A circuit breaker with thermal overload alarm and non-tripping function

Abstract

The present invention relates to a circuit breaker with a thermal overload alarm and non-tripping function, and relates to the field of low-voltage power distribution equipment. The circuit breaker includes a thermistor RP1, an operational amplifier U1A, an operational amplifier U1B, an operational amplifier U2A, an operational amplifier U2B, a voltage divider circuit, a resistor R7, a resistor R3, a diode D2, a diode D3, and a resistor R8. The circuit part of the present invention uses a thermistor to monitor the temperature of the heating element in real time, and can promptly feedback whether the main circuit current is overloaded. According to the heating characteristics of different circuit breaker products, the overload point can be flexibly adjusted to adapt to different application scenarios and load requirements. The design combining circuits and mechanical mechanisms improves the accuracy of the alarm and reduces the possibility of false alarms.

Description

Technical Field

[0001] The invention relates to the field of low-voltage power distribution equipment, and in particular to a circuit breaker with a thermal overload alarm and non-tripping function. Background Art

[0002] The "Low Voltage Power Distribution Design Code" GB50054-2011 clearly stipulates that for those lines where overload power outages will lead to serious consequences, the design principle of overload protection should not directly cut off the power line, but should alert maintenance personnel by sending signals. Such design requirements are mainly applicable to critical loads such as fire pumps and rotating motor excitation circuits. Even if this means that the service life of the conductor may be shortened, the continuity of power supply must be ensured.

[0003] However, existing solutions have some obvious shortcomings. The mainstream technical solutions on the market include: Solution 1: Use a single magnetic release in combination with a thermal overload relay. Although this solution can achieve overload protection, the complexity of its electrical wiring not only increases the workload of installation and maintenance, but also increases the overall cost. In addition, complex wiring may also lead to more failure points, thus affecting the stability and reliability of the system.

[0004] Solution 2: Use an electronic trip unit and turn off its overload protection function. Although this solution is more advanced in technology and can provide more precise control, its high cost limits its application in a wider range of scenarios. Especially in projects with limited budgets, this solution may not be the most economical choice. Summary of the invention

[0005] The purpose of the present invention is to provide a circuit breaker with a thermal overload alarm without tripping function, aiming to achieve the function of issuing an alarm without triggering the circuit breaker to trip under an overload condition.

[0006] In order to achieve the above-mentioned purpose, the technical solution of the present invention provides a circuit breaker with a thermal overload alarm non-tripping function, including a thermistor RP1, an operational amplifier U1A, an operational amplifier U1B, an operational amplifier U2A, and an operational amplifier U2B. The non-inverting input terminal of the operational amplifier U1A is electrically connected to a voltage divider circuit, and the inverting input terminal and the output terminal of the operational amplifier U1A are both electrically connected to the non-inverting input terminal of the operational amplifier U1B through a resistor. The non-inverting input terminal of the operational amplifier U1B is also grounded through a resistor R7, and the inverting input terminal of the operational amplifier U1B is grounded through a resistor R5 and the thermistor RP1 in turn; the thermistor RP1 is connected to One end of the resistor R5 is also connected to the working voltage VCC through the resistor R3. The output end of the operational amplifier U1B is electrically connected to the non-inverting input end of the operational amplifier U2A through the diode D2, wherein the output end of the operational amplifier U2A is connected to the cathode of the diode D3, and the output end of the operational amplifier U1B is also electrically connected to the non-inverting input end through the resistor R8; the inverting input end of the operational amplifier U2A is electrically connected to another reference voltage circuit, and the output end of the operational amplifier U2A is electrically connected to the alarm unit through the diode D3, wherein the operational amplifier U2A is electrically connected to the cathode of the diode D3, and the anode of the diode D3 is electrically connected to the non-inverting input end of the operational amplifier U2B.

[0007] Preferably, the alarm unit includes a relay K1 and a transistor Q1, the base of the transistor Q1 is electrically connected to the output end of the operational amplifier U2B through a resistor R12, the emitter of the transistor Q1 is grounded, the collector of the transistor Q1 is electrically connected to one end of the relay K1 coil, the other end of the relay K1 coil is electrically connected to the working voltage VDD, and the normally open contact of the relay K1 is electrically connected to the terminal block J1.

