CN201975754U - Electric leakage overcurrent protection circuit - Google Patents

Abstract

The utility model relates to a protection circuit for electrical appliance electricity utilization, in particular to an electric leakage overcurrent protection circuit. The protection circuit adopts the following technical scheme; the protection circuit comprises an electric leakage protection circuit and an overcurrent protection circuit, wherein an overcurrent mutual inductor ZCT2 of the overcurrent protection circuit is connected to an alternating current live wire L; the secondary output end is output to the base and the emitter of an audion Q1 successively by a rectifier circuit, a filter circuit, a time delay circuit and a resistance voltage division circuit; the collector of the audion Q1 is connected with the input end of the comparison amplification pin of an electric leakage protection control chip IC1; and the emitter of the audion is earthed. According to the above technical scheme, the protection circuit has the beneficial effect that the delay time of overcurrent tripping action and the overcurrent can be adaptively adjusted at an inverse ratio. The protection circuit is suitable for the overcurrent protection of occasions with electrical appliances of large starting current, such as motors and the like.

Description

The electric leakage current foldback circuit

Technical field

The utility model relates to the protection circuit of electrical equipment electricity consumption, relates in particular to a kind of electric leakage current foldback circuit.

Background technology

The electric leakage current foldback circuit is used to prevent that the live wire accident of its rear end is landed or the human body single line gets an electric shock, and is used for security protection is carried out in the short circuit of its rear end or the unexpected big electric current of electrical appliance.The existing overcurrent protection that is widely used the electric leakage current foldback circuit partly has plenty of the high molecular PTC of employing self-resetting type fuse; has plenty of the general insurance of employing silk; has plenty of the ceramic self-healing fuse of employing; the employing bimetal leaf that has carries out the protection of short circuit or overcurrent; adopt above-mentioned mode weak point to be: for the bigger electrical appliance of start moment starting current as motor one class; the overcurrent protection value of above-mentioned technical scheme if be provided with the bigger rated current that far exceeds electrical appliance; then be unfavorable for overcurrent protection to the general running status of electrical appliance; its overcurrent protection value is if be provided with to such an extent that be applicable to general electrical appliance; then the bigger electrical appliance of starting current as motor one class is difficult to normal startup; that is: the length of the time of delay of the overcurrent tripping action size that can not be inversely proportional to overcurrent is regulated adaptively; make it in the occasion that has as the very big electrical appliance of starting currents such as motor, can not well play the effect of overcurrent protection.

The utility model content

At the deficiency of prior art scheme, the length that the utility model proposes a kind of time of delay of its overcurrent tripping action can be inversely proportional to the electric leakage current foldback circuit that the size of overcurrent is regulated adaptively.

The technical solution adopted in the utility model is as follows:

The electric leakage current foldback circuit; comprise: be connected to the live wire L of alternating current and the zero sequence current mutual inductor ZT1 of zero line N; reference voltage pin input end and side that one of its secondary output is terminated at an earth leakage protective control chip IC1 connect the 3rd capacitor C 3 to ground; the other end one the 4th capacitor C 4 of connecting connects the relatively amplification pin input end of described earth leakage protective control chip IC1; the control output end of described earth leakage protective control chip IC1 is connected in the control utmost point of acontrollable silicon SCR 1; be connected to the current transformer ZCT2 excessively of alternating current fire wire L; this end of crossing the secondary output end of current transformer ZCT2 rectification circuit of connecting successively; one filter circuit; an one time delay circuit and a resistor voltage divider circuit export the base stage of a triode Q1 to; the other end is connected to the emitter of this triode Q1; the collector electrode of this triode Q1 connects the relatively amplification pin input end of described earth leakage protective control chip IC1; its emitter is connected to the grounding pin of described earth leakage protective control chip IC1; be connected on the above-mentioned live wire L behind the coil TK1 of a release of describedcontrollable silicon SCR 1 series connection; described release K1 is serially connected with respectively on the live wire L and zero line N incoming line of alternating current, and controls break-make by the coil TK1 of release.

Further, described rectification circuit is to be made of the end that rectifier diode D3 was series at the secondary output of current transformer ZCT2.

Further, described filter circuit is a capacitor filter, and its input is connected to the output of described rectification circuit.

Further, described time delay circuit is a RC time delay circuit, wherein, an end ground connection of the 5th capacitor C 5, the other end is connected and is connect the output of described rectification circuit and the input of described resistor voltage divider circuit after the7th resistance R 7.

