CN219107054U - Circuit protection device capable of automatically monitoring operation faults - Google Patents

Abstract

The utility model discloses a circuit protection device for automatically monitoring operation faults, which comprises a ground fault detection circuit, an alternating current power supply channel and an electromagnetic driving circuit, wherein the self-fault detection unit comprises a measurement and control circuit and a fault state holding circuit, the measurement and control circuit starts a self-fault detection process at regular time and monitors fault state signals returned by the electromagnetic driving circuit to realize self-fault detection, if faults occur, an emergency interrupt signal is output to trigger the ground fault protection unit to release emergently, the fault state holding circuit comprises a zero clearing circuit and a fault state triggering circuit, the zero clearing circuit clears the fault state, and the fault state triggering circuit keeps fault state information output by the measurement and control circuit to generate effective warning information so as to improve the reliability of the circuit protection device.

Description

Circuit protection device capable of automatically monitoring operation faults

Technical Field

The application belongs to the technical field of circuit protection, and particularly relates to a circuit protection device capable of automatically monitoring operation faults, in particular to a residual current action protection device or a grounding fault circuit interrupt device.

Background

The residual current action protector or the earthing fault circuit interrupt device is used for detecting the earthing fault current GFC of appliances, instruments, devices, equipment, electrical systems and other power utilization appliances and power supply lines powered by a power grid power supply, and when the earthing fault current GFC exceeds a specified limit value, the circuit protector automatically cuts off the power supply, thereby achieving the aim of protecting personal and property safety. In practical use, the residual current operation protection device or the ground fault detection circuit of the ground fault circuit interrupt device often fails locally or totally, resulting in failure of the protection function of the ground fault circuit interrupt device or loss of warning information, which is not known by the user at this time, and presents a safety hazard.

In order to solve the above problems, some ground fault circuit interrupting devices are designed according to UL943 standard, and a self-fault monitoring function is provided to periodically diagnose the operating condition of the ground fault circuit interrupting device and output a warning signal or trip a protection mechanism thereof when the ground fault circuit interrupting function fails. The circuit interruption device for the ground fault has complex circuit and structure or high manufacturing difficulty and cost, and can realize the forced tripping function when the ground fault protection function fails, but after the forced tripping, the indicator lamp can still flash according to the original period and even is not lightened, so that the circuit interruption device can not play an effective warning role, the warning role of the circuit protection device is reduced, and potential safety hazards still exist.

Disclosure of Invention

The application is an extension of CN105896469B, and provides a circuit protection device for automatically monitoring operation faults. The disclosure of CN105896469B will be incorporated herein by reference. One technical problem to be solved by the present utility model is to provide a fault state holding circuit for the protective circuit interrupting device, which can hold fault state information when the ground fault protection function of the protective circuit interrupting device fails, so that the indicator lamp is lighted for a long time to indicate that the circuit protecting device has failed. Another technical problem to be solved by the present application is to provide a flicker warning circuit for the protective circuit interrupt device, so as to improve the warning effect.

In order to solve the technical problems, the technical scheme adopted by the application is as follows:

the circuit protection device for automatically monitoring operation faults comprises a ground fault protection unit and a self-fault monitoring unit, wherein the ground fault protection unit comprises a ground fault detection circuit, an alternating current power supply channel and an electromagnetic driving circuit, and the self-fault monitoring unit comprises an automatic test circuit, a measurement and control circuit and a warning circuit; the self-fault monitoring unit further comprises:

the fault state maintaining circuit comprises a zero clearing circuit and a fault state triggering circuit, wherein the zero clearing circuit receives a self fault monitoring signal U_TEST sent by the measurement and control circuit at regular time and sends a zero clearing signal U_clr; the fault state trigger circuit receives the clear signal U_clr and an emergency interrupt signal U_EI sent by the measurement and control circuit, and outputs and maintains fault state information U_err when the ground fault protection unit breaks down, so that the warning circuit maintains an alarm state to indicate that the circuit protection device breaks down.

