CN204967233U - Low temperature rise security residual current operated circuit breaker circuit - Google Patents

Abstract

The low-temperature rise safety residual current operated circuit breaker circuit includes a power supply circuit, a leakage signal acquisition control circuit, a tripping circuit, and a leakage test circuit. The leakage signal acquisition control circuit monitors whether there is a residual current in the main circuit, and when there is a residual current When controlling and driving the tripping circuit to perform a tripping action, the AC input side of the power circuit is connected to the main circuit, and the DC output side of the power circuit is respectively connected to the leakage signal acquisition control circuit and the tripping circuit to provide a DC voltage; The power supply circuit includes a surge absorbing circuit, a half-wave rectifying circuit and a step-down circuit, the input end of the surge absorbing circuit is connected to the main circuit, the output end is connected to the half-wave rectifying circuit, and the output end of the half-wave rectifying circuit is connected to the disconnecting circuit respectively. The buckle circuit is connected with the step-down circuit, and the step-down circuit is connected with the leakage signal acquisition control circuit. The invention has the beneficial effects of low temperature of the dropping resistor, strong anti-surge capability and low cost.

Description

Low temperature rise safety residual current operated circuit breaker circuit

technical field

The utility model belongs to the field of low-voltage electrical appliances, and relates to a residual current operating circuit breaker with overcurrent protection, in particular to a circuit of the residual current operating circuit breaker with overcurrent protection.

Background technique

At present, the power circuit of this type of circuit breaker generally adopts the form of full-wave rectification, resistance-capacitance step-down or resistance step-down, in which the voltage after full-wave rectification is relatively high, and the full-wave rectification circuit uses four rectifier diodes, which is very important for electronic component boards. The cost and miniaturization of the resistor bring many disadvantages; while the temperature of the resistance step-down circuit rises during operation, which affects the reliability of the circuit and the service life of the components; although the temperature rise of the resistance-capacity step-down circuit is low during operation, the cost is high . At the same time, the products on the market have low ability to resist lightning surges, generally cannot withstand 4KV surge impacts, and cannot meet the basic needs of users for product reliability and safety.

Utility model content

In order to overcome the defects of the prior art, the purpose of this utility model is to provide a low temperature rising safety residual current operated circuit breaker circuit with low voltage drop resistor, strong anti-surge capability, low cost, high performance and few components.

In order to achieve the above object, the utility model adopts the following technical solutions:

A low-temperature rising safety residual current operated circuit breaker circuit, including a power supply circuit, a leakage signal acquisition control circuit connected to the secondary coil of a zero-sequence transformer TA, a tripping circuit, and a tripping action for generating an analog detection circuit breaker Whether the residual current leakage test circuit is effective, the leakage signal acquisition control circuit monitors whether there is residual current in the main circuit, and controls and drives the tripping circuit to perform a tripping action when the residual current occurs, and the power supply circuit The AC input side of the power supply circuit is connected with the main circuit, and the DC output side of the power supply circuit is respectively connected with the leakage signal acquisition control circuit and the tripping circuit to provide a DC voltage; the power supply circuit includes a surge absorption circuit, a half-wave rectification circuit and a step-down circuit , the input end of the surge absorption circuit is connected to the main circuit, the output end is connected to the half-wave rectification circuit, the output end of the half-wave rectification circuit is respectively connected to the tripping circuit and the step-down circuit, and the step-down circuit is connected to the leakage signal acquisition control circuit .

Preferably, the step-down circuit of the power supply circuit includes a capacitor C8 connected to the neutral line N at one end and a chip resistor module composed of a plurality of chip resistors, one end of the chip resistor module is connected to The other end of the capacitor C8 is connected to form a DC control output node for controlling leakage tripping protection. This node is connected to the leakage signal acquisition control circuit, and the other end of the chip resistance module is connected to the tripping circuit. .

Preferably, the surge absorbing circuit of the power supply circuit includes a varistor RV1, which is connected in parallel between the live line L and the neutral line N on the AC input side of the power supply circuit.

Preferably, the half-wave rectification circuit of the power supply circuit includes a diode VD1, the anode of the diode VD1 is connected to the live wire L on the AC input side of the power supply circuit, and the cathode of the diode VD1 is connected to the chip resistor of the step-down circuit The other end of the module is connected and connected in parallel with the anode of the thyristor VT1 of the tripping circuit.

Preferably, the chip resistor module of the step-down circuit is composed of multiple chip resistors connected in series.

