Secondary side open circuit monitoring and protecting system of current transformer

Abstract

The invention provides a secondary side open circuit monitoring and protection system of a current transformer, which relates to the field of current transformers and comprises an open circuit monitoring module, an open circuit protection execution module, a signal output module and a monitoring terminal, in the real-time mode, when the secondary side loop of the current transformer has an open-circuit fault, the open-circuit monitoring module can quickly and accurately identify that the voltage value of the secondary side is abnormally increased, and once the voltage value exceeds a preset open-circuit voltage threshold value, a control signal is immediately output. The open circuit protection execution module responds to the control signal and automatically switches on a first wiring terminal and a second wiring terminal on the secondary side of the current transformer, so that a secondary side loop is effectively switched on again, potential safety hazards such as high-voltage discharge and rapid heating caused by open circuit are avoided, and an execution action signal is output at the same time. The system is also provided with a signal output module, and the signal output module can respond to an execution action signal and output an open circuit monitoring signal, thereby achieving the real-time monitoring of an open circuit fault.

Description

Technical Field

[0001] The present invention relates to the field of current transformers, and particularly to a secondary open - circuit monitoring and protection system for current transformers. Background Art

[0002] Currently, there is no on - line monitoring device for the operating state of high - voltage CT (current transformer), and there are the following defects:

[0003] When there is no on - line monitoring device for the operating state of high - voltage CT, if the secondary side suddenly opens, a high voltage will be formed. The exciting electromotive force changes suddenly from a very small value to a very large value. The magnetic flux in the iron core shows a severely saturated flat - top wave. The secondary winding will induce a very high spike wave when the magnetic flux passes through zero, and its value can reach several thousand or even tens of thousands of volts, endangering the safety of personnel and the insulation performance of instruments.

[0004] The open - circuit point may be the secondary terminal connection piece, an internal wire break and virtual connection in the line, forming a high - voltage discharge on both sides, generating heat rapidly in a short time. If not discovered and processed in time, in severe cases, it may cause a fire and trigger a switch cabinet explosion accident. Summary of the Invention

[0005] In view of this, the present invention aims to provide a secondary open - circuit monitoring and protection system for current transformers to solve the problem of the lack of open - circuit monitoring and protection on the secondary side of current transformers in the prior art.

[0006] To achieve the above object, the technical solution of the present invention is realized as follows:

[0007] The present invention provides a secondary open - circuit monitoring and protection system for current transformers, including:

[0008] An open - circuit monitoring module, an open - circuit protection execution module, a signal output module, and a monitoring terminal;

[0009] The open - circuit monitoring module is used to output a control signal when the secondary - side voltage of the current transformer is greater than a preset open - circuit voltage;

[0010] The open - circuit protection execution module, in response to the control signal, connects the first wiring terminal and the second wiring terminal of the secondary side of the current transformer and outputs an execution action signal;

[0011] The signal output module outputs an open - circuit monitoring signal in response to the execution action signal;

[0012] The monitoring terminal is used to obtain the open - circuit monitoring signal of the signal output module.

[0013] Furthermore, the open - circuit monitoring and protection system further includes an ammeter and a voltmeter;

[0014] The first terminal of the secondary side of the current transformer is connected to the current input terminal of the ammeter, the current output terminal of the ammeter is connected to the voltage input terminal of the voltmeter, and the voltage output terminal of the voltmeter is connected to the second terminal of the secondary side of the current transformer;

[0015] The monitoring terminal is further configured to obtain the current data collected by the ammeter and the voltage data collected by the voltmeter to determine whether there is an open circuit fault in the secondary side of the current transformer.

[0016] Furthermore, the open circuit monitoring and protection system further includes an analog-to-digital converter, and the analog input terminals of the analog-to-digital converter are respectively connected to the data output terminals of the voltmeter and the ammeter.

[0017] Furthermore, the open circuit monitoring module includes an overvoltage relay;

[0018] One end of the coil of the overvoltage relay is connected to the first terminal of the secondary side of the current transformer, and the other end is connected to the second terminal of the secondary side of the current transformer.