[0008] Preferably, the coil of the relay K1 is connected in parallel with a diode D4, wherein the anode of the diode D4 is electrically connected to the collector of the transistor Q1, and the cathode of the diode D4 is electrically connected to the operating voltage VDD.

[0009] Preferably, the non-inverting input terminal of the operational amplifier U2B is also connected to the ground through the capacitor C3 and to the working voltage VCC through the resistor R11.

[0010] Preferably, the thermistor RP1 is a negative temperature coefficient thermistor.

[0011] Preferably, the non-inverting input terminal of the operational amplifier U1A is connected to the operating voltage VCC and the rotary switch SW1 and the corresponding resistor to ground respectively through the resistor R1.

[0012] Preferably, the normally open contact of relay K1 is connected to terminal block J1.

[0013] Preferably, the resistor R9 is an adjustable potentiometer.

[0014] In summary, the present invention includes the following beneficial technical effects: It can effectively deal with lines where overload power outages will cause serious consequences, such as fire pumps, excitation circuits of rotating motors, power supply circuits of lifting electromagnets, etc. When overloaded, the line will not be cut off, but only the signal will be acted on to ensure uninterrupted power supply to important loads. The non-tripping function of the thermal overload alarm is achieved in three different ways, including designing a micro switch with a spring on the traction rod, designing a built-in thermal overload alarm contact accessory, and installing a thermostat thermal switch with a thermal overload alarm contact, providing a variety of options for different application scenarios.

[0015] The circuit uses a thermistor to monitor the temperature of the heating element in real time, and can provide timely feedback on whether the main circuit current is overloaded. According to the heating characteristics of different circuit breaker products, the overload point can be flexibly adjusted to adapt to different application scenarios and load requirements. The design of combining circuits and mechanical mechanisms improves the accuracy of the alarm and reduces the possibility of false alarms. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] Figure 1 This is a circuit diagram of a circuit breaker embodiment 1 with a thermal overload alarm non-tripping function according to the present invention; Figure 2 This is a schematic diagram of the mechanical structure of a circuit breaker with a thermal overload alarm and non-tripping function in Embodiment 2 of the present invention; Figure 3 It is a schematic diagram of the mechanical structure of a circuit breaker with a thermal overload alarm and non-tripping function in Embodiment 2 of the present invention; Figure 4 This is a schematic diagram of the mechanical structure of a circuit breaker with a thermal overload alarm and non-tripping function in Embodiment 3 of the present invention; Figure 5 It is a schematic diagram of the mechanical structure of a circuit breaker with a thermal overload alarm and non-tripping function in Embodiment 3 of the present invention; Figure 6 This is a schematic diagram of the mechanical structure of a circuit breaker with a thermal overload alarm and non-tripping function in Embodiment 4 of the present invention; Figure 7 It is a schematic diagram of the mechanical structure of a circuit breaker with a thermal overload alarm and non-tripping function in Embodiment 4 of the present invention; Figure 8 This is a schematic diagram of the mechanical structure of a circuit breaker with a thermal overload alarm and non-tripping function in Embodiment 5 of the present invention; Fig. 9 This is a schematic diagram of the mechanical structure of a circuit breaker with a thermal overload alarm and non-tripping function in Example 5 of the present invention. DETAILED DESCRIPTION

[0017] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0018] Embodiment 1:

[0019] This scheme describes in detail an overload alarm circuit for a circuit breaker. The circuit is ingeniously designed and can sound an alarm when the circuit breaker is overloaded, but will not trigger the circuit breaker's tripping mechanism. The circuit design includes multiple key components, including resistor R3, negative temperature coefficient thermistor RP1, resistor R5, resistor R8, operational amplifier U1B, operational amplifier U2A, diode D3, operational amplifier U2B, resistor R12, NPN transistor Q1, diode D4, relay K1, etc.

[0020] In this solution, the thermistor RP1 is a negative temperature coefficient thermistor, which means that its resistance value will change as the temperature rises. One end of the resistor R3 is connected to the positive voltage VCC, and the other end is connected to one end of the resistor R5 and one end of the thermistor RP1, while the other end of RP1 is grounded. The other end of the resistor R5 is connected to the inverting input of the operational amplifier U1B and one end of the resistor R8. The output of the operational amplifier U1B is connected to the other end of the resistor R8, and is connected to the non-inverting input of the operational amplifier U2A through the forward-set diode D2 or directly. The non-inverting input of the operational amplifier U1B is connected to an adjustable reference voltage circuit.