Further, the zero clearing circuit includes a zero clearing capacitor, and the zero clearing capacitor captures level inversion information of the self-fault monitoring signal u_test and is used for generating the zero clearing signal u_clr.

Further, the fault state trigger circuit includes a voltage comparator, and the voltage comparator receives the clear signal u_clr and the emergency interrupt signal u_ei and outputs fault state information u_err.

Further, the fault state information U_err output by the fault state triggering circuit comprises a low level state and a high level state, the warning circuit receives the fault state information U_err, and in the self fault monitoring process, when the circuit protection device has no fault, the warning circuit stops warning; when the ground fault protection unit breaks down, the warning circuit keeps in a warning state.

The circuit protection device for automatically monitoring operation faults comprises a fault state trigger circuit, wherein the fault state trigger circuit outputs fault state information U_err, the fault state information U_err comprises low-level and high-level 2 states, and the warning circuit receives the fault state information U_err. In the self-fault monitoring process, when the circuit protection device has no fault, the indicator lamp of the warning circuit is extinguished; when the ground fault protection unit breaks down, the indicator lamp of the warning circuit flashes to emit light so as to improve the warning effect. The circuit is simple, economical and efficient.

Drawings

Fig. 1 is a structural frame diagram of an embodiment of the present application.

Fig. 2 is a schematic circuit diagram of an embodiment of the present application.

Fig. 3 is another schematic circuit diagram of an embodiment of the present application.

Detailed Description

The technical solutions of the present application are described in further detail below with reference to the accompanying drawings and examples, which are not to be construed as limiting the present application.

Fig. 1 is a structural frame diagram of a circuit protection device for automatically monitoring operation faults, and shows main functional units and control relations of the circuit protection device. The circuit protection device comprises a ground fault protection unit 1 and a self fault monitoring unit 2. The ground fault protection unit 1 realizes a ground fault protection function and outputs a fault state signal u_fs to the self-fault monitoring unit 2; the self-fault monitoring unit 2 outputs a ground fault current GFC to the ground fault protection unit 1, monitors a fault state signal u_fs of the ground fault protection unit 1, and outputs an emergency interrupt signal u_ei to the ground fault protection unit 1, thereby realizing self-fault monitoring and emergency protection functions.

As shown in fig. 1, the ground fault protection unit 1 includes a ground fault detection circuit 101, an ac power supply path 102, a manual test circuit 103, and an electromagnetic drive circuit 104. The ac power path 102 includes the magnetic switch 88, the ac power input terminals N1 and L1, and the load terminals N2 and L2. The magnetic switch 88 is used to switch on or off the electrical path between the ac power input terminal and the load terminal.

The ground fault detection circuit 101 includes a ground fault current sensor 150, a neutral repeat ground sensor 160, a ground fault detection chip 170, and a first direct current power supply 180. The ground fault current sensor 150 and the neutral repeat ground sensor 160 sense the ground fault current GFC occurring in the ac power supply path 102 and transmit a ground fault signal to the ground fault detection chip 170, and the ground fault detection chip 170 is configured to detect the ground fault signal transmitted from the ground fault current sensor 150 and the neutral repeat ground sensor 160 and output a ground fault interrupt signal u_gfi. The first dc power supply 180 is configured to provide the dc power supply V1 to the ground fault detection chip 170, and a negative electrode of the first dc power supply 180 is used as a logic ground GND of the circuit protection device.

The manual test circuit 103 outputs a ground fault current GFC to the ac power supply path 102 for testing the ground fault protection function of the ground fault protection unit 1.