[0019] Furthermore, the secondary side open circuit monitoring and protection system further includes a first open circuit power supply; the open circuit protection execution module includes an open circuit protection execution relay;

[0020] The first end of the first open circuit power supply is connected to one end of the normally open contact of the overvoltage relay, and the other end of the normally open contact of the overvoltage relay is connected to one end of the coil of the open circuit protection execution relay; the other end of the coil of the open circuit protection execution relay is connected to the second end of the first open circuit power supply;

[0021] One end of the first normally open contact of the open circuit protection execution relay is connected to the first terminal of the secondary side of the current transformer, and the other end is connected to the second terminal of the secondary side of the current transformer.

[0022] Furthermore, the secondary side open circuit monitoring and protection system further includes a second open circuit power supply; the signal output module includes an open circuit signal relay;

[0023] The first end of the second open circuit power supply is connected to one end of the second normally open contact of the open circuit protection execution relay, the other end of the second normally open contact of the open circuit protection execution relay is connected to one end of the coil of the open circuit signal relay, and the other end of the coil of the open circuit signal relay is connected to the second end of the second open circuit power supply.

[0024] Furthermore, the secondary side open circuit monitoring and protection system further includes a communication management machine and a third open circuit power supply;

[0025] The first end of the third open - circuit power supply is connected to one end of the normally - open contact of the open - circuit signal relay, and the other end of the normally - open contact of the open - circuit signal relay is connected to the first digital input terminal of the communication management machine; the first common terminal of the communication management machine is connected to the second end of the third open - circuit power supply.

[0026] Further, the secondary - side open - circuit monitoring and protection system further includes an over - current relay;

[0027] One end of the coil of the over - current relay is connected to the first wiring terminal of the secondary side of the current transformer, and the other end is connected to the current input terminal of the ammeter;

[0028] The secondary - side open - circuit monitoring and protection system further includes a first over - current power supply and an alarm signal relay;

[0029] The first end of the first over - current power supply is connected to one end of the normally - open contact of the over - current relay, and the other end of the normally - open contact of the over - current relay is connected to one end of the coil of the alarm signal relay; the other end of the coil of the alarm signal relay is connected to the second end of the first over - current power supply;

[0030] The secondary - side open - circuit monitoring and protection system further includes a second over - current power supply and a communication management machine;

[0031] The first end of the second over - current power supply is connected to one end of the normally - open contact of the alarm signal relay, and the other end of the normally - open contact of the alarm signal relay is connected to the second digital input terminal of the communication management machine; the second common terminal of the communication management machine is connected to the second end of the second over - current power supply.

[0032] Further, the data receiving end of the communication management machine is also connected to the digital quantity output end of the analog - to - digital converter.

[0033] Further, the monitoring terminal is signal - connected to the network communication end of the communication management machine.

[0034] Compared with the prior art, the present invention has the following advantages:

[0035] In the present invention, when an open - circuit fault occurs in the secondary - side circuit of the current transformer, the open - circuit monitoring module can quickly and accurately identify that the secondary - side voltage value abnormally increases. Once this voltage value exceeds the preset open - circuit voltage threshold, a control signal is immediately output. Subsequently, the open - circuit protection execution module responds to this control signal, automatically connects the first wiring terminal and the second wiring terminal of the secondary - side of the current transformer, and simultaneously outputs an execution action signal, thereby effectively reconnecting the secondary - side circuit and avoiding safety hazards such as high - voltage discharge and rapid heating caused by the open - circuit. This process not only protects the safety of personnel but also ensures that the insulation performance of the instrument is not damaged. In addition, the present invention is also equipped with a signal output module, which can respond to the execution action signal and output an open - circuit monitoring signal. This signal can be captured by the monitoring terminal in real - time, enabling the operation and maintenance personnel to quickly know the open - circuit state of the secondary - side of the current transformer, and thus take corresponding maintenance measures in a timely manner.