[0021] The reference voltage circuit includes resistor R1, resistor R2, operational amplifier U1A, resistor R6, and rotary switch SW1. One end of resistor R1 is connected to the positive voltage VCC, and the other end is connected to one end of rotary switch SW1 and the non-inverting input end of operational amplifier U1A, while the other terminals of rotary switch SW1 are connected to resistor R21, resistor R22, and resistor R23 respectively and then grounded. The inverting input end of operational amplifier U1A is connected to the output end of operational amplifier U1A and one end of resistor R6, and the other end of resistor R6 is connected to one end of resistor R7, so as to obtain another reference voltage, which is connected to the non-inverting input end of operational amplifier U1B. The other end of resistor R7 is grounded. Among them, resistor R1 is for sampling the rated current value, resistors R21, R22, and R23 are for matching resistor R1 to divide different rated current multiples, and rotary switch SW1 is for selecting overload current, and there is a corresponding rotary button; so as to meet the needs of different working conditions.

[0022] The inverting input of the operational amplifier U2A is connected to another reference voltage, while the output of the operational amplifier U2A is connected to the cathode of the diode D3, and the anode of the diode D3 is connected to the non-inverting input of the operational amplifier U2B. The reference voltage circuit connected to the inverting input of the operational amplifier U2A includes resistors R9 and R10. One end of the resistor R10 is connected to the positive voltage VCC, and the other end is connected to one end of the resistor R9, so as to obtain a reference voltage. The other end of the resistor R9 is grounded. The resistor R9 can use an adjustable potentiometer to obtain different comparison reference voltages, which makes the circuit applicable to circuit breaker products of different specifications.

[0023] The inverting input of the operational amplifier U2B is also connected to the reference voltage circuit, and the output of the operational amplifier U2B is connected to the base of the transistor Q1 through the resistor R12. The emitter of the transistor Q1 is grounded, and the collector of the transistor Q1 is connected to one end of the coil of the relay K1 and the anode of the diode D4, and the other end of the coil of the relay K1 and the cathode of the diode D4 are connected to the positive voltage VDD. The normally open contact of the relay K1 is connected to the terminal block J1. The positive voltages VCC and VDD can be generated by the power supply circuit, which is a conventional design in this field, so it will not be introduced in detail here.

[0024] In order to improve the stability of the circuit and reduce malfunction, this solution also adds a delay circuit, which includes a resistor R11 and a capacitor C3. One end of the resistor R11 is connected to the positive voltage VCC, and the other end is connected to one end of the capacitor C3 and the non-inverting input end of the operational amplifier U2B, and the other end of the capacitor C3 is grounded.

[0025] In this solution, the control of the circuit breaker is achieved by fixing the thermistor RP1 on the heating element of the circuit breaker. The resistance value of the thermistor RP1 will change in real time with the change of temperature. The resistor R1 and the resistance of the corresponding terminal of the rotary switch SW1 divide the positive voltage VCC, and the divided voltage value is input to the voltage follower composed of the operational amplifier U1A. When the circuit breaker is not overloaded, the resistance value of the thermistor RP1 is large, and the voltage on it is large, causing the operational amplifier U1B to output a low voltage, and the operational amplifier U2A also outputs a low voltage. Therefore, the diode D3 is turned on, and the voltage at the in-phase input terminal of the operational amplifier U2B is pulled down. The operational amplifier U2B also outputs a low voltage, the transistor Q1 will not be turned on, the relay K1 will not be attracted, and the terminal block J1 will not output an alarm signal.

[0026] However, when the circuit breaker heats up due to overload, the resistance of thermistor RP1 decreases and the voltage on it decreases. When the temperature of the circuit breaker exceeds the set reference temperature, the operational amplifier U1B will reverse and output a high level, causing the operational amplifier U2A to also output a high level, the diode D3 is cut off, and the in-phase input terminal of the operational amplifier U2B becomes a high level, which is greater than the corresponding reference voltage. Therefore, U2B outputs a high level, the transistor Q1 is turned on, the relay K1 is energized and closed, and the terminal block J1 outputs an alarm signal.