Preferably, the chip resistor module of the step-down circuit is composed of multiple series chip resistor groups connected in parallel.

Preferably, the chip resistor module of the step-down circuit is composed of multiple parallel chip resistor groups connected in series.

Preferably, the chip resistor module includes a first series chip resistor group composed of chip resistor R5, chip resistor R6, chip resistor R7 and chip resistor R8 connected in series, and chip resistor R9, chip resistor The chip resistor R10, the chip resistor R11 and the chip resistor R12 are connected in series to form a second series chip resistor group, and the first series chip resistor group is connected in parallel with the second series chip resistor group.

Preferably, the chip resistor module includes a first parallel chip resistor group composed of a chip resistor R5 and a chip resistor R6 connected in parallel, a second parallel chip resistor group composed of a chip resistor R7 and a chip resistor R8 connected in parallel. chip resistor group, the third parallel chip resistor group composed of chip resistor R9 and chip resistor R10 in parallel, and the fourth parallel chip resistor group composed of chip resistor R11 and chip resistor R12 in parallel, the first The first parallel chip resistor group, the second parallel chip resistor group, the third parallel chip resistor group and the fourth parallel chip resistor group are sequentially connected in series.

Preferably, the leakage signal acquisition control circuit includes a bidirectional diode D1, a debugging resistor R1, a resistor R2, a resistor R3 and a capacitor C1, a capacitor C2, a capacitor C3, a capacitor C4, a capacitor C5, a capacitor C6, a capacitor C7, a control chip and Zero-sequence transformer TA; debugging resistor R1, bidirectional diode D1, and capacitor C1 are sequentially connected in parallel at both ends of the secondary circuit lead of zero-sequence transformer TA; one end of resistor R2 is connected to one end of capacitor C1, and the other end of resistor R2 One end of capacitor C2, one end of capacitor C3 and the first pin 1 of the control chip are connected in parallel; one end of resistor R3 is connected to the other end of capacitor C1, the other end of resistor R3 is connected to the other end of capacitor C2, and the other end of capacitor C4 One end is connected in parallel with the second pin 2 of the control chip; the other end of the capacitor C3 is connected in parallel with the other end of the capacitor C4 and the third pin 3 of the control chip; one end of the capacitor C5 is connected with the fourth pin 4 of the control chip and The fifth pin 5 is connected in parallel, the other end of the capacitor C5 is grounded; one end of the capacitor C6 is connected to the sixth pin 6 of the control chip, the other end of the capacitor C6 is connected to the seventh pin 7 of the control chip, one end of the capacitor C7 and The G poles of the thyristor VT1 of the tripping circuit are connected in parallel, and the other end of the capacitor C7 is grounded; the eighth pin 8 of the control chip is connected with the DC control output node of the power circuit.

The beneficial effects of the utility model include: due to the structure of the power supply circuit composed of the surge absorbing circuit, the half-wave rectifier circuit and the step-down circuit, and the structure of the step-down circuit adopting a chip resistance module, and through the leakage signal acquisition control circuit The reasonable combination of tripping circuit and leakage test circuit can greatly reduce the step-down burden of the step-down circuit and the temperature rise of the circuit, effectively reduce the volume of the circuit and simplify and optimize the structure of the circuit, and expand and improve the ability to withstand surge shocks The ability to effectively improve the reliability and safety level of products while reasonably reducing production costs.

Description of drawings

Fig. 1 is a structural block diagram of the circuit of the low-temperature rise safety residual current operated circuit breaker of the present invention.

Fig. 2 is a schematic diagram of the circuit structure of the first embodiment of the first embodiment of the chip resistance module of the step-down circuit of the low-temperature rise safety residual current operated circuit breaker circuit of the present invention.

Fig. 3 is a schematic diagram of the circuit structure of the second embodiment of the first embodiment of the chip resistance module of the step-down circuit of the low-temperature rising safety residual current operated circuit breaker circuit of the present invention.

Fig. 4 is a schematic diagram of the circuit structure of the second embodiment of the chip resistance module of the step-down circuit of the low-temperature rise safety residual current operated circuit breaker circuit of the present invention.

Fig. 5 is a schematic diagram of the circuit structure of the third embodiment of the chip resistance module of the step-down circuit of the low-temperature rising safety residual current operated circuit breaker circuit of the present invention.

detailed description

The specific implementation of the low-temperature rise safety residual current operated circuit breaker circuit of the present utility model is further described below in conjunction with the embodiments given in accompanying drawings 1 to 5 .