The self-fault monitoring unit 2 comprises an automatic test circuit 201, a measurement and control circuit 202 and a warning circuit 203. The measurement and control circuit 202 periodically (e.g., once every 1 minute) sends out a self-fault monitoring signal u_test, starts a self-fault monitoring process, controls the automatic TEST circuit 201 to output a ground fault current GFC to the ground fault protection unit 1, monitors a fault state signal u_fs output by the electromagnetic driving circuit 104 in the ground fault protection unit 1, determines an operation condition of the ground fault protection unit 1, and outputs an emergency interrupt signal u_ei to the electromagnetic driving circuit 104 when the ground fault protection unit 1 fails, so as to trigger the electromagnetic driving circuit 104 to operate, and trip the magnetic switch 88 to implement an emergency protection function. Meanwhile, the self-fault monitoring signal u_test is connected to the warning circuit 203, and the warning circuit 203 sends out warning information. The warning circuit 203 may be a device such as an indicator lamp or a voice alarm, and an indicator lamp will be described as an example.

The measurement and control circuit 202 comprises an emergency protection circuit 280, a monitoring chip, an auxiliary circuit 260 and a second direct current power supply 270. The second dc power supply 270 provides the dc power V2 to the self-fault monitoring unit 2. The monitoring chip and the auxiliary circuit 260 send out a self-fault monitoring signal u_test at regular time, start the self-fault monitoring process, and terminate the self-fault monitoring process when receiving the fault status signal u_fs. The emergency protection circuit 280 sets a maximum operating time Tmax (e.g., 40 mS) for the self-fault monitoring process. In the self-fault monitoring process, the emergency protection circuit 280 receives the self-fault monitoring signal u_test, monitors the running time trunk of the self-fault monitoring process, and determines that the ground fault protection unit 1 is in a normal state when the trunk is smaller than the maximum running time Tmax; when the trunk is greater than the maximum operation time Tmax, the ground fault protection 1 is judged to be in a fault state, the emergency interrupt signal U_EI is output, the ground fault unit 1 is triggered to trip, and the emergency protection function is realized.

The self-failure monitoring unit 2 further includes a failure state holding circuit 204, and the failure state holding circuit 204 receives the self-failure monitoring signal u_test and the emergency interrupt signal u_ei and outputs failure state information u_err to the warning circuit 203.

The fault state retention circuit 204 includes a zero clearing circuit 210 and a fault state trigger circuit 290. The zero clearing circuit 210 includes a zero clearing capacitor 216, and the zero clearing circuit 210 captures level inversion information of the self-fault monitoring signal u_test at a starting instant of the self-fault monitoring process by means of the zero clearing capacitor 216, and outputs a zero clearing signal u_clr.

The fault state trigger circuit 290 includes a voltage comparator 294 that receives the clear signal u_clr and the emergency interrupt signal u_ei and outputs fault state information u_err. At the starting moment of the self-fault monitoring process, the fault state trigger circuit 290 is cleared by a clear signal U_clr, and fault state information U_err is output and maintained, so that the indicator light of the warning circuit 203 is turned off; when the ground fault protection unit 1 fails, on the one hand, the fault state trigger circuit 290 is set to 1 by an emergency interrupt signal u_ei, outputs and maintains fault state information u_err, so that the indicator light of the warning circuit 203 is kept in a lighting state to indicate that the circuit protection device 1 has failed; on the other hand, the fault state trigger circuit 290 is instantaneously cleared by the periodically occurring clear signal u_clr, so as to issue periodically varying fault state information u_err.

As can be seen from the above, the fault state holding circuit 204 outputs fault state information u_err, where the fault state information u_err includes 2 states of low level and high level, the warning circuit 203 receives the fault state information u_err, and when the circuit protection device has no fault in the self fault monitoring process, the indicator light of the warning circuit 203 is turned off; when the ground fault protection unit 1 fails, the indicator light of the warning circuit 203 blinks to illuminate, so as to improve the warning effect.

In a specific embodiment, as shown in fig. 2, a specific embodiment of the circuit protection device for automatically monitoring operation faults in the present application is shown, and a circuit embodiment of each functional unit of the circuit protection device shown in fig. 1 is shown.