[0036] Therefore, the present invention not only realizes the effective protection against the open - circuit fault of the secondary - side of the current transformer, but also improves the reliability and safety of the equipment through the online monitoring function, and reduces the risks of serious accidents such as fires and switchgear explosions caused by open - circuit faults. This is of great significance for improving the operation efficiency and safety of the high - voltage power system. BRIEF DESCRIPTION OF THE DRAWINGS

[0037] The drawings forming a part of the present invention are used to provide a further understanding of the present invention. The schematic embodiments of the present invention and their descriptions are used to explain the present invention and do not constitute an improper limitation of the present invention. In the drawings:

[0038] Figure 1 is the wiring circuit diagram when the secondary open - circuit fault does not occur in the current transformer of the present invention;

[0039] Figure 2 is the wiring circuit diagram when the secondary open - circuit fault occurs in the current transformer of the present invention;

[0040] Figure 3 is the overall circuit diagram of the present invention;

[0041] Figure 4 is the circuit diagram of the secondary - side open - circuit monitoring and protection system of the current transformer of the present invention. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0042] It should be noted that, without conflict, the embodiments in the present invention and the features in the embodiments can be combined with each other.

[0043] In the description of the present invention, it should be noted that the orientation or positional relationship indicated by the terms "upper", "lower", "inner", "back", etc. is based on the orientation or positional relationship shown in the drawings. It is only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore should not be construed as a limitation to the present invention. In addition, the terms "first" and "second" are only used for descriptive purposes and cannot be construed as indicating or implying relative importance.

[0044] In addition, in the description of the present invention, unless otherwise clearly defined, the terms "installation", "connection", "connection", "connector" should be understood in a broad sense. For example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be directly connected or indirectly connected through an intermediate medium, and it can be the communication inside two elements. For those of ordinary skill in the art, the specific meanings of the above terms in the present invention can be understood in combination with specific situations.

[0045] The following will refer to the attached Figures 1 to 4 and describe the present invention in detail in combination with embodiments.

[0046] Embodiment 1

[0047] Overall, when the CT operates normally, the secondary side provides the measuring current for the instrument, and the operating state of the device can be judged according to the magnitude of the current. When the secondary side is open-circuited, there is no current output on the secondary side, the instrument cannot detect the current, and various metering instruments and detection instruments all show errors. At the same time, a high voltage will be generated at the open-circuit point, and the voltage value can be as high as several thousand or even tens of thousands of volts. The open-circuit point discharges and generates sparks, causing the device to catch fire or even explode.

[0048] In a system with three phases A, B, and C, when the CT operates normally and there is no open circuit on the secondary side, taking phase C as an example, the wiring diagram after connecting the CT is as Figure 1 shown.

[0049] Figure 1 In the figure, A, B, and C are the respective phases in the three-phase system; E is the grounding point of the secondary side; I1 and I2 are the primary and secondary side currents respectively;

[0050] N1 and N2 respectively refer to the primary side and secondary side of the CT; A1, A2, etc. are the respective ammeters installed on the secondary side of the CT.

[0051] At this time, if the secondary side of the CT is open-circuited, a high voltage will be induced on the secondary side of the CT, burning out the terminal block, and in severe cases, it will cause a fire and the switch cabinet to explode. In the ABC three-phase system, taking phase C as an example, the wiring diagram after the CT connection is open-circuited is as Figure 2As shown in the figure. When a wire break accident occurs at point a, an arc is drawn at the wire break point, and the secondary current conducts through the arc, forming high temperature. At the same time, the voltage U12 between the two points reaches several thousand to 10,000 volts due to the open circuit.

[0052] The method for calculating the open circuit voltage on the secondary side of the CT is as follows:

[0053] Taking the secondary open circuit of a 1200 / 5A CT as an example, calculate the open circuit voltage.

[0054] The primary rated ampere-turns I1n = 1200A, N1n / N2n = 240, Ac = 25.5 cm 2 , Lc = 75.4 cm, f = 50 Hz, the iron core is made of cold-rolled silicon steel sheet, wound iron core, take K = 4.13×10 -2 , so the peak voltage of the secondary open circuit is:

[0055]

[0056] EKL is the secondary open circuit voltage (peak value), N2n is the rated secondary turns; Ac is the effective cross-sectional area of the iron core;

[0057] f is the power supply frequency, Hz; Lc is the average magnetic path length of the iron core; I1n is the rated primary current; N1n is the rated primary turns; K is a coefficient, related to the iron core material and iron core type, taking 4.13×10 for cold-rolled silicon steel sheet wound iron core -2 ; taking 2.59×10 for laminated iron core -2 ;

[0058] It can be seen that when the primary is operating normally, the secondary current of the CT is about 5 A. However, when it is open-circuited, the open-circuit peak voltage can reach 7.1 kV. Such a high voltage may cause damage to the longitudinal insulation of the current transformer and also pose a serious threat to the instruments on the secondary circuit.

