Self-locking circuit for current detection

Abstract

A self-locking circuit for current detection comprises a power input end, a current detection branch, a self-locking operation branch and a load alarm branch. The power supply input end is used for supplying power to the self-locking operation branch circuit and the load alarm branch circuit; the current detection branch is used for detecting the state of a load working current and outputting a current state signal; the self-locking operation branch is used for receiving the current state signal and judging whether self-locking operation is carried out or not and sending out an operation signal; the load alarm branch is used for receiving the operation signal and carrying out normal operation or power-off alarm operation on the load; the current detection branch circuit, the self-locking operation branch circuit and the load alarm branch circuit are connected in sequence, and the power supply input end is connected with the self-locking operation branch circuit and the load alarm branch circuit; according to the utility model, through the self-locking circuit for current detection, the electronic equipment can automatically enter a self-locking mechanism for cutting off a power supply and giving an alarm to be continuously protected when overcurrent occurs.

Description

Technical Field

[0001] The utility model relates to the field of electronic equipment circuit protection, in particular to a self-locking circuit for current detection. Background Art

[0002] Whether it is household electronic equipment or industrial electronic equipment, most of them are equipped with real-time overcurrent detection protection circuits. Generally, the operating current of the electronic equipment is monitored in real time through a current detection module. When the operating current overcurrent occurs, the current detection module generates a corresponding voltage signal, briefly cuts off the power supply to the original circuit and issues an alarm, thereby guiding maintenance personnel to inspect and repair the electronic equipment; however, once an electronic device has an overcurrent phenomenon, this phenomenon will not recover on its own, and this state cannot be restored on its own. Once the maintenance personnel are not on site and cannot provide timely inspection and maintenance services for the electronic equipment, the electronic equipment will very likely spontaneously combust, thereby causing a safety accident; therefore, how to ensure that the electronic equipment continues to be protected for a long time after the overcurrent phenomenon is detected is particularly important in the self-locking mechanism of disconnecting the power supply and issuing an alarm. Utility Model Content

[0003] In response to the problems raised in the background technology, the purpose of the present invention is to provide a self-locking circuit for current detection to solve the problem that electronic equipment cannot be continuously protected for a long time after detecting overcurrent.

[0004] To achieve this purpose, the present invention adopts the following technical solutions:

[0005] A current detection self-locking circuit includes a power input terminal Power, a current detection branch, a self-locking operation branch and a load alarm branch;

[0006] The power input terminal Power is used to supply power to the self-locking operation branch and the load alarm branch; the current detection branch is used to detect the state of the load Load working current and output the current state signal State; the self-locking operation branch is used to receive the current state signal State and determine whether to perform the self-locking operation and issue the operation signal Action; the load alarm branch is used to receive the operation signal Action and perform normal operation or power-off alarm operation on the load Load;

[0007] The current detection branch, the self-locking operation branch, and the load alarm branch are connected in sequence, and the power input terminal Power is connected to the self-locking operation branch and the load alarm branch respectively.

[0008] Preferably, the voltage of the current state signal State is 12V or 0V, and the voltage of the power input terminal Power is 12V.

[0009] Preferably, the current state signal State includes a current state normal signal and a current state abnormal signal, the current state normal signal State is an analog voltage of 0V, and the current state abnormal signal State is an analog voltage of 12V;

[0010] The current detection branch includes a current detection module, a diode D3 and a resistor R4;

[0011] The anode of the diode D3 is connected to the current detection module, the cathode of the diode D3 is connected to the self-locking operation branch, and is grounded through the resistor R4.

[0012] Preferably, the current detection module is a current transformer, the diode D3 is 1N4148, and the resistance of the resistor R4 is 10K.

[0013] Preferably, the self-locking operation branch includes a maintaining module, a self-locking module and an operating module;

[0014] One end of the maintaining module is connected to the cathode of the diode D3 and one end of the resistor R4 respectively, and the other end of the maintaining module is connected to one end of the self-locking module and one end of the operating module respectively;

[0015] The other end of the operating module is respectively connected to the power input terminal Power, the other end of the self-locking module and the load alarm branch.

