CT open circuit overtemperature protection device
By designing the CT open-circuit overtemperature protection device, the cooperation of the open-circuit detection module and the temperature detection module and the protection circuit, the high voltage problem caused by the open-circuit current transformer is solved, and effective protection of the current transformer is achieved to ensure safe operation and reduce risks.
Patent Information
- Application Number
- CN202520059890.7
- Authority / Receiving Office
- CN · China
- Patent Type
- Utility models(China)
- Current Assignee / Owner
- Filing Date
- 2025-01-10
- Publication Date
- 2025-03-07
- Estimated Expiration
- 2035-01-10
AI Technical Summary
In the prior art, current transformers may cause high voltage when open circuit, resulting in economic losses and personnel safety hazards.
Design a CT open circuit overtemperature protection device, including a power supply circuit, a current transformer and a protection circuit. The voltage and temperature of the current transformer are monitored through the connection between the open circuit detection module and the temperature detection module and the protection circuit. When the threshold value is exceeded, the pin of the current transformer is short-circuited through the MOS tube to avoid high voltage.
Effectively prevent high voltage from being generated by open circuit of current transformers, ensure safe operation of equipment, reduce economic losses and personnel safety risks, and at the same time, the protection circuit is simple, low cost and fast reaction speed.
Smart Images
Figure CN222582050U_ABST
Abstract
Description
Technical Field
[0001] The utility model relates to the technical field of electric power, in particular to a CT open circuit over-temperature protection device. Background Art
[0002] The current transformer is an important electrical equipment. It uses the principle of electromagnetic induction to convert the large current on the primary side into a small current on the secondary side, so as to measure, protect and control the operation of the system. When the current transformer is working, its secondary circuit is always closed. This is because if the secondary circuit is open, it may cause high voltage electricity, damage the equipment, and in serious cases, cause a fire, endangering the personal safety of personnel. Therefore, it is necessary to take protective measures for the current transformer to avoid accidents. Utility Model Content
[0003] In view of the problems existing in the prior art, the utility model proposes a CT open circuit over-temperature protection device, which is intended to prevent the current transformer from opening and generating high voltage, thereby avoiding economic damage and endangering personnel safety.
[0004] To achieve the above-mentioned purpose, the technical solution adopted by the utility model is: a CT open circuit over-temperature protection device, which includes a power supply circuit, a current transformer and a protection circuit, the power supply circuit is connected to the current transformer through a wiring terminal, each group of positive ports and negative ports of the power supply circuit are connected to the protection circuit, the current transformer is provided with an open circuit detection module and a temperature detection module, the open circuit detection module and the temperature detection module are connected to the protection circuit, the protection circuit includes a first MOS tube, a second MOS tube, a first resistor, a first capacitor and a variable resistor, the gates of the first MOS tube and the second MOS tube are connected to the control signal port, one end of the first resistor and the variable resistor are connected to the drain of the first MOS tube, the other end of the first resistor is connected to one end of the first capacitor, one end of the first capacitor and the other end of the variable resistor are connected to the drain of the second MOS tube, and the source of the first MOS tube and the second MOS tube are grounded.
[0005] Furthermore, the power supply circuit is connected in parallel with three groups of rectifier bridges, the third pins of the three groups of rectifier bridges are all connected to the working voltage and the fourth pins are all grounded, and the rectifier bridges are respectively connected to the corresponding wiring ports of the wiring terminals through the positive port and the negative port.
[0006] Furthermore, the temperature detection module includes a sixth resistor and a thermistor, one end of the thermistor is grounded, one end of the sixth resistor is connected to the third signal port of the integrated circuit, and the other ends of the sixth resistor and the thermistor are both connected to the eleventh signal port of the integrated circuit. When the temperature detection module detects that the temperature of the current transformer exceeds a threshold value, the pin of the current transformer is short-circuited with the ground wire through the MOS tube, so that the current transformer stops working.
[0007] In summary, the open circuit detection module and the temperature detection module monitor the voltage of the current transformer. When the line voltage in the current transformer is detected to exceed the reference base value, it indicates that the current transformer has been disconnected and opened. At this time, the first MOS tube and the second MOS tube in the corresponding protection circuit are turned on, and the corresponding positive port and negative port in the power supply circuit are short-circuited to avoid the safety hazard caused by the high voltage generated by the open circuit of the current transformer. At the same time, the temperature detection module performs temperature detection on the current transformer. When the temperature value detected is greater than the set threshold, it indicates that the current transformer has been overloaded and has serious heat. At this moment, the first MOS tube and the second MOS tube in the corresponding protection circuit are turned on, and the corresponding positive port and negative port in the power supply circuit are short-circuited, and the current transformer stops working. When the temperature value is lower than the threshold, the first MOS tube and the second MOS tube are automatically disconnected, and the current transformer works normally, which plays a role in over-temperature and overload protection of the current transformer.