[0059] Based on this, the present invention proposes the following technical solutions, specifically:

[0060] As Figure 3 and Figure 4 shown, the secondary open circuit monitoring and protection system of the current transformer includes:

[0061] An open circuit monitoring module, an open circuit protection execution module, a signal output module, and a monitoring terminal;

[0062] The open circuit monitoring module is used to output a control signal when the voltage on the secondary side of the current transformer is greater than the preset open circuit voltage;

[0063] The open circuit protection execution module, in response to the control signal, connects the first wiring terminal S1 and the second wiring terminal S2 on the secondary side of the current transformer and outputs an execution action signal;

[0064] A signal output module that outputs an open - circuit monitoring signal in response to an execution action signal;

[0065] A monitoring terminal for obtaining the open - circuit monitoring signal of the signal output module.

[0066] In the present invention, when an open - circuit fault occurs in the secondary side circuit of the current transformer, the open - circuit monitoring module can quickly and accurately identify that the secondary side voltage value abnormally increases. Once this voltage value exceeds the preset open - circuit voltage threshold, a control signal is immediately output. Subsequently, the open - circuit protection execution module responds to this control signal, automatically connects the first wiring terminal S1 and the second wiring terminal S2 of the secondary side of the current transformer, and simultaneously outputs an execution action signal, thereby effectively reconnecting the secondary side circuit and avoiding safety hazards such as high - voltage discharge and rapid heating caused by the open circuit. This process not only protects the safety of personnel but also ensures that the insulation performance of the instrument is not damaged. In addition, the present invention is also equipped with a signal output module that can output an open - circuit monitoring signal in response to the execution action signal. This signal can be captured by the monitoring terminal in real - time, enabling the operation and maintenance personnel to quickly know the open - circuit state of the secondary side of the current transformer, and thus take corresponding maintenance measures in a timely manner.

[0067] Therefore, the present invention not only realizes effective protection against open - circuit faults in the secondary side of the current transformer but also improves the reliability and safety of the equipment through the online monitoring function, reducing the risk of serious accidents such as fires and switchgear explosions caused by open - circuit faults. This is of great significance for improving the operation efficiency and safety of the high - voltage power system.

[0068] In a possible implementation manner, the open - circuit monitoring and protection system further includes an ammeter and a voltmeter;

[0069] The first wiring terminal S1 of the secondary side of the current transformer is connected to the current input end of the ammeter, the current output end of the ammeter is connected to the voltage input end of the voltmeter, and the voltage output end of the voltmeter is connected to the second wiring terminal S2 of the secondary side of the current transformer;

[0070] The monitoring terminal is further configured to obtain the current data collected by the ammeter and the voltage data collected by the voltmeter to determine whether there is an open - circuit fault in the secondary side of the current transformer.

[0071] In this embodiment, the monitoring terminal can calculate the real-time impedance of the current loop according to the ratio of the voltage data and the current data, and then calculate the resistance value of the loop on the secondary side of the current transformer. When the resistance value is greater than the preset threshold, it indicates that an open-circuit fault has occurred on the secondary side of the current transformer. At the same time, the monitoring terminal can obtain the current data of the secondary loop of the transformer collected by the ammeter, monitor the current change in real time, and generate a current change curve. Based on this curve, the open-circuit risk can be judged; the monitoring terminal can also obtain the voltage data of the secondary loop of the transformer collected by the voltmeter, monitor the voltage change in real time, and generate a voltage change curve. Based on this curve, the open-circuit risk can be judged.

[0072] In this embodiment, the voltmeter is preferably a digital voltmeter V, and the ammeter is preferably a digital ammeter A.