Referring to the structural block diagram of Fig. 1, the low-temperature rising safety residual current operated circuit breaker of the utility model includes a leakage signal acquisition control circuit, a tripping circuit, a leakage test circuit and a power supply circuit, and the leakage signal acquisition control circuit of the circuit breaker is used for monitoring diagram Whether there is a residual current in the main circuit (L-L1, N-N1) shown in 5, and when the residual current occurs, the tripping circuit is controlled to drive the actuator (tripping coil KA) to perform the tripping action; the leakage test circuit is used to generate Simulate the residual current to detect whether the tripping action of the residual current operated circuit breaker is effective. The utility model is characterized in that the power supply circuit includes a surge absorbing circuit, a half-wave rectifier circuit and a step-down circuit, the input end of the surge absorbing circuit is connected to the main circuit, the output end is connected to the half-wave rectifier circuit, and the output end They are respectively connected to the tripping circuit and the step-down circuit. The step-down circuit is connected to the leakage signal acquisition control circuit. surge protection function. The power supply circuit takes AC power from the main circuit L-L1, N-N1, that is: the live wire L on the AC input side of the power circuit is connected to the live wire phase L-L1 of the main circuit, and the neutral wire on the AC input side of the power circuit N is connected to the neutral line phase (N-N1) of the input main circuit, the positive pole of the DC output side of the power circuit is used to provide DC voltage to the leakage signal acquisition control circuit and the tripping circuit, and the ground pole of the DC output side of the power circuit ( It is also the common ground pole of the power supply circuit of the residual operation circuit breaker) connected to the neutral line N.

The half-wave rectifier circuit of the utility model includes a diode VD1, the anode of the diode VD1 is connected to the live line L on the AC input side of the power circuit, the cathode of the diode VD1 is connected to one end of the chip resistance group, and the thyristor VT1 of the tripping circuit. The anodes are connected in parallel. The advantage of the half-wave rectifier circuit using the diode VD1 is that the structure is simple, and the DC output voltage is low (about 0.45 times the AC input voltage), so it can greatly reduce the step-down burden of the step-down circuit. The resistance module provides the realization possibility, especially the half-wave rectification circuit of the present invention adopts the structure combination of the diode VD1 and the step-down circuit adopts the patch type resistance module, which not only can effectively reduce the temperature rise, but also is very beneficial to the miniaturization of the circuit. It can effectively improve the reliability and safety level of the product.

Another beneficial feature of the utility model is that the step-down circuit of the power supply circuit adopts a chip resistor module, and the step-down circuit includes a capacitor C8 and a chip resistor composed of a plurality of chip resistors such as R5 to R12. Chip resistor module, one end of the chip resistor module is connected to one end of capacitor C8 to form a DC control output node for controlling leakage tripping protection, and this node is connected to the eighth pin 8 of the control chip of the leakage signal acquisition control circuit Connection, the other end of the chip resistor module is connected in parallel with the cathode of the diode VD1 of the half-wave rectifier circuit and the anode of the thyristor VT1 of the tripping circuit, and the other end of the capacitor C8 is grounded. The specific structure of the chip resistor module can be in many ways. Figures 2 and 3 both show the first implementation mode adopted by the chip resistor module of the step-down circuit, and they respectively represent two different connection modes. One end of the tripping coil KA of the tripping circuit in Figure 2 is connected in parallel with one end of the varistor RV1 of the surge absorbing circuit and the live line L of the AC input side of the power circuit, and the other end of the tripping coil KA is connected with the half-wave rectifier circuit Anode connection of diode VD1. In Figure 3, one end of the tripping coil KA is connected in parallel with the other end of the varistor RV1 of the surge absorbing circuit and the neutral line N on the AC input side of the power circuit, and the other end of the tripping coil KA is connected in parallel with the tripping circuit. K pole connection of thyristor VT1. Figures 4 and 5 show the second and third implementations of the chip resistor module. The advantage of the chip resistor module composed of multiple chip resistors is that it can double the voltage and temperature rise of each chip resistor; Parallel connection) or parallel series (as shown in Figure 5, parallel connection first and then series connection) can prevent the product from not operating due to the failure of one of the resistors, thereby improving the reliability and safety of the product.