[0016] Preferably, the operation signal Action includes a normal working signal and a power-off alarm signal, the normal working signal is a constant voltage of 0V, and the power-off alarm signal is a constant voltage of 12V;

[0017] The maintenance module includes a resistor R1 and a capacitor C1;

[0018] The self-locking module includes a resistor R2, a resistor R6, a resistor R7, a diode D1, a transistor Q1 and a transistor Q5;

[0019] The operating module includes a resistor R3, a resistor R5, a transistor Q2 and a transistor Q3;

[0020] One end of the resistor R1 is connected to the cathode of the diode D3 and one end of the resistor R4, and the other end of the resistor R1 is connected to the cathode of the diode D1, and is simultaneously connected to the base of the transistor Q5 through the resistor R6, is connected to the base of the transistor Q2 through the resistor R5, and is grounded through the capacitor C1;

[0021] The emitter of the transistor Q5 is grounded, the collector of the transistor Q5 is connected to the base of the transistor Q1 through the resistor R2, and is respectively connected to the emitter of the transistor Q1, the power input terminal Power, and the load alarm branch through the resistor R7, and the collector of the transistor Q1 is connected to the anode of the diode D1;

[0022] The emitter of the transistor Q2 is grounded, the collector is connected to the base of the transistor Q3, and is respectively connected to the power input terminal Power and the load alarm branch through the resistor R3. The collector of the transistor Q3 is connected to the load alarm branch, and the emitter of the transistor Q3 is grounded.

[0023] Preferably, the resistance of the resistor R1 is 510K, and the capacitor C1 is an aluminum capacitor with a capacitance of 100uF;

[0024] The resistance of the resistor R2 is 10K, the resistance of the resistor R6 is 10K, the resistance of the resistor R7 is 100K, the model of the diode D1 is 1N4148, the model of the transistor Q1 is 9012, and the model of the transistor Q5 is 9013;

[0025] The resistance of the resistor R3 is 3K, the resistance of the resistor R5 is 3K, the model of the transistor Q2 is 9013, and the model of the transistor Q3 is 9013.

[0026] Preferably, the load alarm branch includes a load module and an alarm module;

[0027] One end of the load module is connected to the power input terminal Power, the self-locking module and the operating module respectively, and the other end is connected to the operating module and the alarm module respectively.

[0028] Preferably, the load module includes a diode D2, a relay K1 and a load, and the relay K1 is provided with an input path and an output path;

[0029] The alarm module includes a relay K2, a speaker LS1 and a warning light DS1, and the relay K2 is provided with an input path and an output path;

[0030] The cathode of the diode D2 is connected to the power input terminal Power, one end of the resistor R3, one end of the resistor R7, and the emitter of the transistor Q1, respectively; the anode of the diode D2 is connected to the collector of the transistor Q3; the input path of the relay K1 and the input path of the relay K2 are both connected in parallel with the diode D2;

[0031] One end of the output path of the relay K1 is connected to the power input terminal Power, and the other end of the output path of the relay K1 is connected to the load Load; one end of the output path of the relay K2 is connected to the power input terminal Power, and the other end of the output path of the relay K2 is grounded through the speaker LS1 and the warning light DS1 respectively.

[0032] Preferably, the diode D2 is of model 1N4007, the relay K1 is a single-channel DC relay, and the relay K2 is a dual-channel DC relay.

[0033] Compared with the prior art, one of the above technical solutions has the following beneficial effects:

[0034] The utility model realizes overcurrent detection of the load of the electronic device through the current detection branch; at the same time, the self-locking operation circuit receives the current state signal sent from the current detection branch and controls the load alarm branch, thereby realizing the function of continuously protecting the electronic device by automatically entering the self-locking mechanism of disconnecting the power supply and issuing an alarm after the electronic device detects an overcurrent. BRIEF DESCRIPTION OF THE DRAWINGS

[0035] Figure 1 This is a branch circuit structure diagram of an embodiment of the present utility model;

[0036] Figure 2 This is a circuit diagram of an embodiment of the present utility model;

[0037] Figure 3 This is a circuit diagram of an embodiment of the present utility model;

