Direct current insulation monitoring device
By using the main control module and positive and negative monitoring circuits of the DC insulation monitoring device, the problems of poor monitoring effect and stability of existing DC grounding detection devices are solved, achieving high accuracy and high sensitivity DC circuit monitoring and avoiding interference from AC signals to the system.
Patent Information
- Application Number
- CN202520242326.9
- Authority / Receiving Office
- CN · China
- Patent Type
- Utility models(China)
- Current Assignee / Owner
- Filing Date
- 2025-02-14
- Publication Date
- 2026-01-02
- Estimated Expiration
- 2035-02-14
AI Technical Summary
Existing DC grounding detection devices use outdated monitoring methods and have poor monitoring effects. Furthermore, the method of detecting grounding by injecting AC signals into branches or busbars can disrupt the stability of the DC system and affect the normal operation of the busbars.
A DC insulation monitoring device is adopted, including a main control module, a positive monitoring circuit, and a negative monitoring circuit. Through a circuit structure composed of components such as operational amplifiers and transistors, it can achieve accurate monitoring of DC circuits, avoid the injection of AC signals, and improve detection accuracy and sensitivity.
It improves the accuracy and sensitivity of DC circuit detection, reduces errors, avoids interference and aliasing, ensures the stability of DC systems, and makes the acquired signals more accurate, facilitating subsequent data processing.
Smart Images
Figure CN223756857U_ABST
Abstract
Description
TECHNICAL FIELD
[0001] The utility model relates to circuit monitoring technical field, concretely relates to a direct current insulation monitoring device. BACKGROUND
[0002] At present, the part direct current grounding detection device running in the direct current system of our country, is through setting the threshold value of balance bridge to carry out grounding detection. The detection method based on the principle of balance bridge, its essence is to utilize the balance condition of electric bridge to judge whether the direct current system is grounded and the grounding condition. However, in practical application, it has many defects difficult to overcome, because the running environment of direct current system is complex and changeable, is influenced by temperature, humidity, electromagnetic interference and various factors, the parameter of balance bridge is difficult to accurately set to the best state. This leads to in actual detection process, the threshold value set by the device and the actual grounding condition do not match completely, thereby influence the accuracy of detection result, and it also has the defects of big error and insensitivity, other monitoring methods have the mode of injecting alternating current signal on the branch or bus to carry out detection. Although this detection mode can realize the detection of direct current grounding to some extent, but also brings some new problems. Because the direct current system is a pure direct current power supply system itself, injecting alternating current signal can destroy the stability of direct current system, cause many aspects of influence to the bus. SUMMARY
[0003] The utility model to solve the technical problem that the existing direct current grounding detection device monitoring mode is backward, the monitoring effect is poor, and the method of injecting alternating current signal on the branch or bus to carry out detection can destroy the stability of direct current system and cause many aspects of influence to the bus.
[0004] In order to solve the above technical problems, the utility model adopts the following technical scheme: a direct current insulation monitoring device, including the main control module for data processing and overall circuit control, and the direct current monitoring module for monitoring the fault signal in direct current circuit, the direct current monitoring module includes positive pole monitoring circuit and negative pole monitoring circuit, the detection end of positive pole monitoring circuit is connected with the positive pole of direct current circuit, the control end of positive pole monitoring circuit is connected with main control module, the monitoring signal output end of positive pole monitoring circuit is connected with main control module, the detection end of negative pole monitoring circuit is connected with the negative pole of direct current circuit, the control end of negative pole monitoring circuit is connected with main control module, the monitoring signal output end of negative pole monitoring circuit is connected with main control module.
[0005] The utility model discloses a working time, can realize the monitoring of direct current circuit, compared to the method based on balance bridge threshold detection, can greatly improve the detection accuracy, can accurately sample direct current circuit, reduce the error of inaccurate parameter setting, also have higher sensitivity, the signal of subtle change in direct current circuit can also be detected in time, avoid the injection of alternating current signal, avoid the emergence of interference and aliasing, make the signal of collection more accurate, also convenient subsequent data processing.