In the ac power supply path 102, ac power is input from ac power input terminals L1 and N1, passes through a ground fault current GFC sensor 150 and a neutral line repetition ground sensor 160, and is then connected to the input terminal of the magnetic switch 88, and the output terminal of the magnetic switch 88 is connected to load terminals L2 and N2.

In the ground fault detection circuit 101, the ground fault current sensor 150, the neutral line repetition ground sensor 160, and the ground fault detection chip 170 sense the ground fault current GFC occurring in the ac power supply path 102, output a ground fault interrupt signal u_gfi, and when the ground fault current GFC exceeds the trip threshold value, the ground fault interrupt signal u_gfi changes from low level to high level; when the ground fault current GFC is less than the trip threshold, the ground fault interrupt signal u_gfi remains low.

In the ground fault detection circuit 101, the first dc power supply 180 is a bridge rectifier circuit, whose output positive electrode is connected to V1 and whose output negative electrode is connected to the logic ground GND of the circuit protection device.

The electromagnetic driving circuit 104 comprises a tripping coil 142 and a silicon controlled rectifier SCR, wherein the anode of the silicon controlled rectifier SCR outputs a fault state signal U_FS, and the U_FS is respectively connected with the tripping coil 142 and a monitoring chip and auxiliary circuit 260; the cathode of the SCR is grounded to the logic ground GND, and a ground fault interrupt signal U_GFI is connected with the control electrode of the SCR through a resistor 149, and an emergency interrupt signal U_EI is connected with the control electrode of the SCR through a diode 148. When the ground fault interrupt signal u_gfi and/or the emergency interrupt signal u_ei are at a high level, the thyristors SCR are turned on, causing the fault status signal u_fs to be at a low level. When a ground fault occurs, the SCR of the electromagnetic driving circuit 104 is in a conductive state, so that the trip coil 142 and the magnetic switch 88 perform a trip action, and the ac power supply to the load and the socket terminal is cut off, thereby realizing a ground fault protection function.

In the monitor chip and the auxiliary circuit 260, the monitor chip 263 periodically changes the level of the self-fault-monitoring signal u_test from low to high, starts the self-fault-monitoring process, and receives the fault-state signal u_fs sent from the electromagnetic driving circuit 104, and when the fault-state signal u_fs changes from high to low, immediately changes the level of the self-fault-monitoring signal u_test from high to low, and ends the self-fault-monitoring process. On the other hand, the self-fault detection signal u_test is connected to the warning circuit 203 at the same time, and during the self-fault detection process, when the SCR is functioning normally, the level of the fault status signal u_fs will be turned once no matter whether the ground fault protection unit 1 has a fault or not, and the indicator lamp of the warning circuit 203 will be turned on once in a non-distinguishing and short-term manner.

In the emergency protection circuit 280, the input resistor 281, the delay capacitor 282 and the reference voltage Ud set a maximum operating time Tmax for the self-fault monitoring process. In the self-fault monitoring process, the self-fault monitoring signal u_test is kept at a high level, the self-fault monitoring signal u_test charges the delay capacitor 282 through the resistor 281, when the ground fault protection unit 1 fails, the running time trunk of the self-fault monitoring process is greater than the maximum running time Tmax, the voltage on the delay capacitor 282 is higher than Ud, and the emergency interrupt signal u_ei is changed from a low level to a high level; when the circuit protection device is not faulty, trunk is smaller than Tmax, the voltage of the delay capacitor 282 is lower than Ud, and the emergency interrupt signal u_ei is kept low.