[0038] Among them: current detection branch 1, current detection module 11, self-locking operation branch 2, maintenance module 21, self-locking module 22, operation module 23, load alarm branch 3, load module 31, alarm module 32, power input terminal Power, current state signal State and operation signal Action. DETAILED DESCRIPTION

[0039] The following describes embodiments of the present invention in detail. Examples of the embodiments are shown in the accompanying drawings, wherein the same or similar reference numerals throughout represent the same or similar elements or elements having the same or similar functions. The embodiments described below with reference to the accompanying drawings are exemplary and are intended only to explain the present invention and are not to be construed as limiting the present invention.

[0040] In the description of the present invention, it should be understood that the terms "upper", "lower", "front", "back", "left", "right", "top", "bottom", "inside", "outside", etc., indicating directions or positional relationships, are based on the directions or positional relationships shown in the accompanying drawings. They are only for the convenience of describing the present invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific direction, be constructed and operated in a specific direction. Therefore, they cannot be understood as limitations on the present invention.

[0041] Furthermore, the terms "first," "second," and "third" are used for descriptive purposes only and should not be understood to indicate or imply relative importance or to implicitly specify the quantity of the technical features being referred to. Thus, a feature identified as "first," "second," and "third" may explicitly or implicitly include one or more of the features.

[0042] It should be noted that, unless otherwise expressly specified or limited, the terms "mounted," "connected," and "connected" should be understood broadly. For example, they may refer to fixed, detachable, or integral connections; mechanical or electrical connections; direct or indirect connections through an intermediary; and internal communication between two components. Those skilled in the art will understand the specific meanings of these terms in the present invention based on the specific circumstances.

[0043] The following is combined with Figures 1 to 3 The technical solution of the self-locking circuit for current detection of the present invention is further explained through specific implementation methods.

[0044] A current detection self-locking circuit includes a power input terminal Power, a current detection branch 1, a self-locking operation branch 2 and a load alarm branch 3;

[0045] The power input terminal Power is used to supply power to the self-locking operation branch 2 and the load alarm branch 3; the current detection branch 1 is used to detect the state of the load Load working current and output the current state signal State; the self-locking operation branch 2 is used to receive the current state signal State and determine whether to perform the self-locking operation and issue the operation signal Action; the load alarm branch 3 is used to receive the operation signal Action and perform normal operation or power-off alarm operation on the load Load;

[0046] The current detection branch 1, the self-locking operation branch 2 and the load alarm branch 3 are connected in sequence, and the power input terminal Power is connected to the self-locking operation branch 2 and the load alarm branch 3 respectively.

[0047] Specifically, if Figures 1 to 2As shown, when the current detection branch 1 detects that the working current of the load Load is normal, the current state signal State will maintain the self-locking state of the self-locking operation branch 2, and the operation signal Action will also maintain the normal operation state of the load Load of the load alarm branch 3; when the current detection branch 1 detects that the working current of the load Load is abnormal, the current state signal State will activate the self-locking operation of the self-locking branch 2, and the operation signal Action will also activate the power-off alarm operation of the load Load of the load alarm branch 3;

[0048] Once the self-locking operation branch 2 starts the self-locking operation, even if the detection result of the current detection branch 1 on the load Load working current changes from abnormal to normal, the self-locking state of the self-locking operation branch 2 and the power-off alarm state of the load alarm branch 3 cannot be released; in order to release the self-locking and power-off alarm states, the power input terminal Power must be powered off, and the power-off time must exceed one second.

[0049] Particularly, the voltage of the current state signal State is 12V or 0V, and the voltage of the power input terminal Power is 12V.

[0050] Since the voltage of the current state signal State is 12V or 0V, in order to match it, the voltage of the power input terminal Power is also set to 12V.

[0051] Furthermore, the current state signal State includes a current state normal signal and a current state abnormal signal, the current state normal signal State is an analog voltage of 0V, and the current state abnormal signal State is an analog voltage of 12V;

[0052] The current detection branch 1 includes a current detection module 11, a diode D3 and a resistor R4;

[0053] The anode of the diode D3 is connected to the current detection module 11 , and the cathode of the diode D3 is connected to the self-locking operation branch 2 and is grounded through the resistor R4 .