[0006] As preferred, the positive electrode monitoring circuit comprises an operational amplifier U4, a transistor Q2, a transistor Q3, a diode DW3, a diode D4, a resistor R012, a resistor R014, a resistor R031, a resistor R032, a resistor R033, a resistor R034, a resistor R035, a resistor R041, a resistor R042, a resistor R045, a resistor R047, a resistor R049, a resistor R051, a resistor R110, a resistor R131, a resistor R132, a resistor R136, a capacitor C15, a capacitor C25, a capacitor C18 and a capacitor C65, a first end of the resistor R031 is connected with a positive electrode of a direct current circuit and a first end of a resistor R041, a second end of the resistor R031 is connected with a collector of the transistor Q2 through a resistor R032, a resistor R033, a resistor R034 and a resistor R035, an emitter of the transistor Q2 is connected with a collector of the transistor Q3, an emitter of the transistor Q3 is grounded, a base of the transistor Q3 is connected with a P1.3 port of a master control module through a resistor R132 and is grounded through a capacitor C25 and a resistor R110 respectively, the P1.3 port of the master control module is connected with a base of the transistor Q2 through a diode D4 and a resistor R131.
[0007] A second end of the resistor R041 is connected with a first end of a resistor R136 through a resistor R042, a resistor R045, a resistor R047, a resistor R049 and a resistor R051, the first end of the resistor R136 is grounded through a resistor R012, a second end of the resistor R136 is connected with a non-inverting input end of the operational amplifier U4 and is grounded through a capacitor C65, an inverting input end of the operational amplifier U4 is connected with an output end of the operational amplifier U4 and is grounded through a diode DW3, the output end of the operational amplifier U4 is connected with a first end of a resistor R142 and is grounded through a resistor R14, a second end of the resistor R142 is connected with a P1.0 port of the master control module and is grounded through a capacitor C15.
[0008] As preferred, the negative electrode monitoring circuit comprises transistor Q4, transistor Q5, transistor Q10, operational amplifier U5, diode D1, diode DW5, resistor R036, resistor R037, resistor R038, resistor R039, resistor R040, resistor R043, resistor R044, resistor R046, resistor R048, resistor R050, resistor R052, resistor R02, resistor R108, resistor R06, resistor R01, resistor R164, resistor R133, resistor R3053, resistor R3052, resistor R3051, resistor R304, resistor R451, resistor R452, resistor R141, capacitor C26 and capacitor C66, the first end of the resistor R036 is connected with the negative electrode of the direct current circuit and the first end of the resistor R043, the second end of the resistor R036 is connected with the collector of the transistor Q4 through the resistor R037, the resistor R038, the resistor R039 and the resistor R040, the emitter of the transistor Q4 is connected with the collector of the transistor Q5, the emitter of the transistor Q5 is grounded, the base of the transistor Q5 is connected with the first end of the resistor R133, the second end of the resistor R133 is connected with the collector of the transistor Q10 and grounded through the capacitor C26, the collector of the transistor Q10 is connected with the base of the transistor D4 through the diode D7 and the resistor R134, the collector of the transistor Q10 is connected with the power supply through the resistor R3053, the resistor R3052 and the resistor R3051 respectively and connected with the first end of the capacitor C18 through the resistor R3053, the resistor R3052 and the resistor R3051 respectively, the second end of the capacitor C18 is grounded, the emitter of the transistor Q10 is connected with the power supply, the base of the transistor Q10 is connected with the first end of the resistor R304, the second end of the resistor R304 is connected with the P1.4 port of the master control module and grounded through the resistor R451.
[0009] The second end of the resistor R043 is connected with the first end of the resistor R02 through the resistor R044, the resistor R046, the resistor R048, the resistor R050 and the resistor R052, the first end of the resistor R02 is connected with the anode of the diode D1, the cathode of the diode D1 is connected with the P1.2 port of the master control module and grounded through the resistor R108, the second end of the resistor R02 is connected with the inverting input end of the operational amplifier U5, the non-inverting input end of the operational amplifier U5 is grounded through the resistor R06, the inverting input end of the operational amplifier U5 is connected with the output end of the operational amplifier U5 through the resistor R01 and the capacitor C66 respectively, the output end of the operational amplifier U5 is connected with the P1.1 port of the master control module through the resistor R141 and grounded through the resistor R452 and the diode DW5 respectively.
[0010] As preferred, a communication module for serial port communication is further included, the main control module is in data connection with the communication module, and the main control module is in communication connection with the corresponding server through the communication module.
[0011] As preferred, a temperature monitoring module for monitoring temperature change is further included, the temperature monitoring module comprises a diode D10, a resistor R407, a resistor R408 and a capacitor C78, a P0.1 port of the main control module is connected with a first end of the resistor R408 and grounded through the capacitor C78, a second end of the resistor R408 is connected with the corresponding temperature sensor and connected with the power supply through the resistor R407, and the second end of the resistor R408 is grounded through the diode Z10.