In the clear circuit 210, the self-fault detection signal u_test is connected to one electrode of the clear capacitor 216 through the resistor 215, the other electrode of the clear capacitor 216 is connected to the base of the transistor 217 and one electrode of the resistor 218 at the same time, and the other electrode of the resistor 218 is connected to the logic ground GND. The emitter of the transistor 217 is connected to the logic ground GND, and the collector of the transistor 217 outputs a clear signal u_clr. The clear circuit 210 uses the charge-discharge characteristic of the clear capacitor 216 and the isolation characteristic of the dc voltage to obtain transient information of the self-fault monitoring signal u_test, and the process is as follows: when the self-fault monitoring signal u_test is changed from low level to high level, the potential difference at two ends of the clear capacitor 216 will not suddenly change, the self-fault monitoring signal u_test injects current into the base electrode of the triode 217 through the resistor 215, so that the triode 217 is turned on, the clear signal u_clr connected to the collector electrode of the triode 217 is changed from high level to low level, then the potential difference at two ends of the clear capacitor 216 is gradually increased, the current flowing through the clear capacitor 216 is gradually reduced until the triode 217 is turned off, and the level of the u_clr is maintained by the fault state trigger circuit 290; when the self-fault monitoring signal u_test is changed from high level to low level, the charge in the clear capacitor 216 is gradually released through the resistor 215 and the resistor 218 until the potential difference across the clear capacitor 216 is zero, during which the base of the triode 217 is kept low level, the triode 217 is kept in an off state, and the state of u_clr is unchanged. The output u_clr of the zero clearing circuit 210 only appears when the self-fault detection signal u_test changes from low to high, so as to obtain transient information of the skip-pass on the level of the self-fault detection signal u_test.

In the fault state trigger circuit 290, a positive feedback circuit is formed by a voltage comparator 294 and a positive feedback resistor 293, the voltage comparator 294 outputs fault state information u_err, the negative input end of the voltage comparator 294 is connected with a reference voltage Ub, a clear signal u_clr is connected with the positive input end Ua of the voltage comparator 294, an emergency interrupt signal u_ei is connected with the positive input end Ua of the voltage comparator 294 through a diode 291 and a resistor 292, one electrode of the resistor 293 is connected with the positive input end Ua of the voltage comparator 294, the other electrode of the resistor 293 is connected with the output u_err of the voltage comparator 294, and the u_err is connected to the warning circuit 203. Thus, the voltage comparator 294 and the peripheral elements implement a bistable (high and low) output function, which is the process of: in the initial state, the emergency interrupt signal u_ei is low, the clear signal u_clr is high, when the clear signal u_clr is changed from high to low, the positive input voltage Ua of the voltage comparator 294 is lower than the negative input voltage Ub (e.g., ua is about 0.3V and Ub is about 3V), the fault state information u_err is low (e.g., 0.3V), and due to the positive feedback effect of the resistor 293, the positive input voltage Ua of the voltage comparator 294 is kept lower than the negative input voltage Ub (Ua is about 0.3V and Ub is about 3V) when the transistor 217 in the clear circuit 210 is turned off; when the emergency interrupt signal u_ei is at a high level (e.g., 11V), the positive input voltage Ua of the voltage comparator 294 is higher than the negative input voltage Ub thereof (e.g., if Ua is set to 6.5V, ua > Ub) in the case of the transistor 217 being turned off, the fault state signal u_err is inverted from a low level to a high level (e.g., if u_err is set to 11V), at which time the Ua is approximately equal to u_err, and thereafter, due to the positive feedback effect of the resistor 293 as well, and due to the unidirectional conduction characteristic of the diode 291, the Ua remains unchanged (approximately equal to u_err) when the emergency interrupt signal u_ei is inverted from the high level to the low level, so that the condition of Ua > Ub is maintained, and the output u_err of the voltage comparator 294 remains in the high state.

In another embodiment, as shown in FIG. 3, another embodiment of a fault state holding circuit 204 is presented. The fault state retention circuit 204 in fig. 3 is capable of performing the same signaling function as the fault state retention circuit 204 in fig. 2 to perform the fault state retention function described in fig. 1.

