the record of the technical scheme of relevant issues.

The utility model content

Technical problem to be solved in the utility model is the deficiency that exists for prior art, and a kind of current foldback circuit is provided, and this circuit can be regulated cut-off current, and highly sensitive.

The utility model the utility model adopts the basic conception of technical scheme to be: a kind of current foldback circuit; comprise by first input end; the power input that the second input forms; by the first output; the power output end that the second output forms; control switch and controllable silicon; first input end; connect the normally closed contact of control switch between the first output; the second input; connect potentiometer between the second output; connect rectifier diode and filter capacitor between the power input; in parallel with filter capacitor behind the control coil of control switch and the controllable silicon in serial connection; the silicon controlled control utmost point connects the moving contact exit of potentiometer, reset switch in parallel also between the controllable silicon anode and cathode.

Preferably, described control switch is relay; Also be parallel with resistance between two terminal exits of described potentiometer.

The beneficial effects of the utility model are, utilize the break-make of the electric current in the control coil of SCR control control switch, thereby the break-make of the normally closed contact of control control switch, realize the break-make of power output end, because the silicon controlled latching characteristics is pressed the reset switch hand-reset and could be continued power supply, improved safety and reliability, because the silicon controlled control utmost point draws the moving contact exit of self-potential device, realized the fine adjustment of cut-off current, highly sensitive.

Description of drawings

Accompanying drawing is circuit theory diagrams of the present utility model.

Among the figure: power input Ui power output end Uo relay J 1 controllable silicon SCR reset switch SBT rectifier diode V1 filter capacitor C1 potentiometer RP1 sample resistance Rb resistance R 1 load R _LCapacitor C 2

Embodiment

As shown in drawings, between power supply first input end, the first output, succeed the normally closed contact of electrical equipment J1, access sample resistance R b between power supply the second input, the second output, sample resistance Rb potentiometer RP1 in parallel, power input Ui connects that rectifier diode V1 carries out halfwave rectifier and filter capacitor C1 carries out filtering, this current rectifying and wave filtering circuit output is connected to the control coil of controllable silicon SCR and relay J 1, controllable silicon SCR anode and cathode two ends reset switch SBT in parallel, the control utmost point of controllable silicon SCR draws the moving contact exit of self-potential device RP1.

As load R _LBecause failure and other reasons, when causing operating current unusually to increase, the upper voltage drop that produces of sample resistance Rb increases thereupon, when voltage surpasses a set point (this set point is regulated by potentiometer RP1), the controllable silicon SCR conducting, the control coil of relay J 1 gets electric, and the normally closed contact of relay J 1 disconnects, load R _LOn just do not had operating voltage, obtained protection, this moment, even do not have do not have sampling voltage on electric current, the sample resistance Rb on the load RL, controllable silicon SCR is continuous firing still, guarantees that circuit does not have output voltage because the latching characteristics of controllable silicon SCR.After fault is got rid of, manually press reset switch SBT, the controllable silicon SCR cut-off that resets, the control coil dead electricity of relay J 1, the normally closed contact closure of relay J 1, power output end Uo obtains electricity, load R _LJust can work on.

Resistance R 1, capacitor C 2 form filter circuit, play Anti-Jamming; Rectifier diode V1, filter capacitor C1 guarantee that circuit can use under exchange status.

Claims

1. current foldback circuit; comprise by first input end; the power input that the second input forms; by the first output; the power output end that the second output forms; control switch and controllable silicon; it is characterized in that; first input end; connect the normally closed contact of control switch between the first output; the second input; connect potentiometer between the second output; connect rectifier diode and filter capacitor between the power input; in parallel with filter capacitor behind the control coil of control switch and the controllable silicon in serial connection; the silicon controlled control utmost point connects the moving contact exit of potentiometer, reset switch in parallel also between the controllable silicon anode and cathode.

2. current foldback circuit according to claim 1 is characterized in that, described control switch is relay.

3, current foldback circuit according to claim 1 and 2 is characterized in that, also is parallel with resistance between two terminal exits of described potentiometer.