[0012] As preferred, a protection module for protecting the circuit is further included, the protection module comprises a fuse F1, a capacitor CB1, a diode D22, a diode D21 and a resistor R11, a first end of the fuse F1 is connected with a first end of the power supply, a second end of the fuse is connected with the power supply and connected with the power supply through the resistor R11, the second end of the fuse F1 is connected with an anode of the diode D21 through the capacitor CB1 and the diode D22 respectively, the anode of the diode D21 is grounded, and a cathode of the diode D21 is connected with a second end of the power supply.
[0013] The beneficial technical effects of the utility model include:
[0014] The utility model discloses a monitoring device for direct current circuit, which comprises a main control module, a positive electrode detection circuit, a negative electrode detection circuit, a communication module and a protection module.
[0015] Other features and advantages of the utility model will be disclosed in detail in the following specific embodiments and drawings. BRIEF DESCRIPTION OF DRAWINGS
[0016] The utility model will be further explained in connection with the drawings:
[0017] Figure 1 It is a kind of direct current insulation monitoring device's structural schematic diagram;
[0018] Figure 2 It is the circuit structure diagram of main control module;
[0019] Figure 3 It is the circuit structure diagram of positive electrode detection circuit;
[0020] Figure 4 Circuit structure diagram for negative electrode monitoring circuit;
[0021] Figure 5 Circuit structure diagram for communication module;
[0022] Figure 6 Circuit structure diagram for temperature monitoring module and protection module. DETAILED DESCRIPTION
[0023] The technical solutions of the embodiments of the utility model will be explained and described below in combination with the drawings of the embodiments of the utility model. However, the following embodiments are only preferred embodiments of the utility model, and not all. Based on the embodiments in the embodiments, other embodiments obtained by those skilled in the art without creative labor belong to the protection scope of the utility model.
[0024] In the following description, the appearance of terms such as 'in', 'out', 'up', 'down', 'left', 'right' and the like indicates the orientation or positional relationship only for the convenience of describing the embodiments and simplifying the description, and does not indicate or imply that the device or element referred to must have a particular orientation, be constructed and operated in a particular orientation, and therefore cannot be understood as a limitation on the utility model.
[0025] Please refer to Figure 1 The embodiment discloses a direct current insulation monitoring device, comprising a master control module 1 for data processing and overall circuit control, and a direct current monitoring module 2 for monitoring fault signals in a direct current circuit, which will be described in detail below in combination with the drawings.
[0026] Please refer to Figures 1 to 6 In the embodiment, the direct current monitoring module 2 comprises a positive electrode monitoring circuit 21 and a negative electrode monitoring circuit 22, the detection end of the positive electrode monitoring circuit 21 is connected with the positive electrode of the direct current circuit, the control end of the positive electrode monitoring circuit 21 is connected with the master control module 1, the monitoring signal output end of the positive electrode monitoring circuit 21 is connected with the master control module 1, the detection end of the negative electrode monitoring circuit 22 is connected with the negative electrode of the direct current circuit, the control end of the negative electrode monitoring circuit 22 is connected with the master control module 1, and the monitoring signal output end of the negative electrode monitoring circuit 22 is connected with the master control module 1.
[0027] When the embodiment works, the monitoring of the direct current circuit can be realized, compared with the method based on the balance bridge threshold value detection, the detection accuracy can be greatly improved, the direct current circuit can be accurately sampled, the error caused by inaccurate parameter setting can be reduced, and the sensitivity is high, the subtle change signal in the direct current circuit can also be detected in time, the injection of the alternating current signal is avoided, the interference and aliasing are avoided, the collected signal is more accurate, and the subsequent data processing is also convenient.