[0054] like Figure 3 As shown, when the current detection module 11 detects the working current of the load Load normally, the current detection module 11 will output a current state normal signal with an analog voltage of 0V; when the current detection module 11 detects the working current of the load Load abnormally, the current detection module 11 will output a current state abnormal signal with an analog voltage of 12V;

[0055] The diode D3 plays the role of unidirectional conduction and reverse blocking, and is used to protect the current detection module 11;

[0056] The resistor R4 is pulled down to ground to prevent the voltage of the current state signal State from floating.

[0057] Furthermore, the current detection module 11 is a current transformer, the diode D3 is 1N4148, and the resistance of the resistor R4 is 10K.

[0058] For the current detection module 11, the current transformer can convert the detected current into an analog voltage for output through isolation detection. This method has a simple structure and the detection result is very accurate.

[0059] As for the diode D3, the 1N4148 selected for the diode D3 is a small circuit for unidirectional conduction isolation with a high signal frequency, which is compatible with the analog voltage detected by the current transformer;

[0060] For the resistor R4, 10K is a common choice of pull-down resistor value.

[0061] The self-locking operation branch 2 includes a maintaining module 21, a self-locking module 22 and an operating module 23;

[0062] One end of the maintaining module 21 is connected to the cathode of the diode D3 and one end of the resistor R4, respectively. The other end of the maintaining module 21 is connected to one end of the self-locking module 22 and one end of the operating module 23, respectively.

[0063] The other end of the operating module (23) is respectively connected to the power input terminal Power, the other end of the self-locking module 22 and the load alarm branch 3.

[0064] like Figure 3 As shown, when the maintaining module 21, the self-locking module 22 and the operating module 23 receive the normal current state signal, the self-locking module 22 and the operating module 23 will maintain the normal working state of the load, and the maintaining module 21 will not be activated; when the maintaining module 21, the self-locking module 22 and the operating module 23 receive the abnormal current state signal, the self-locking module 22 will be adjusted to the self-locking state, and the operating module 23 will be adjusted to the power-off alarm state, and the function of the maintaining module 21 is to maintain the above two states.

[0065] In particular, the operation signal Action includes a normal working signal and a power-off alarm signal, the normal working signal is a constant voltage of 0V, and the power-off alarm signal is a constant voltage of 12V;

[0066] The maintenance module 21 includes a resistor R1 and a capacitor C1;

[0067] The self-locking module 22 includes a resistor R2, a resistor R6, a resistor R7, a diode D1, a transistor Q1 and a transistor Q5;

[0068] The operating module 23 includes a resistor R3, a resistor R5, a transistor Q2 and a transistor Q3;

[0069] One end of the resistor R1 is connected to the cathode of the diode D3 and one end of the resistor R4, and the other end of the resistor R1 is connected to the cathode of the diode D1, and is simultaneously connected to the base of the transistor Q5 through the resistor R6, is connected to the base of the transistor Q2 through the resistor R5, and is grounded through the capacitor C1;

[0070] The emitter of the transistor Q5 is grounded, the collector of the transistor Q5 is connected to the base of the transistor Q1 through the resistor R2, and is respectively connected to the emitter of the transistor Q1, the power input terminal Power, and the load alarm branch 3 through the resistor R7, and the collector of the transistor Q1 is connected to the anode of the diode D1;

[0071] The emitter of the transistor Q2 is grounded, the collector is connected to the base of the transistor Q3, and is respectively connected to the power input terminal Power and the load alarm branch 3 through the resistor R3. The collector of the transistor Q3 is connected to the load alarm branch 3, and the emitter of the transistor Q3 is grounded.

[0072] When the self-locking module 22 and the operating module 23 receive the normal current state signal, the normal current state signal cannot charge the capacitor C1 through the diode D3 and the resistor R1. No voltage exists at the positive electrode of the capacitor C1, the transistor Q2 is turned off, and the transistor Q3 is turned on. The collector of the transistor Q3 will emit the normal working signal with a constant voltage of 0V, and the power input terminal Power will supply power to the load alarm branch 3. At the same time, the transistor Q5 is turned off, and the transistor Q1 is turned off. The power input terminal Power cannot supply power to the capacitor C1 through the diode D1, and thus the self-locking continuity cannot be formed.