Specifically, the first method is shown in the embodiment shown in Figure 2 and Figure 3: the chip resistor module of the step-down circuit is composed of multiple series chip resistor groups connected in parallel, the step-down circuit The chip resistor module is composed of two series chip resistor groups connected in parallel, wherein the first series chip resistor group is composed of chip resistor R5, chip resistor R6, chip resistor R7 and chip resistor R8 in series, and the second chip resistor group is connected in series. The two series chip resistor groups are composed of chip resistor R9, chip resistor R10, chip resistor R11 and chip resistor R12 connected in series. The second method is shown in Figure 4: the chip resistor module of the step-down circuit is composed of a plurality of chip resistors connected in series, and these chip resistors include chip resistor R5, chip resistor R6, chip resistor R7, chip resistor R8, chip resistor R9, chip resistor R10, chip resistor R11 and chip resistor R12. The third method is shown in Figure 5: the chip resistor module of the step-down circuit is composed of a plurality of parallel chip resistor groups connected in series, wherein the first parallel chip resistor group consists of chip resistor R5 and resistor R6 Chips are connected in parallel, the second parallel chip resistor group is composed of chip resistor R7 and chip resistor R8 in parallel, the third parallel chip resistor group is composed of chip resistor R9 and chip resistor R10 in parallel, the fourth parallel chip resistor The resistance group is composed of chip resistor R11 and chip resistor R12 connected in parallel. Three specific structural optimizations of the chip resistor module can be summarized as follows: the chip resistor module of the step-down circuit is composed of a plurality of chip resistors connected in series; or, the chip resistor module of the step-down circuit The resistor module is composed of a plurality of chip resistor groups connected in parallel; or, the chip resistor module of the step-down circuit is composed of a plurality of chip resistor groups connected in series.

Another beneficial feature of the utility model is the use of a surge absorbing circuit, that is: the surge absorbing circuit includes a piezoresistor RV1, which is connected in parallel to the live wire L and the neutral wire N on the AC input side of the power circuit Between, that is: one end of the varistor RV1 is connected to the live line L, and the other end of the varistor RV1 is connected to the neutral line N. Since the live wire L and the neutral wire N are respectively connected to the live wire phase (L-L1) and the neutral wire phase (N-N1) of the main circuit, the surge absorption function of the varistor RV1 can not only protect the low temperature rise safety residual Current operated circuit breaker circuit, but also can effectively protect the circuit downstream of the circuit breaker. Due to the use of the surge absorbing circuit and the matching patch resistor module, the ability to withstand surge impact is greatly enhanced, and it can withstand the 4KV surge voltage that the existing ordinary products cannot bear.

The leakage signal acquisition control circuit of the circuit breaker includes bidirectional diode D1, debugging resistor R1, resistor R2, resistor R3 and capacitor C1, capacitor C2, capacitor C3, capacitor C4, capacitor C5, capacitor C6, capacitor C7, control chip and zero-sequence mutual inductance TA; debugging resistor R1, bidirectional diode D1, and capacitor C1 are connected in parallel to both ends of the secondary circuit lead of zero-sequence transformer TA; one end of resistor R2 is connected to one end of capacitor C1, and the other end of resistor R2 is connected to capacitor C2 One end of the capacitor C3 is connected in parallel with the first pin 1 of the control chip; one end of the resistor R3 is connected to the other end of the capacitor C1, the other end of the resistor R3 is connected to the other end of the capacitor C2, and one end of the capacitor C4 is connected to the control chip. The second pin 2 of the chip is connected in parallel; the other end of the capacitor C3 is connected to the other end of the capacitor C4 and the third pin 3 of the control chip; one end of the capacitor C5 is connected to the fourth pin 4 and the fifth pin of the control chip Pin 5 is connected in parallel, the other end of capacitor C5 is grounded; one end of capacitor C6 is connected to the sixth pin 6 of the control chip, the other end of capacitor C6 is connected to the seventh pin 7 of the control chip, one end of capacitor C7 and tripping The G pole (control pole) of the thyristor VT1 of the circuit is connected in parallel, the other end of the capacitor C7 is grounded, the eighth pin 8 of the control chip is connected to the DC control output node of the power supply circuit (that is, the chip resistor of the step-down circuit One end of the module is connected to one end of the capacitor C8 to form a DC control output node (DC control output node) for controlling leakage tripping protection. The control chip adopts electronic devices on the market.