[0028] In the implementation, the positive electrode monitoring circuit 21 comprises an operational amplifier U4, a transistor Q2, a transistor Q3, a diode DW3, a diode D4, a resistor R012, a resistor R014, a resistor R031, a resistor R032, a resistor R033, a resistor R034, a resistor R035, a resistor R041, a resistor R042, a resistor R045, a resistor R047, a resistor R049, a resistor R051, a resistor R110, a resistor R131, a resistor R132, a resistor R136, a resistor R142, a capacitor C15, a capacitor C25, a capacitor C18 and a capacitor C65. A first end of the resistor R031 is connected with a positive electrode of a direct current circuit and a first end of the resistor R041, a second end of the resistor R031 is connected with a collector of the transistor Q2 through the resistor R032, the resistor R033, the resistor R034 and the resistor R035, an emitter of the transistor Q2 is connected with a collector of the transistor Q3, an emitter of the transistor Q3 is grounded, a base of the transistor Q3 is connected with a P1.3 port of the master control module 1 through the resistor R132 and is grounded through the capacitor C25 and the resistor R110 respectively, and the P1.3 port of the master control module 1 is connected with a base of the transistor Q2 through the diode D4 and the resistor R131.
[0029] A second end of the resistor R041 is connected with a first end of the resistor R136 through the resistor R042, the resistor R045, the resistor R047, the resistor R049 and the resistor R051, the first end of the resistor R136 is grounded through the resistor R012, a second end of the resistor R136 is connected with a non-inverting input end of the operational amplifier U4 and is grounded through the capacitor C65, an inverting input end of the operational amplifier U4 is connected with an output end of the operational amplifier U4 and is grounded through the diode DW3, the output end of the operational amplifier U4 is connected with a first end of the resistor R142 and is grounded through the resistor R14, a second end of the resistor R142 is connected with a P1.0 port of the master control module 1 and is grounded through the capacitor C15, further voltage division and voltage adjustment are performed through a voltage division network, and a corresponding high or low level signal is output through voltage detection and comparison, so that the monitoring function of the direct current circuit is realized.
[0030] In the implementation, the negative electrode monitoring circuit 22 comprises a transistor Q4, a transistor Q5, a transistor Q10, an operational amplifier U5, a diode D1, a diode DW5, a resistor R036, a resistor R037, a resistor R038, a resistor R039, a resistor R040, a resistor R043, a resistor R044, a resistor R046, a resistor R048, a resistor R050, a resistor R052, a resistor R02, a resistor R108, a resistor R06, a resistor R01, a resistor R164, a resistor R133, a resistor R3053, a resistor R3052, a resistor R3051, a resistor R304, a resistor R451, a resistor R452, a capacitor C26, and a capacitor C66. A first end of the resistor R036 is connected to a negative electrode of a direct current circuit and connected to a first end of the resistor R043. A second end of the resistor R036 is connected to a collector of the transistor Q4 through the resistor R037, the resistor R038, the resistor R039, and the resistor R040. An emitter of the transistor Q4 is connected to a collector of the transistor Q5. An emitter of the transistor Q5 is grounded. A base of the transistor Q5 is connected to a first end of the resistor R133. A second end of the resistor R133 is connected to a collector of the transistor Q10 and grounded through a capacitor C26. The collector of the transistor Q10 is connected to a base of the transistor D4 through a diode D7 and a resistor R134. The collector of the transistor Q10 is connected to a power supply through the resistor R3053, the resistor R3052, and the resistor R3051 respectively and connected to a first end of a capacitor C18 through the resistor R3053, the resistor R3052, and the resistor R3051 respectively. A second end of the capacitor C18 is grounded. An emitter of the transistor Q10 is connected to the power supply. A base of the transistor Q10 is connected to a first end of the resistor R304. A second end of the resistor R304 is connected to a P1.4 port of the main control module 1 and grounded through a resistor R451.
[0031] A second end of the resistor R043 is connected to a first end of the resistor R02 through the resistor R044, the resistor R046, the resistor R048, the resistor R050, and the resistor R052. The first end of the resistor R02 is connected to an anode of the diode D1. A cathode of the diode D1 is connected to a P1.2 port of the main control module 1 and grounded through a resistor R108. A second end of the resistor R02 is connected to an inverting input end of the operational amplifier U5. A non-inverting input end of the operational amplifier U5 is grounded through a resistor R06. The inverting input end of the operational amplifier U5 is connected to an output end of the operational amplifier U5 through a resistor R01 and a capacitor C66 respectively. The output end of the operational amplifier U5 is connected to a P1.1 port of the main control module 1 through a resistor R141 and grounded through a resistor R452 and a diode DW5 respectively.
[0032] Preferably, it further comprises a communication module 3 for serial communication, the main control module 1 is in data connection with the communication module 3, and the main control module 1 is in communication connection with the corresponding server through the communication module 3, please refer to the attached Figure 3 In the specific implementation, the 485 communication module 3 can be used to realize the serial communication, and of course, the Bluetooth module or the Internet of Things module can be changed according to the actual application environment.