[0073] In this embodiment, the monitoring terminal further integrates multiple monitoring and analysis functions, significantly improving the accuracy and efficiency of the status monitoring of the secondary loop of the current transformer. By collecting voltage data and current data in real time and calculating their ratio to determine the real-time impedance of the current loop, and then accurately calculating the resistance value of the secondary loop of the current transformer, this mechanism provides strong technical support for timely discovering and warning of open-circuit faults. When the detected resistance value exceeds the preset threshold, the system can quickly identify the possible open-circuit fault on the secondary side of the current transformer, which reduces the safety hazards caused by the failure not being discovered in time. In addition, by monitoring the current change in real time and generating a current change curve, the monitoring terminal can judge whether there is an open-circuit risk based on the preset current threshold, further enhancing the early warning ability of the system. At the same time, the real-time monitoring of voltage data and the generation of voltage change curves enable the system to accurately evaluate the existence of open-circuit risks based on the preset voltage threshold, providing more comprehensive fault warning information for the operation and maintenance personnel. This method combining dual monitoring of current and voltage not only improves the accuracy of fault identification but also ensures the stable operation of the system under various working conditions.

[0074] In a possible implementation manner, the open-circuit monitoring and protection system further includes an analog-to-digital converter, and the analog input terminals of the analog-to-digital converter are respectively connected to the data output terminals of the voltmeter and the ammeter.

[0075] In a possible implementation manner, the open-circuit monitoring module includes an overvoltage relay KA1;

[0076] One end of the coil of the overvoltage relay KA1 is connected to the first terminal S1 of the secondary side of the current transformer, and the other end is connected to the second terminal S2 of the secondary side of the current transformer.

[0077] In a possible implementation, the secondary-side open-circuit monitoring and protection system further includes a first open-circuit power supply; the open-circuit protection execution module includes an open-circuit protection execution relay KM1;

[0078] The first end L11 of the first open-circuit power supply is connected to one end of the normally open contact of the overvoltage relay KA1, and the other end of the normally open contact of the overvoltage relay KA1 is connected to one end of the coil of the open-circuit protection execution relay KM1; the other end of the coil of the open-circuit protection execution relay KM1 is connected to the second end N11 of the first open-circuit power supply;

[0079] One end of the first normally open contact of the open-circuit protection execution relay KM1 is connected to the first wiring terminal S1 of the secondary side of the current transformer, and the other end is connected to the second wiring terminal S2 of the secondary side of the current transformer.

[0080] In a possible implementation, the secondary-side open-circuit monitoring and protection system further includes a second open-circuit power supply; the signal output module includes an open-circuit signal relay KS1;

[0081] The first end L12 of the second open-circuit power supply is connected to one end of the second normally open contact of the open-circuit protection execution relay KM1, the other end of the second normally open contact of the open-circuit protection execution relay KM1 is connected to one end of the coil of the open-circuit signal relay KS1, and the other end of the coil of the open-circuit signal relay KS1 is connected to the second end N12 of the second open-circuit power supply.

[0082] In a possible implementation, the secondary-side open-circuit monitoring and protection system further includes a communication management machine and a third open-circuit power supply;

[0083] The first end L13 of the third open-circuit power supply is connected to one end of the normally open contact of the open-circuit signal relay KS1, the other end of the normally open contact of the open-circuit signal relay KS1 is connected to the first digital input terminal of the communication management machine; the first common terminal of the communication management machine is connected to the second end N13 of the third open-circuit power supply.

[0084] In a possible implementation, the secondary-side open-circuit monitoring and protection system further includes an overcurrent relay KA2;

[0085] One end of the coil of the overcurrent relay KA2 is connected to the first wiring terminal S1 of the secondary side of the current transformer, and the other end is connected to the current input terminal of the ammeter;

[0086] The secondary-side open-circuit monitoring and protection system further includes a first overcurrent power supply and an alarm signal relay KS2;

[0087] One end of the first terminal L21 of the first overcurrent power supply is connected to one end of the normally open contact of the overcurrent relay KA2, and the other end of the normally open contact of the overcurrent relay KA2 is connected to one end of the coil of the alarm signal relay KS2; the other end of the coil of the alarm signal relay KS2 is connected to the second terminal N21 of the first overcurrent power supply;

[0088] The secondary side open circuit monitoring and protection system further includes a second overcurrent power supply and a communication management machine;

[0089] One end of the first terminal L22 of the second overcurrent power supply is connected to one end of the normally open contact of the alarm signal relay KS2, and the other end of the normally open contact of the alarm signal relay KS2 is connected to the second digital input terminal of the communication management machine; the second common terminal of the communication management machine is connected to the second terminal N22 of the second overcurrent power supply.