[0073] When the self-locking module 22 and the operating module 23 receive the abnormal current state signal, the abnormal current state signal charges the capacitor C1 through the diode D3 and the resistor R1. When the voltage on the capacitor C1 reaches a level sufficient to turn on the transistor Q2, the transistor Q2 is turned on and the transistor Q3 is turned off. The collector of the transistor Q3 will emit the power-off alarm signal with a constant voltage of 12V, and the power input terminal Power will be unable to supply power to the load alarm branch 3, thereby realizing the power-off operation. At the same time, when the power When the voltage on capacitor C1 reaches a level sufficient to turn on transistor Q5, transistor Q5 is turned on, transistor Q1 is turned on, and the power input terminal Power can charge capacitor C1 through diode D1, thereby entering a closed-loop self-locking state. Once the closed-loop and power-off state is entered, a certain amount of electricity must remain on capacitor C1, and the closed-loop self-locking state will continuously charge capacitor C1. Therefore, to break this state, the power must be turned off and then on again, and the power-off time must exceed the time it takes for capacitor C1 to discharge, which lasts about one second.

[0074] Furthermore, the resistance of the resistor R1 is 510K, and the capacitor C1 is an aluminum capacitor with a capacitance of 100uF;

[0075] The resistance of the resistor R2 is 10K, the resistance of the resistor R6 is 10K, the resistance of the resistor R7 is 100K, the model of the diode D1 is 1N4148, the model of the transistor Q1 is 9012, and the model of the transistor Q5 is 9013;

[0076] The resistance of the resistor R3 is 3K, the resistance of the resistor R5 is 3K, the model of the transistor Q2 is 9013, and the model of the transistor Q3 is 9013.

[0077] For the maintenance module 21, the resistor R1 and the capacitor C1 are combined into a proportional link for debouncing against external interference;

[0078] For the self-locking module 22, the values ​​of the resistors R2, R6, and R7 are selected so that both the transistor Q5 and the transistor Q1 operate in the saturation region, so that the transistors Q5 and Q1 are used only as switches; the low-side transistor Q5 uses a 9013 NPN transistor and the high-side transistor Q1 uses a 9012 PNP transistor, which is a relatively conventional self-locking circuit structure;

[0079] For the operating module 22, the values ​​of the resistors R3 and R5 are selected so that the transistors Q2 and Q3 both operate in the saturation region, so that the transistors Q2 and Q3 are only used as switches; the transistors Q2 and Q3 are both NPN transistors of model 9013, and the stacking effect of the two NPN transistors can realize the on-off control of the load alarm branch 3.

[0080] The load alarm branch 3 includes a load module 31 and an alarm module 32;

[0081] One end of the load module 31 is connected to the power input terminal Power, the self-locking module 22 and the operating module 23 respectively, and the other end is connected to the operating module 23 and the alarm module 32 respectively.

[0082] like Figure 2 As shown, when the transistor Q3 is turned on, the collector of the transistor Q3 will send out the normal working signal with a constant voltage of 0V, and the power input terminal Power will only supply power to the load module 31. The load module 31 will start, and the alarm module 32 will not start; when the transistor Q3 is turned off, the collector of the transistor Q3 will send out the power-off alarm signal with a constant voltage of 12V, and the power input terminal Power will only supply power to the alarm module 32. The load module 31 will not start, but the alarm module 32 will start.

[0083] In particular, the load module 31 includes a diode D2, a relay K1 and a load, wherein the relay K1 is provided with an input path and an output path;

[0084] The alarm module 32 includes a relay K2, a speaker LS1 and a warning light DS1. The relay K2 is provided with an input path and an output path;

[0085] The cathode of the diode D2 is connected to the power input terminal Power, one end of the resistor R3, one end of the resistor R7, and the emitter of the transistor Q1, respectively; the anode of the diode D2 is connected to the collector of the transistor Q3; the input path of the relay K1 and the input path of the relay K2 are both connected in parallel with the diode D2;

[0086] One end of the output path of the relay K1 is connected to the power input terminal Power, and the other end of the output path of the relay K1 is connected to the load Load; one end of the output path of the relay K2 is connected to the power input terminal Power, and the other end of the output path of the relay K2 is grounded through the speaker LS1 and the warning light DS1 respectively.