[0033] As a further improvement of the embodiment, it further comprises a temperature monitoring module 4 for monitoring temperature change, the temperature monitoring module 4 comprises a diode D10, a resistor R407, a resistor R408 and a capacitor C78, the P0.1 port of the main control module 1 is connected with the first end of the resistor R408 and grounded through the capacitor C78, the second end of the resistor R408 is connected with the corresponding temperature sensor and connected with the power supply through the resistor R407, the second end of the resistor R408 is grounded through the diode Z10, which facilitates temperature monitoring, can improve the safety factor to a certain extent and prolong the service life.
[0034] Preferably, it further comprises a protection module 5 for protecting the circuit, the protection module 5 comprises a fuse F1, a capacitor CB1, a diode D22, a diode D21 and a capacitor R11, the first end of the fuse F1 is connected with the first end of the power supply, the second end of the fuse is supplied with the power supply and supplied with the power supply through the resistor R11, the second end of the fuse F1 is connected with the anode of the diode D21 through the capacitor CB1 and the diode D22 respectively, the anode of the diode D21 is grounded, and the cathode of the diode D21 is connected with the second end of the power supply, which can protect the circuit in the overcurrent state.
[0035] The beneficial technical effects of the embodiment include that the utility model can realize the monitoring of the direct current circuit, compared with the method based on the balance bridge threshold value detection, the detection accuracy can be greatly improved, the direct current circuit can be accurately sampled, the error caused by inaccurate parameter setting is reduced, and the utility model has high sensitivity, the signal with slight change in the direct current circuit can also be detected in time, the injection of the alternating current signal is avoided, the interference and aliasing are avoided, the collected signal is more accurate, and the subsequent data processing is facilitated.
[0036] The above is only a specific implementation of the utility model, but the protection scope of the utility model is not limited to this, and those skilled in the art should understand that the utility model includes but is not limited to the contents described in the drawings and the above specific implementation. Any modification without deviating from the function and structural principle of the utility model will be included in the scope of claims.
Claims
1. A DC insulation monitoring device, characterized by: The application relates to a DC monitoring module (2) for monitoring fault signals in a DC circuit, comprising a positive electrode monitoring circuit (21) and a negative electrode monitoring circuit (22), wherein the detection end of the positive electrode monitoring circuit (21) is connected with the positive electrode of the DC circuit, the control end of the positive electrode monitoring circuit (21) is connected with a master control module (1), the monitoring signal output end of the positive electrode monitoring circuit (21) is connected with the master control module (1), the detection end of the negative electrode monitoring circuit (22) is connected with the negative electrode of the DC circuit, the control end of the negative electrode monitoring circuit (22) is connected with the master control module (1), and the monitoring signal output end of the negative electrode monitoring circuit (22) is connected with the master control module (1).
2. A DC insulation monitoring device according to claim 1, characterized in that The positive electrode monitoring circuit (21) comprises an operational amplifier U4, a triode Q2, a triode Q3, a diode DW3, a diode D4, a resistor R012, a resistor R014, a resistor R031, a resistor R032, a resistor R033, a resistor R034, a resistor R035, a resistor R041, a resistor R042, a resistor R045, a resistor R047, a resistor R049, a resistor R051, a resistor R110, a resistor R131, a resistor R132, a resistor R136, a resistor R142, a capacitor C15, a capacitor C25, a capacitor C18 and a capacitor C65, the first end of the resistor R031 is connected with the positive electrode of the DC circuit and the first end of the resistor R041, the second end of the resistor R031 is connected with the collector of the triode Q2 through the resistor R032, the resistor R033, the resistor R034 and the resistor R035, the emitter of the triode Q2 is connected with the collector of the triode Q3, the emitter of the triode Q3 is grounded, the base of the triode Q3 is connected with the P1.3 port of the master control module (1) through the resistor R132 and is grounded through the capacitor C25 and the resistor R110 respectively, and the P1.3 port of the master control module (1) is connected with the base of the triode Q2 through the diode D4 and the resistor R131; the second end of the resistor R041 is connected with the first end of the resistor R136 through the resistor R042, the resistor R045, the resistor R047, the resistor R049 and the resistor R051, the first end of the resistor R136 is grounded through the resistor R012, the second end of the resistor R136 is connected with the non-inverting input end of the operational amplifier U4 and is grounded through the capacitor C65, the inverting input end of the operational amplifier U4 is connected with the output end of the operational amplifier U4 and is grounded through the diode DW3, the output end of the operational amplifier U4 is connected with the first end of the resistor R142 and is grounded through the resistor R14, and the second end of the resistor R142 is connected with the P1.0 port of the master control module (1) and is grounded through the capacitor C15.