Further; described resistor voltage divider circuit comprises the 8th resistance R 8 and the 9th resistance R 9 of series connection; the 8th resistance R 8 of this series connection and the 9th resistance R 9 are connected to the output of described time delay circuit, the base stage of the described overcurrent protection triode of the middle termination Q1 of the 8th resistance R 8 and the 9th resistance R 9.

Further, described earth leakage protective control chip IC1 is the FM2140 chip.

Further, a described zero sequence current mutual inductor ZCT1 secondary output end resistance R 5 in parallel; The described current transformer ZCT2 secondary output end resistance R 6 in parallel of crossing.

Further, also connect a piezo-resistance MOV between described live wire L and the zero line N.

Further, described live wire L also connects polarity diode D1, a current-limiting resistance R2 andLED 1 to zero line N.

The utility model is by adopting technique scheme, and the beneficial effect that has is:

1. the input that makes full use of earth leakage protective control chip IC1 carries out the triggering that overcurrent protection is threaded off and moved, and trigger action is more reliable;

2. the length of the time of delay of the overcurrent tripping action size that can be inversely proportional to overcurrent is regulated adaptively, applicable to the overcurrent protection that has as the very big occasions such as electrical appliance of starting currents such as motor.

Description of drawings

Fig. 1 is the circuit theory diagrams of the utility model one embodiment.

Embodiment

Now in conjunction with the accompanyingdrawings 1 and embodiment the utility model is further specified.

The electric leakage current foldback circuit; comprise: be connected to the live wire L of alternating current and the zero sequence current mutual inductor ZT1 of zero line N; reference voltage pin input end and side that one of its secondary output is terminated at an earth leakage protective control chip IC1 connect the 3rd capacitor C 3 to ground; the other end one the 4th capacitor C 4 of connecting connects the relatively amplification pin input end of described earth leakage protective control chip IC1; the control output end of described earth leakage protective control chip IC1 is connected in the control utmost point of acontrollable silicon SCR 1; be connected to the current transformer ZCT2 excessively of alternating current fire wire L; this end of crossing the secondary output end of current transformer ZCT2 rectification circuit of connecting successively; one filter circuit; an one time delay circuit and a resistor voltage divider circuit export the base stage of a triode Q1 to; the other end is connected to the emitter of this triode Q1; the collector electrode of this triode Q1 connects the relatively amplification pin input end of described earth leakage protective control chip IC1; its emitter is connected to the grounding pin of described earth leakage protective control chip IC1; be connected on the above-mentioned live wire L behind the coil TK1 of a release of describedcontrollable silicon SCR 1 series connection; described release K1 is serially connected with respectively on the live wire L and zero line N incoming line of alternating current, and controls break-make by the coil TK1 of release.

As one preferred embodiment, described rectification circuit is to be made of the end that rectifier diode D3 was series at the secondary output of current transformer ZCT2.

As one preferred embodiment, described filter circuit is a capacitor filter, and its input is connected to the output of described rectification circuit.

As one preferred embodiment, described time delay circuit is a RC time delay circuit, wherein, an end ground connection of the 5th capacitor C 5, the other end is connected and is connect the output of described rectification circuit and the input of described resistor voltage divider circuit after the7th resistance R 7.

As one preferred embodiment; described resistor voltage divider circuit comprises the 8th resistance R 8 and the 9th resistance R 9 of series connection; the 8th resistance R 8 of this series connection and the 9th resistance R 9 are connected to the output of described time delay circuit, the base stage of the described overcurrent protection triode of the middle termination Q1 of the 8th resistance R 8 and the 9th resistance R 9.

As one preferred embodiment, described earth leakage protective control chip IC1 is the FM2140 chip.

As one preferred embodiment, a described zero sequence current mutual inductor ZCT1 secondary output end resistance R 5 in parallel; The described current transformer ZCT2 secondary output end resistance R 6 in parallel of crossing.

As one preferred embodiment, also connect a piezo-resistance MOV between described live wire L and the zero line N.

As one preferred embodiment, described live wire L also connects polarity diode D1, a current-limiting resistance R2 andLED 1 to zero line N.