[0087] When the transistor Q3 is turned on, the input path of the relay K1 is turned on, the output path of the relay K1 is closed and turned on, the power input terminal Power will supply power to the load Load through the output path of the relay K1, and the input path of the relay K2 is also turned on, the output path of the relay K2 is also closed and turned on, the power input terminal Power is open, and cannot supply power to the speaker LS1 and the warning light DS1. This is the working state when the working current of the load Load is normal;

[0088] When the transistor Q3 is turned off, the input path of the relay K1 is cut off, the output path of the relay K1 is cut off, and the power input terminal Power cannot supply power to the load Load through the output path of the relay K1, thereby realizing a power-off operation; and the input path of the relay K2 is cut off, the output path of the relay K2 is also cut off, and the power input terminal Power supplies power to the speaker LS1 and the warning light DS1, thereby realizing an alarm operation.

[0089] Furthermore, the diode D2 is of model 1N4007, the relay K1 is a single-channel DC relay, and the relay K2 is a dual-channel DC relay.

[0090] For the load module 31, since the voltage type of the power input terminal Power is DC with a voltage value of 12V, and only a single circuit can be used to control the power on and off of the load Load, the relay K1 needs to be a single-channel DC relay;

[0091] For the alarm module 32, since the voltage type of the power input terminal Power is DC with a voltage value of 12V, and since the power to drive the speaker LS1 and the warning light DS1 is relatively large, two channels are required to control the on and off of the speaker LS1 and the warning light DS1. Therefore, the relay K2 needs to be a dual-channel DC relay.

[0092] For the load module 31 and the alarm module 32 , the diode D2 is 1N4007, which is a common choice for the relay freewheeling function.

[0093] The technical principles of the present invention have been described above with reference to specific embodiments. These descriptions are intended solely to illustrate the principles of the present invention and should not be construed in any way as limiting the scope of protection of the present invention. Based on the explanations herein, those skilled in the art will be able to devise other specific implementations of the present invention without inventive effort, and such implementations will fall within the scope of protection of the present invention.

Claims

1. A self-locking circuit for current detection, characterized in that: It includes a power input terminal Power, a current detection branch (1), a self-locking operation branch (2) and a load alarm branch (3); The power input terminal Power is used to supply power to the self-locking operation branch (2) and the load alarm branch (3); the current detection branch (1) is used to detect the state of the load Load working current and output the current state signal State; the self-locking operation branch (2) is used to receive the current state signal State and determine whether to perform a self-locking operation and issue an operation signal Action; the load alarm branch (3) is used to receive the operation signal Action and perform normal operation or power-off alarm operation on the load Load; The current detection branch (1), the self-locking operation branch (2) and the load alarm branch (3) are connected in sequence, and the power input terminal Power is connected to the self-locking operation branch (2) and the load alarm branch (3) respectively.

2. A self-locking circuit for current detection according to claim 1, characterized in that: The voltage of the current state signal State is 12V or 0V, and the voltage of the power input terminal Power is 12V.

3. The self-locking circuit for current detection according to claim 1, characterized in that: The current state signal State includes a normal current state signal and an abnormal current state signal, wherein the normal current state signal State is an analog voltage of 0V, and the abnormal current state signal State is an analog voltage of 12V; The current detection branch (1) comprises a current detection module (11), a diode D3 and a resistor R4; The positive electrode of the diode D3 is connected to the current detection module (11), and the negative electrode of the diode D3 is connected to the self-locking operation branch (2) and is grounded through the resistor R4.

4. The self-locking circuit for current detection according to claim 3, characterized in that: The current detection module (11) is a current transformer, the diode D3 is of type 1N4148, and the resistance of the resistor R4 is 10K.