In the clearing circuit 210, one electrode of the resistor 215 is connected to the ground fault monitoring signal u_test, the other electrode of the resistor 215 is connected to one electrode of the clearing capacitor 216, the other electrode of the clearing capacitor 216 is simultaneously connected to one electrode of the resistor 218 and the base of the transistor 217, the other electrode of the resistor 218 is connected to the logic ground GND, the collector of the transistor 217 is connected to the second dc power supply 270 (V2), and the emitter of the transistor 217 outputs the clearing signal u_clr. The clear circuit 210 operates on the principle that: when the self-fault monitoring signal u_test is at a low level, the resistor 215, the zero clearing capacitor 216 and the resistor 218 form a discharging loop, so that the potential difference at two ends of the zero clearing capacitor 216 is zero, the voltage of the base electrode of the triode 217 is 0V, the triode 217 is turned off, and the voltage of u_clr is ub_l (e.g., set to 3V); when the u_test rises from low level to high level, initially, the u_test injects current into the base of the transistor 217 through the resistor 215 and the clear capacitor 216, so that the transistor 217 is turned on instantaneously, the output u_clr of the transistor 217 rises instantaneously to ub_h (e.g., set to 10V), and thereafter, during the period when the u_test is kept high level, as the potential difference across the clear capacitor 216 increases gradually through charging, the voltage at the base of the transistor 217 decreases gradually to 0V, the transistor 217 turns off, and the u_clr voltage returns gradually to ub_l; when u_test falls from high to low, the clear capacitor 216 is discharged, the transistor 217 remains in the off state, and the u_clr state remains unchanged. Therefore, the zero clearing information u_clr output by the zero clearing circuit 210 generates a transient level flip (from ub_l to ub_h, and back to ub_l) only at the instant when the u_test jumps from low level to high level in the round trip transition process between high level and low level of the u_test, thereby realizing the capturing function of the transient information of the rising edge of the u_test level.

In the fault state holding circuit 290, a positive feedback circuit is formed by a voltage comparator 294 and a positive feedback resistor 293, the voltage comparator outputs a fault state signal u_err, wherein an anode of a diode 291 is connected to the u_ei, a cathode of the diode 291 is connected to one electrode of a resistor 292, the other electrode of the resistor 292 is connected to the resistor 295, the positive feedback resistor 293 and a positive input Ua of the voltage comparator 294 at the same time, the other electrode of the resistor 295 is connected to a logic ground GND, the other electrode of the positive feedback resistor 293 is connected to an output u_err of the voltage comparator 294, a negative input Ub of the voltage comparator 294 is connected to a voltage divider circuit formed by a second dc power supply V2, the resistor 297 and the resistor 296, and the negative input Ub of the voltage comparator 294 is connected to a clear signal u_clr at the same time.

The operating principle of the fault state trigger circuit 290 is: in the initial state, the level of the clear signal u_clr (i.e., ub) is ub_l (e.g., set to 3V), the emergency interrupt signal u_ei is low (about 0.3V), the fault state signal u_err is low (about 0.3V), at this time, the positive input voltage Ua of the voltage comparator 294 is ua_1 (lower than 0.3V), the negative input voltage Ub of the voltage comparator 294 is ub_l, ua_1< ub_l, and the fault state signal u_err is kept low; at this time, when the clear signal u_clr is changed from the low level ub_l to the high level ub_h (e.g., 10V) and from the high level ub_h to the low level ub_l, ub is always greater than Ua, and the fault state signal u_err remains at the low level; when the emergency interrupt signal u_ei changes from low level to high level (e.g., 11V), the positive input voltage Ua of the voltage comparator 294 rises from ua_1 to ua_2 (determined by the resistor 292, the resistor 295 and the positive feedback resistor 293, e.g., set to 4.5V), the negative input voltage Ub thereof is ub_l, ua > Ub, the fault state signal u_err changes from low level to high level (e.g., 11V), at this time, under the action of the positive feedback resistor 293, ua rises from ua_2 to ua_3 (determined by the resistor 292, the positive feedback resistor 293 and the resistor 295, e.g., set to 6.5V), after which, if the emergency interrupt signal u_ei changes from high level to low level, the positive input voltage Ua of the voltage comparator 294 falls back to ua_4 (determined by the resistor 295 and the positive feedback resistor 293, e.g., 3.3V) due to unidirectional conduction of the diode 291, ua_4 is greater than ub_l, and thus the fault state signal u_err remains high, thereby maintaining the fault state information; when the clear signal u_clr rises from the low level ub_l to the high level ub_h in the case where the fault state signal u_err is at the high level, the negative input voltage Ub of the voltage comparator 294 rises from the low level ub_l to the high level ub_h, ub_h > ua_3, i.e., the negative input voltage Ub of the voltage comparator 294 is greater than the positive input voltage Ua thereof, and the fault state signal u_err instantaneously returns to the low level.