[0090] In a possible implementation manner, the data receiving end of the communication management machine is further connected to the digital quantity output end of the analog-to-digital converter.

[0091] In a possible implementation manner, the monitoring terminal is signal-connected to the network communication end of the communication management machine.

[0092] As Figure 4 shown, the working principle of the present invention is:

[0093] The current data of the ammeter and the voltage data of the voltmeter are acquired by the monitoring terminal through the analog-to-digital converter and the communication management machine.

[0094] The monitoring terminal calculates the real-time impedance of the current loop according to the ratio of the voltage data and the current data, and further calculates the resistance value of the loop on the secondary side of the current transformer. At the same time, the monitoring terminal can acquire the current data of the secondary loop of the transformer collected by the ammeter, monitor the current change in real time, and generate a current change curve. Based on this curve, the risk of open circuit can be judged; the monitoring terminal can also acquire the voltage data of the secondary loop of the transformer collected by the voltmeter, monitor the voltage change in real time, and generate a voltage change curve. Based on this curve, the risk of open circuit can be judged.

[0095] When the secondary side of the current transformer is open-circuited, the voltage between the first terminal S1 and the second terminal S2 of the secondary side of the current transformer rises rapidly. The voltage of the secondary side of the current transformer is greater than the preset open-circuit voltage. The coil of the overvoltage relay KA1 is energized and attracted. The normally open contact of the overvoltage relay KA1 closes to output a control signal, so that the coil of the open-circuit protection execution relay KM1 is energized and attracted. The first normally open contact of the open-circuit protection execution relay KM1 closes, so that the first terminal S1 and the second terminal S2 of the secondary side of the current transformer are connected, so as to avoid damage to the equipment caused by the open-circuit fault of the secondary side of the current transformer; at the same time, the second normally open contact of the open-circuit protection execution relay KM1 closes to output an execution action signal, so that the coil of the open-circuit signal relay KS1 is energized and attracted. The normally open contact of the open-circuit signal relay KS1 closes to output an open-circuit monitoring signal and is received by the communication management machine; the communication management machine sends the open-circuit monitoring signal to the monitoring terminal. The monitoring terminal further identifies whether there is an open-circuit fault on the secondary side of the current transformer according to the current voltage data, current data, and the calculated resistance value of the secondary side circuit of the current transformer. The multiple identification method enables the monitoring terminal to identify whether the overvoltage relay KA1 malfunctions.

[0096] On the other hand, when the secondary side of the current transformer is open-circuited, the voltage between the first terminal S1 and the second terminal S2 of the secondary side of the current transformer rises rapidly, which also causes the current in the circuit where the overcurrent relay KA2 is located to rise. The current on the secondary side of the current transformer is greater than the preset overcurrent value, and the coil of the overcurrent relay KA2 is energized and attracted; the normally open contact of the overcurrent relay KA2 closes, so that the coil of the alarm signal relay KS2 is energized and attracted. The normally open contact of the alarm signal relay KS2 closes to output an overcurrent signal and is received by the communication management machine. The communication management machine sends the overcurrent signal to the monitoring terminal. The monitoring terminal further determines the open-circuit condition of the secondary side of the current transformer according to the overcurrent signal.

[0097] The monitoring terminal significantly improves the accuracy and efficiency of the state monitoring of the secondary side circuit of the current transformer through multiple monitoring and analysis.

[0098] The above is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent replacements, improvements, etc. made within the spirit and principle of the present invention shall be included in the protection scope of the present invention.

Claims

1. A secondary side open circuit monitoring and protection system for a current transformer, characterized in that: include: Open circuit monitoring module, open circuit protection execution module, signal output module and monitoring terminal; The open circuit monitoring module is used to output a control signal when the secondary side voltage of the current transformer is greater than a preset open circuit voltage; The open circuit protection execution module, in response to the control signal, connects the first wiring terminal and the second wiring terminal of the secondary side of the current transformer and outputs an execution action signal; The signal output module outputs an open circuit monitoring signal in response to the execution action signal; The monitoring terminal is used to obtain the open circuit monitoring signal of the signal output module.