The tripping circuit of the circuit breaker includes the tripping coil KA, the diode VD1 and the thyristor VT1; the G pole (control pole) of the thyristor VT1 is connected to the seventh pin 7 of the control chip, and the A pole (anode) of the thyristor VT1 and the K pole (cathode) of the thyristor VT1 are respectively connected to the live wire L on the AC input side of the power circuit and the neutral wire N on the AC input side to form an on/off control circuit, and the tripping coil KA is connected in series to the on-off / off control circuit. The on/off control circuit has two states of on and off under the control of the G pole of the thyristor VT1; under normal conditions of the main circuit (L-L1, N-N1), the leakage signal acquisition control circuit controls The thyristor VT1 is turned off (making the on/off control circuit in the off state), and the current in the tripping coil KA connected in series in the on/off control circuit cannot excite the tripping coil to generate a tripping action; when the main circuit (L -L1, N-N1) when residual current (leakage current) occurs, the leakage signal acquisition control circuit controls the thyristor VT1 to conduct (trigger on/off control circuit conduction), and the off/off control circuit connected in series The increase of the current in the buckle coil KA, so that the trip coil is excited to generate a tripping action. The specific structure of the tripping circuit can be in many ways. A preferred method is shown in Figure 2, one end of the tripping coil KA of the tripping circuit is connected in parallel with one end of the piezoresistor RV1 of the surge absorbing circuit and the live line L on the AC input side of the power circuit, and the tripping The other end of the buckle coil KA is connected to the anode of the diode VD1 of the half-wave rectifier circuit. Another preferred method is shown in Figure 3, one end of the tripping coil KA is connected in parallel with the other end of the varistor RV1 of the surge absorbing circuit and the neutral line N on the AC input side of the power circuit, The other end of the buckle coil KA is connected to the K pole (cathode) of the thyristor VT1 of the trip circuit. Summarizing the first embodiment and the second embodiment shown in Fig. 2 and Fig. 3, the specific structure of the tripping circuit can be summarized as: the pressure between one end of the tripping coil KA of the tripping circuit and the surge absorbing circuit One end of the sensitive resistor RV1 is connected in parallel with the live wire L on the AC input side of the power circuit, and the other end of the trip coil KA is connected to the anode of the diode VD1 of the half-wave rectifier circuit; or, one end of the trip coil KA is connected to the surge absorbing circuit The other end of the varistor RV1 is connected in parallel with the neutral line N of the AC input side of the power circuit, and the other end of the trip coil KA is connected with the cathode of the thyristor VT1 of the trip circuit.

The test circuit of the circuit breaker includes a normally open test switch S1 and a resistor R4. The normally open test switch S1 and the resistor R4 are connected in series to form a circuit, which is connected in parallel to the live phase (L-L1) of the main circuit after passing through the zero sequence transformer TA Between the neutral phase (N-N1). When the test switch S1 is manually pressed to turn on the test circuit, the current flowing in the test circuit can simulate the residual current, so that the residual current signal will be induced in the secondary circuit of the zero-sequence transformer TA, and the signal can Trigger the tripping coil KA to generate a tripping action, so as to detect whether the tripping protection of the circuit breaker is normal.

The above content is a further detailed description of the utility model in combination with specific preferred embodiments, and it cannot be assumed that the specific implementation of the utility model is only limited to these descriptions. For a person of ordinary skill in the technical field to which the utility model belongs, without departing from the concept of the utility model, some simple deduction or substitutions can also be made, which should be regarded as belonging to the protection scope of the utility model.

Claims (10)