5. The self-locking circuit for current detection according to claim 3, characterized in that: The self-locking operation branch (2) comprises a maintaining module (21), a self-locking module (22) and an operating module (23); One end of the maintaining module (21) is respectively connected to the cathode of the diode D3 and one end of the resistor R4, and the other end of the maintaining module (21) is respectively connected to one end of the self-locking module (22) and one end of the operating module (23); The other end of the operating module (23) is respectively connected to the power input terminal Power, the other end of the self-locking module (22) and the load alarm branch (3).

6. The self-locking circuit for current detection according to claim 5, characterized in that: The operation signal Action includes a normal working signal and a power-off alarm signal, wherein the normal working signal is a constant voltage of 0V and the power-off alarm signal is a constant voltage of 12V; The maintenance module (21) includes a resistor R1 and a capacitor C1; The self-locking module (22) includes a resistor R2, a resistor R6, a resistor R7, a diode D1, a transistor Q1, and a transistor Q5; The operating module (23) includes a resistor R3, a resistor R5, a transistor Q2, and a transistor Q3; One end of the resistor R1 is connected to the cathode of the diode D3 and one end of the resistor R4, and the other end of the resistor R1 is connected to the cathode of the diode D1, and is simultaneously connected to the base of the transistor Q5 through the resistor R6, is connected to the base of the transistor Q2 through the resistor R5, and is grounded through the capacitor C1; The emitter of the transistor Q5 is grounded, the collector of the transistor Q5 is connected to the base of the transistor Q1 through the resistor R2, and is respectively connected to the emitter of the transistor Q1, the power input terminal Power and the load alarm branch (3) through the resistor R7, and the collector of the transistor Q1 is connected to the positive electrode of the diode D1; The emitter of the transistor Q2 is grounded, the collector is connected to the base of the transistor Q3, and is respectively connected to the power input terminal Power and the load alarm branch (3) through the resistor R3. The collector of the transistor Q3 is connected to the load alarm branch (3), and the emitter of the transistor Q3 is grounded.

7. The self-locking circuit for current detection according to claim 6, characterized in that: The resistance of the resistor R1 is 510K, and the capacitor C1 is an aluminum capacitor with a capacitance of 100uF; The resistance of the resistor R2 is 10K, the resistance of the resistor R6 is 10K, the resistance of the resistor R7 is 100K, the model of the diode D1 is 1N4148, the model of the transistor Q1 is 9012, and the model of the transistor Q5 is 9013; The resistance of the resistor R3 is 3K, the resistance of the resistor R5 is 3K, the model of the transistor Q2 is 9013, and the model of the transistor Q3 is 9013.

8. The self-locking circuit for current detection according to claim 6, characterized in that: The load alarm branch (3) comprises a load module (31) and an alarm module (32); One end of the load module (31) is respectively connected to the power input terminal Power, the self-locking module (22) and the operating module (23), and the other end is respectively connected to the operating module (23) and the alarm module (32).

9. The self-locking circuit for current detection according to claim 8, characterized in that: The load module (31) includes a diode D2, a relay K1 and a load, wherein the relay K1 is provided with an input path and an output path; The alarm module (32) includes a relay K2, a speaker LS1 and a warning light DS1, wherein the relay K2 is provided with an input path and an output path; The cathode of the diode D2 is connected to the power input terminal Power, one end of the resistor R3, one end of the resistor R7, and the emitter of the transistor Q1, respectively; the anode of the diode D2 is connected to the collector of the transistor Q3; the input path of the relay K1 and the input path of the relay K2 are both connected in parallel with the diode D2; One end of the output path of the relay K1 is connected to the power input terminal Power, and the other end of the output path of the relay K1 is connected to the load Load; one end of the output path of the relay K2 is connected to the power input terminal Power, and the other end of the output path of the relay K2 is grounded through the speaker LS1 and the warning light DS1 respectively.

10. The self-locking circuit for current detection according to claim 9, characterized in that: The diode D2 is of model 1N4007, the relay K1 is a single-channel DC relay, and the relay K2 is a dual-channel DC relay.

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