In the two embodiments of fig. 2 and 3, in each self-fault monitoring process, the warning circuit 203 receives the fault state information u_err, when the ground fault protection circuit 1 fails, the level of the fault state information u_err is changed from high level to low level and is turned to high level, so that the indicator light of the warning circuit 203 flashes once, thereby eliminating the defect of no distinction and short flashing generated by the self-fault monitoring signal u_test output by the monitoring chip and the auxiliary circuit 260 only, and improving the warning effect. In this embodiment, the zero clearing circuit 210 and the fault state triggering circuit 290 are simple, economical and practical, and can effectively implement the fault state maintaining function.

It is to be understood by one of ordinary skill in the art that the drawings and embodiments herein are merely illustrative of the function, structure and principles of the present application and should not be taken as limiting the understanding of the present application; at the same time, the objects of the present application have been achieved. The above embodiments may be modified without departing from the principles of the present application, and the scope of the present application is therefore defined by the claims.

Claims (4)

1. A circuit protection device for automatically monitoring operation faults, the circuit protection device comprises a ground fault protection unit (1) and a self-fault monitoring unit (2), the ground fault protection unit (1) comprises a ground fault detection circuit (101), an alternating current power supply channel (102) and an electromagnetic driving circuit (104), and the self-fault monitoring unit (2) comprises an automatic test circuit (201), a measurement and control circuit (202) and a warning circuit (203); characterized in that the self-fault monitoring unit (2) further comprises:

the fault state maintaining circuit (204), the fault state maintaining circuit (204) comprises a zero clearing circuit (210) and a fault state triggering circuit (290), wherein the zero clearing circuit (210) receives a self fault monitoring signal U_TEST sent out by the measurement and control circuit (202) at regular time and sends out a zero clearing signal U_clr; the fault state trigger circuit (290) receives the clear signal U_clr and an emergency interrupt signal U_EI sent by the measurement and control circuit (202), and outputs and maintains fault state information U_err when the ground fault protection unit (1) breaks down, so that the warning circuit (203) maintains an alarm state to show that the circuit protection device breaks down.

2. The circuit protection device for automatically monitoring an operation fault according to claim 1, wherein the clear circuit (210) comprises a clear capacitor (216), the clear capacitor (216) capturing level inversion information of the self-fault detection signal u_test for generating the clear signal u_clr.

3. The circuit protection device for automatically monitoring an operation fault according to claim 1, wherein the fault state trigger circuit (290) comprises a voltage comparator (294), and the voltage comparator (294) receives the clear signal u_clr and the emergency interrupt signal u_ei and outputs fault state information u_err.

4. A circuit protection device for automatically monitoring an operation failure according to claim 3, wherein the failure state information u_err outputted from the failure state trigger circuit (290) includes two states of a low level and a high level, the warning circuit (203) receives the failure state information u_err, and the warning circuit (203) stops warning when the circuit protection device has no failure during the self-failure monitoring; when the ground fault protection unit (1) fails, the warning circuit (203) maintains a warning state.

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