1. A low temperature rising safety residual current operated circuit breaker circuit, comprising a power supply circuit, a leakage signal acquisition control circuit connected to the secondary coil of the zero-sequence transformer TA, a tripping circuit and a tripping circuit for generating analog detection circuit breakers A residual current leakage test circuit for determining whether the tripping action is valid, the leakage signal acquisition control circuit monitors whether there is a residual current in the main circuit, and controls and drives the tripping circuit to perform a tripping action when a residual current occurs, and is characterized in that : The AC input side of the power supply circuit is connected to the main circuit, and the DC output side of the power supply circuit is respectively connected to the leakage signal acquisition control circuit and the tripping circuit to provide a DC voltage; the power supply circuit includes a surge absorbing circuit, a half-wave rectifier Circuit and step-down circuit, the input end of the surge absorbing circuit is connected to the main circuit, the output end is connected to the half-wave rectification circuit, the output end of the half-wave rectification circuit is connected to the tripping circuit and the step-down circuit respectively, and the step-down circuit is connected to the leakage The signal acquisition control circuit is connected. 2. The low temperature rising safety residual current operated circuit breaker circuit according to claim 1, characterized in that: the step-down circuit of the power supply circuit includes a capacitor C8 connected to the neutral line N and a plurality of chip resistors A combined chip resistance module, one end of the chip resistance module is connected to the other end of the capacitor C8 to form a DC control output node for controlling leakage tripping protection, and this node is connected to the leakage signal The acquisition control circuit is connected, and the other end of the chip resistor module is connected to the tripping circuit. 3. The low temperature rising safety residual current operated circuit breaker circuit according to claim 1, characterized in that: the surge absorbing circuit of the power circuit includes a piezoresistor RV1, which is connected in parallel to the AC input side of the power circuit between the live line L and the neutral line N. 4. The low temperature rising safety residual current operated circuit breaker circuit according to claim 2, characterized in that: the half-wave rectification circuit of the power supply circuit includes a diode VD1, and the anode of the diode VD1 communicates with the power supply circuit The live line L on the input side is connected, and the cathode of the diode VD1 is connected to the other end of the chip resistor module of the step-down circuit, and is connected in parallel with the anode of the thyristor VT1 of the tripping circuit. 5 . The low-temperature rising safety residual current operated circuit breaker circuit according to claim 2 , wherein the chip resistor module of the step-down circuit is composed of a plurality of chip resistors connected in series. 6 . 6. The residual current operated circuit breaker circuit according to claim 2, characterized in that: the chip resistor module of the step-down circuit is composed of a plurality of series chip resistor groups connected in parallel. 7. The low-temperature rise safety residual current operated circuit breaker circuit according to claim 2, characterized in that: the chip resistor module of the step-down circuit is composed of a plurality of parallel chip resistor groups connected in series. 8. The low temperature rising safety residual current operated circuit breaker circuit according to claim 6, characterized in that: said chip resistor module includes chip resistor R5, chip resistor R6, chip resistor R7 and chip resistor The first series chip resistor group composed of chip resistor R8 in series and the second series chip resistor group composed of chip resistor R9, chip resistor R10, chip resistor R11 and chip resistor R12 in series, the first series chip resistor group The chip resistor group is connected in parallel with the second series chip resistor group. 9. The low-temperature rise safety residual current operated circuit breaker circuit according to claim 7, characterized in that: said chip resistor module includes a first parallel chip resistor R5 and a chip resistor R6 connected in parallel Chip resistor group, the second parallel chip resistor group composed of chip resistor R7 and chip resistor R8 in parallel, the third parallel chip resistor group composed of chip resistor R9 and chip resistor R10 in parallel, and the chip resistor group composed of The fourth parallel chip resistor group composed of R11 and chip resistor R12 in parallel, the first parallel chip resistor group, the second parallel chip resistor group, the third parallel chip resistor group and the fourth parallel chip resistor group Groups are sequentially connected in series. 10. The low temperature rising safety residual current operated circuit breaker circuit according to claim 1, characterized in that: the leakage signal acquisition control circuit includes a bidirectional diode D1, a debugging resistor R1, a resistor R2, a resistor R3 and a capacitor C1, Capacitor C2, capacitor C3, capacitor C4, capacitor C5, capacitor C6, capacitor C7, control chip and zero-sequence transformer TA; debugging resistor R1, bidirectional diode D1, and capacitor C1 are sequentially connected in parallel to the secondary circuit of zero-sequence transformer TA Two ends of the lead wire; one end of the resistor R2 is connected to one end of the capacitor C1, the other end of the resistor R2 is connected in parallel with one end of the capacitor C2, one end of the capacitor C3 and the first pin of the control chip; one end of the resistor R3 is connected to the capacitor C1 The other end is connected, the other end of the resistor R3 is connected to the other end of the capacitor C2, one end of the capacitor C4 is connected in parallel with the second pin of the control chip; the other end of the capacitor C3 is connected to the other end of the capacitor C4 and the third tube of the control chip The pins are connected to the ground in parallel; one end of the capacitor C5 is connected in parallel with the fourth and fifth pins of the control chip, and the other end of the capacitor C5 is connected to the ground; one end of the capacitor C6 is connected to the sixth pin of the control chip, and the other end of the capacitor C6 It is connected in parallel with the seventh pin of the control chip, one end of capacitor C7 and the G pole of the thyristor VT1 of the trip circuit, and the other end of capacitor C7 is grounded; the eighth pin of the control chip is connected to the DC control output node of the power circuit connect.