[0008] The beneficial effects of the utility model are as follows: the temperature and open circuit state of the current transformer are detected by the temperature detection module and the open circuit detection module, and the over-temperature and open circuit of the current transformer are protected and controlled by the first MOS tube and the second MOS tube of the protection circuit, thereby realizing the protection of the current transformer. In addition, the circuit principle of the protection circuit is simple, and the required electronic components are few, so it has the characteristics of fast response speed and low production cost. At the same time, a variable resistor is provided in the protection circuit, and different voltage divider ratios are obtained by adjusting the resistance value of the variable resistor, thereby adjusting the thresholds of the first MOS tube and the second MOS tube, thereby improving the versatility of the protection circuit.
[0009] In order to more clearly illustrate the above features of the present invention and the objectives to be achieved, the present invention is further described below in conjunction with the accompanying drawings and specific embodiments. BRIEF DESCRIPTION OF THE DRAWINGS
[0010] Figure 1 : It is the circuit schematic diagram of the power supply circuit and the current transformer;
[0011] Figure 2: Circuit schematic diagram for protection circuit;
[0012] Figure 3 : This is the circuit schematic diagram of the open circuit detection module;
[0013] Figure 4 : It is the circuit schematic diagram of the temperature detection module;
[0014] Figure 5 : It is the overall principle block diagram of the utility model. DETAILED DESCRIPTION
[0015] like Figures 1 to 5 As shown, a CT open circuit over-temperature protection device includes a power supply circuit L1, current transformers CT1, CT2, CT3 and a protection circuit. The power supply circuit L1 is connected to the current transformers CT1, CT2, CT3 through a wiring terminal J1. The protection circuit L2 is connected between each group of positive ports UIN2, UIN4, UIN6 and negative ports UIN1, UIN3, UIN5 of the power supply circuit L1. The current transformers CT1, CT2, CT3 are provided with an open circuit detection module U1 and a temperature detection module U2. The open circuit detection module U1 and the temperature detection module U2 are both connected to the protection circuit L2.
[0016] The power supply circuit L1 is connected in parallel with three groups of rectifier bridges D1, D2, and D3. The third pins of the three groups of rectifier bridges D1, D2, and D3 are all connected to the working voltage VDD and the fourth pins are all grounded. The rectifier bridges D1, D2, and D3 are respectively connected to the corresponding wiring ports of the wiring terminal J1 through the positive ports UIN2, UIN4, and UIN6 and the negative ports UIN1, UIN3, and UIN5.
[0017] The protection circuit L2 includes a first MOS transistor Q1, a second MOS transistor Q2, a first resistor R1, a first capacitor C1 and a variable resistor RV1. The gates of the first MOS transistor Q1 and the second MOS transistor Q2 are both connected to the control signal port, one end of the first resistor R1 and the variable resistor RV1 are connected to the drain of the first MOS transistor Q1, the other end of the first resistor R1 is connected to one end of the first capacitor C1, one end of the first capacitor C1 and the other end of the variable resistor RV1 are connected to the drain of the second MOS transistor Q2, and the sources of the first MOS transistor Q1 and the second MOS transistor Q2 are both grounded.
[0018] The temperature detection module U2 includes a sixth resistor R6 and a thermistor RT1, one end of the thermistor RT1 is grounded, one end of the sixth resistor R6 is connected to the third signal port of the integrated circuit, and the other end of the sixth resistor R6 and the other end of the thermistor RT1 are both connected to the eleventh signal port of the integrated circuit.
[0019] To sum up, the open circuit detection module U1 and the temperature detection module U2 monitor the voltage of the current transformers CT1, CT2, and CT3. When it is monitored that the line voltage in the current transformers CT1, CT2, and CT3 exceeds the reference base value, it means that the current transformers CT1, CT2, and CT3 are disconnected and open-circuited. At this time, the first MOS tube Q1 and the second MOS tube Q2 in the corresponding protection circuit L2 are turned on, and the corresponding positive ports UIN2, UIN4, and UIN6 in the power supply circuit L1 are short-circuited with the negative ports UIN1, UIN3, and UIN5 to achieve the safety purpose of protecting electricity. At the same time, the temperature detection module U2 performs temperature detection on the current transformers CT1, CT2, and CT3. When the detected temperature value is greater than the set threshold, it indicates that the current transformers CT1, CT2, and CT3 are overloaded and have serious heating. At this moment, the first MOS tube Q1 and the second MOS tube Q2 in the corresponding protection circuit L2 are turned on, and the corresponding positive ports UIN2, UIN4, and UIN6 in the power supply circuit L1 are short-circuited with the negative ports UIN1, UIN3, and UIN5, and the current transformers CT1, CT2, and CT3 stop working. When the temperature value is lower than the threshold, the first MOS tube Q1 and the second MOS tube Q2 are automatically disconnected, and the current transformers CT1, CT2, and CT3 work normally.