2. The secondary side open circuit monitoring and protection system of the current transformer according to claim 1, characterized in that: The open circuit monitoring and protection system also includes an ammeter and a voltmeter; The first terminal on the secondary side of the current transformer is connected to the current input terminal of the ammeter, the current output terminal of the ammeter is connected to the voltage input terminal of the voltmeter, and the voltage output terminal of the voltmeter is connected to the second terminal on the secondary side of the current transformer; The monitoring terminal is also used to obtain current data collected by the ammeter and voltage data collected by the voltmeter to determine whether there is an open circuit fault on the secondary side of the current transformer.

3. The secondary side open circuit monitoring and protection system of the current transformer according to claim 2, characterized in that: The open circuit monitoring and protection system further comprises an analog-to-digital converter, wherein the analog quantity input terminal of the analog-to-digital converter is respectively connected to the data output terminal of the voltmeter and the data output terminal of the ammeter.

4. The secondary side open circuit monitoring and protection system of the current transformer according to claim 3, characterized in that: The open circuit monitoring module includes an overvoltage relay; One end of the coil of the overvoltage relay is connected to the first wiring terminal on the secondary side of the current transformer, and the other end is connected to the second wiring terminal on the secondary side of the current transformer.

5. The secondary side open circuit monitoring and protection system of the current transformer according to claim 4, characterized in that: The secondary side open circuit monitoring and protection system further comprises a first open circuit power supply; the open circuit protection execution module comprises an open circuit protection execution relay; The first end of the first open circuit power supply is connected to one end of the normally open contact of the overvoltage relay, and the other end of the normally open contact of the overvoltage relay is connected to one end of the coil of the open circuit protection execution relay; the other end of the coil of the open circuit protection execution relay is connected to the second end of the first open circuit power supply; One end of the first normally open contact of the open circuit protection execution relay is connected to the first wiring terminal on the secondary side of the current transformer, and the other end is connected to the second wiring terminal on the secondary side of the current transformer.

6. The secondary side open circuit monitoring and protection system of the current transformer according to claim 5, characterized in that: The secondary side open circuit monitoring and protection system also includes a second open circuit power supply; the signal output module includes an open circuit signal relay; The first end of the second open-circuit power supply is connected to one end of the second normally open contact of the open-circuit protection execution relay, the other end of the second normally open contact of the open-circuit protection execution relay is connected to one end of the coil of the open-circuit signal relay, and the other end of the coil of the open-circuit signal relay is connected to the second end of the second open-circuit power supply.

7. The secondary side open circuit monitoring and protection system of the current transformer according to claim 6, characterized in that: The secondary side open circuit monitoring and protection system also includes a communication management machine and a third open circuit power supply; The first end of the third open-circuit power supply is connected to one end of the normally open contact of the open-circuit signal relay, and the other end of the normally open contact of the open-circuit signal relay is connected to the first digital input end of the communication management machine; the first common end of the communication management machine is connected to the second end of the third open-circuit power supply.

8. The secondary side open circuit monitoring and protection system of the current transformer according to claim 3, characterized in that: The secondary side open circuit monitoring and protection system also includes an overcurrent relay; One end of the coil of the overcurrent relay is connected to the first terminal of the secondary side of the current transformer, and the other end is connected to the current input terminal of the ammeter; The secondary side open circuit monitoring and protection system also includes a first overcurrent power supply and an alarm signal relay; The first end of the first overcurrent power supply is connected to one end of the normally open contact of the overcurrent relay, and the other end of the normally open contact of the overcurrent relay is connected to one end of the coil of the alarm signal relay; the other end of the coil of the alarm signal relay is connected to the second end of the first overcurrent power supply; The secondary side open circuit monitoring and protection system also includes a second overcurrent power supply and a communication management machine; The first end of the second overcurrent power supply is connected to one end of the normally open contact of the alarm signal relay, and the other end of the normally open contact of the alarm signal relay is connected to the second digital input end of the communication management machine; the second common end of the communication management machine is connected to the second end of the second overcurrent power supply.

9. The secondary side open circuit monitoring and protection system of the current transformer according to claim 7 or 8, characterized in that: The data receiving end of the communication management machine is also connected to the digital quantity output end of the analog-to-digital converter.

10. The secondary side open circuit monitoring and protection system of the current transformer according to claim 7 or 8, characterized in that: The monitoring terminal is signal-connected with the network communication terminal of the communication management machine.

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