By above-mentioned the technical solution of the utility model; when the bigger electrical appliance of the starting current of the output of the zero line N of live wire L such as heavy duty motor and so in a period of time after connection; though its starting current is than big several times of its rated operational current; cross current transformer ZCT2 and induce bigger electromotive force; but the electrochemical capacitor C6 that is connected to the capacitor filter of the secondary output end of crossing current transformer ZCT2 after the rectification can absorb its stronger induced current; RC time delay circuit R7; C5 is slow boosted voltage in the process of charging; be unlikely to cause overcurrent protection triode Q1 can be at this moment between the section conducting; trigger earth leakage protective control chip IC1 and then trigger the release dropout; and when the charging voltage of electrochemical capacitor reaches trigger voltage; can trigger again and cause release to be threaded off; therefore; by regulating the R7 resistance sizes; can adjust the overcurrent trigger delay time; and then make this electric leakage current foldback circuit in the occasion that has as the very big electrical appliance of starting currents such as motor, also can be good at playing the effect of overcurrent protection.

Although specifically show and introduced the utility model in conjunction with preferred embodiment; but the those skilled in the art should be understood that; in the spirit and scope of the present utility model that do not break away from appended claims and limited; can make various variations to the utility model in the form and details, be protection range of the present utility model.

Claims (9)

1. electric leakage current foldback circuit; it is characterized in that; comprise: be connected to the live wire (L) of alternating current and a zero sequence current mutual inductor (ZT1) of zero line (N); reference voltage pin input end and side that one of its secondary output is terminated at an earth leakage protective control chip (IC1) connect the 3rd electric capacity (C3) to ground; the other end one the 4th electric capacity (C4) of connecting connects the relatively amplification pin input end of described earth leakage protective control chip (IC1); the control output end of described earth leakage protective control chip (IC1) is connected in the control utmost point of a controllable silicon (SCR1); be connected to the current transformer (ZCT2) excessively of alternating current fire wire (L); this end of crossing the secondary output end of current transformer (ZCT2) rectification circuit of connecting successively; one filter circuit; an one time delay circuit and a resistor voltage divider circuit export the base stage of a triode (Q1) to; the other end is connected to the emitter of this triode (Q1); the collector electrode of this triode (Q1) connects the relatively amplification pin input end of described earth leakage protective control chip (IC1); its emitter is connected to the grounding pin of described earth leakage protective control chip (IC1); be connected on the above-mentioned live wire (L) behind the coil (TK1) of a release of described controllable silicon (SCR1) series connection; described release (K1) is serially connected with respectively on the live wire (L) and zero line (N) incoming line of alternating current, and controls break-make by the coil (TK1) of release.

2. electric leakage current foldback circuit as claimed in claim 1 is characterized in that: described rectification circuit is the end formation that was series at the secondary output of current transformer (ZCT2) by rectifier diode (D3).

3. electric leakage current foldback circuit as claimed in claim 1 is characterized in that: described filter circuit is a capacitor filter, and its input is connected to the output of described rectification circuit.

4. electric leakage current foldback circuit as claimed in claim 1; it is characterized in that: described time delay circuit is a RC time delay circuit; wherein; one end ground connection of the 5th electric capacity (C5), the other end the 7th resistance (R7) of connecting connects the output of described rectification circuit and the input of described resistor voltage divider circuit afterwards.

5. electric leakage current foldback circuit as claimed in claim 1; it is characterized in that: described resistor voltage divider circuit comprises the 8th resistance (R8) and the 9th resistance (R9) of series connection; the 8th resistance (R8) of this series connection and the 9th resistance (R9) are connected to the output of described time delay circuit, the base stage of the described overcurrent protection triode of the middle termination Q1 of the 8th resistance (R8) and the 9th resistance (R9).

6. electric leakage current foldback circuit as claimed in claim 1 is characterized in that: described earth leakage protective control chip (IC1) is the FM2140 chip.

7. electric leakage current foldback circuit as claimed in claim 1 is characterized in that: described zero sequence current mutual inductor (ZCT1) secondary output end resistance (R5) in parallel; Described current transformer (ZCT2) the secondary output end resistance (R6) in parallel of crossing.

8. electric leakage current foldback circuit as claimed in claim 1 is characterized in that: also connect a piezo-resistance (MOV) between described live wire (L) and the zero line (N).

9. electric leakage current foldback circuit as claimed in claim 1 is characterized in that: described live wire (L) is also connected a polarity diode (D1), current-limiting resistance (R2) and light-emitting diode (LED1) to zero line (N).

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