3. A DC insulation monitoring device according to claim 2, characterized in that The negative electrode monitoring circuit (22) comprises a transistor Q4, a transistor Q5, a transistor Q10, an operational amplifier U5, a diode D1, a diode DW5, a resistor R036, a resistor R037, a resistor R038, a resistor R039, a resistor R040, a resistor R043, a resistor R044, a resistor R046, a resistor R048, a resistor R050, a resistor R052, a resistor R02, a resistor R108, a resistor R06, a resistor R01, a resistor R164, a resistor R133, a resistor R3053, a resistor R3052, a resistor R3051, a resistor R304, a resistor R451, a resistor R452, a resistor R141, a capacitor C26 and a capacitor C66, a first end of the resistor R036 is connected with a negative electrode of a direct current circuit and a first end of a resistor R043, a second end of the resistor R036 is connected with a collector of the transistor Q4 through a resistor R037, a resistor R038, a resistor R039 and a resistor R040, an emitter of the transistor Q4 is connected with a collector of the transistor Q5, an emitter of the transistor Q5 is grounded, a base of the transistor Q5 is connected with a first end of a resistor R133, a second end of the resistor R133 is connected with a collector of the transistor Q10 and grounded through a capacitor C26, the collector of the transistor Q10 is connected with a base of a transistor D4 through a diode D7 and a resistor R134, the collector of the transistor Q10 is connected with a power supply through a resistor R3053, a resistor R3052 and a resistor R3051 respectively and connected with a first end of a capacitor C18 through a resistor R3053, a resistor R3052 and a resistor R3051 respectively, a second end of the capacitor C18 is grounded, an emitter of the transistor Q10 is connected with the power supply, a base of the transistor Q10 is connected with a first end of a resistor R304, a second end of the resistor R304 is connected with a P1.4 port of the master control module (1) and grounded through a resistor R451; a second end of the resistor R043 is connected with a first end of a resistor R02 through a resistor R044, a resistor R046, a resistor R048, a resistor R050 and a resistor R052, the first end of the resistor R02 is connected with an anode of a diode D1, a cathode of the diode D1 is connected with a P1.2 port of the master control module (1) and grounded through a resistor R108, a second end of the resistor R02 is connected with an inverting input end of the operational amplifier U5, a non-inverting input end of the operational amplifier U5 is grounded through a resistor R06, the inverting input end of the operational amplifier U5 is connected with an output end of the operational amplifier U5 through a resistor R01 and a capacitor C66 respectively, the output end of the operational amplifier U5 is connected with a P1.1 port of the master control module (1) through a resistor R141 and grounded through a resistor R452 and a diode DW5 respectively.
4. A DC insulation monitoring device according to claim 1, characterized in that The communication module (3) for serial port communication is further included, the master control module (1) is data connected with the communication module (3), and the master control module (1) is in communication connection with a corresponding server through the communication module (3).
5. A DC insulation monitoring device according to claim 1, characterized in that Also included is a temperature monitoring module (4) for monitoring temperature changes, the temperature monitoring module (4) comprising a diode D10, a resistor R407, a resistor R408 and a capacitor C78, the P0.1 port of the main control module (1) being connected to the first end of the resistor R408 and grounded through the capacitor C78, the second end of the resistor R408 being connected to the corresponding temperature sensor and to the power supply through the resistor R407, the second end of the resistor R408 being grounded through the diode Z10.
6. A DC insulation monitoring device according to claim 1, characterized in that Also included is a protection module (5) for protecting the circuit, the protection module (5) comprising a fuse F1, a capacitor CB1, a diode D22, a diode D21 and a resistor R11, the first end of the fuse F1 being connected to the first end of the power supply, the second end of the fuse being supplied to the power supply and to the power supply through the resistor R11, the second end of the fuse F1 being connected to the anode of the diode D21 through the capacitor CB1 and the diode D22 respectively, the anode of the diode D21 being grounded, the cathode of the diode D21 being connected to the second end of the power supply.