[0020] The specific implementation method of this embodiment is as follows: the open circuit detection module U1 monitors the voltage of the current transformers CT1, CT2, and CT3. When it is detected that the line voltage in the current transformers CT1, CT2, and CT3 exceeds the reference base value, it indicates that the current transformers CT1, CT2, and CT3 are disconnected and open-circuited. At this time, the first MOS tube Q1 and the second MOS tube Q2 in the corresponding protection circuit L2 are internally turned on, and the corresponding positive ports UIN2, UIN4, and UIN6 in the power supply circuit L1 are short-circuited with the negative ports UIN1, UIN3, and UIN5. After the short-circuit, the corresponding current transformers CT1, CT2, and CT3 stop working, thereby achieving the safety purpose of protecting electricity use. At the same time, the temperature detection module U2 performs temperature detection on the current transformers CT1, CT2, and CT3. When the detected temperature value is greater than the set threshold, it indicates that the current transformers CT1, CT2, and CT3 are overloaded and have serious fever. At this moment, the first MOS tube Q1 and the second MOS tube Q2 in the corresponding protection circuit L2 are internally turned on, and the corresponding positive ports UIN2, UIN4, and UIN6 in the power supply circuit L1 are short-circuited with the negative ports UIN1, UIN3, and UIN5, and the current transformers CT1, CT2, and CT3 stop working. When the temperature value is lower than the threshold, the first MOS tube Q1 and the second MOS tube Q2 are automatically disconnected, and the current transformers CT1, CT2, and CT3 work normally.
[0021] The above description is only the optimal solution embodiment of the present invention and is not intended to limit the present invention. Various modifications or substitutions made to the present invention by those skilled in the art without departing from the essence and protection scope of the present invention should also be within the protection scope of the present invention.
Claims
1. A CT open circuit over-temperature protection device, comprising a power supply circuit (L1), a current transformer (CT1, CT2, CT3) and a protection circuit (L2), characterized in that: The power supply circuit (L1) is connected to the current transformer (CT1, CT2, CT3) via a wiring terminal (J1); each group of positive ports (UIN2, UIN4, UIN6) and negative ports (UIN1, UIN3, UIN5) of the power supply circuit (L1) are connected to the protection circuit (L2); the current transformers (CT1, CT2, CT3) are each provided with an open circuit detection module (U1) and a temperature detection module (U2); the open circuit detection module (U1) and the temperature detection module (U2) are both connected to the protection circuit (L2); the protection circuit (L2) includes a first MOS tube (Q1), a second MOS tube (Q2); An MOS tube (Q2), a first resistor (R1), a first capacitor (C1) and a variable resistor (RV1), the gates of the first MOS tube (Q1) and the second MOS tube (Q2) are both connected to a control signal port, one end of the first resistor (R1) and the variable resistor (RV1) are connected to the drain of the first MOS tube (Q1), the other end of the first resistor (R1) is connected to one end of the first capacitor (C1), one end of the first capacitor (C1) and the other end of the variable resistor (RV1) are both connected to the drain of the second MOS tube (Q2), and the sources of the first MOS tube (Q1) and the second MOS tube (Q2) are both grounded.
2. A CT open circuit over-temperature protection device according to claim 1, characterized in that: The power supply circuit (L1) is connected in parallel with three groups of rectifier bridges (D1, D2, D3), the third pins of the three groups of rectifier bridges (D1, D2, D3) are all connected to the working voltage (VDD) and the fourth pins are all grounded, and the rectifier bridges (D1, D2, D3) are respectively connected to the corresponding wiring ports of the wiring terminal (J1) through the positive port (UIN2, UIN4, UIN6) and the negative port (UIN1, UIN3, UIN5).
3. A CT open circuit over-temperature protection device according to claim 1, characterized in that: The temperature detection module (U2) comprises a sixth resistor (R6) and a thermistor (RT1), one end of the thermistor (RT1) is grounded, one end of the sixth resistor (R6) is connected to a third signal port of the integrated circuit, and the other end of the sixth resistor (R6) and the other end of the thermistor (RT1) are both connected to an eleventh signal port of the integrated circuit.