[0027] In order to solve the problem of fluctuation interference between the error amplification voltage and the critical value of the comparison reference voltage, a delay circuit is added to the circuit, which effectively avoids such problems, and the delay time can be adjusted by changing the device parameters.

[0028] The circuit design provided by this scheme is not only applicable to circuit breakers of various specifications, but also because the rated currents of the circuit breakers are different, the temperatures during overload are slightly different. By adjusting the adjustable potentiometer R9, different comparison reference voltages can be obtained, so that the circuit can be applied to products of various specifications.

[0029] In addition, the circuit design provided by this solution does not need to set the diode D2 when it is applied to single-channel temperature acquisition and monitoring; the first reference voltage circuit can use a simple two-resistance voltage divider circuit. At the same time, the circuit provided by this solution can also be applied to multi-channel temperature acquisition and monitoring. In this case, the diode D2 is needed, and then Figure 1 The circuit on the left side of the middle diode D2 can be simply repeated multiple times. Once the temperature of a circuit of the circuit breaker reaches the overload temperature first, the product can send out an overload alarm signal.

[0030] Finally, the mechanical structure of the circuit breaker is designed to trip when short-circuited and not trip when overloaded. Since the focus of this embodiment is to introduce the circuit design, the mechanical structure design of the circuit breaker is not introduced in detail.

[0031] Embodiment 2:

[0032] This embodiment is further improved on the basis of Embodiment 1, and the differences are as follows.

[0033] This embodiment also integrates the micro switch on the traction rod of the circuit breaker. When the circuit is overloaded, the thermal bimetallic strip will bend due to the thermal effect of the current, and this bending will push the micro switch, thereby triggering the output of the alarm signal. In order to ensure the smoothness of this process and reduce the impact on the main structure of the circuit breaker, an appropriate spring is added behind the micro switch in the design to buffer the force generated when the thermal bimetallic strip bends. Due to the action of the spring, the bending force of the thermal bimetallic strip is not enough to move the traction rod to a position sufficient to trip the circuit breaker, thereby realizing the function of only alarming but not tripping in the mechanical structure of the circuit breaker.

[0034] The use of an external thermal overload alarm module to implement solution 1 has significant flexibility. This module can be adjusted and optimized according to actual circuit requirements and installation environment. The design of the external module makes maintenance and replacement easier. At the same time, it will not affect the main structure of the circuit breaker, ensuring the stability and reliability of the circuit breaker.

[0035] In addition, the design of the plug-in module also allows users to choose the most suitable installation location and method according to specific application scenarios, further enhancing the adaptability and flexibility of the circuit breaker. This design not only improves the safety of the circuit breaker, but also provides users with more convenience and choices.

[0036] Through the innovative design combining circuit and mechanical structure of this embodiment, the present invention provides a brand new solution for thermal overload protection of circuit breakers.

[0037] Embodiment 3:

[0038] This embodiment is further improved on the basis of Embodiment 1, and the differences are as follows.

[0039] In the mechanical structure of this embodiment, the traditional traction rod is eliminated, and instead, a built-in thermal overload alarm contact accessory is designed inside the circuit breaker. The main function of this accessory is to cooperate with the thermal bimetal strip to receive the bending signal generated by the thermal bimetal strip due to overload. When the circuit is overloaded, the thermal bimetal strip will bend due to the principle of thermal expansion and contraction. This action will be captured by the built-in alarm contact accessory and converted into an alarm signal. It is worth noting that each alarm contact can only provide an overload alarm function for a single-phase circuit. Therefore, if it is necessary to provide an alarm function for a multi-phase circuit, a corresponding number of alarm contacts must be installed to ensure that each phase can sound an alarm when overloaded.

[0040] This built-in design makes the overall structure of the circuit breaker more compact, however, the space requirements of the built-in accessories need to be taken into account during the design, and the space of other accessories in the traditional circuit breaker may need to be borrowed. This is crucial because it ensures the accurate fit between the thermal bimetallic strip and the alarm contact, thereby ensuring the reliability of the alarm function.

[0041] During the implementation process, it is ensured that the built-in accessories will not interfere with the normal operation of the circuit breaker, and it is also ensured that the alarm mechanism can be accurately triggered in the case of overload. This design not only improves the safety of the circuit breaker, but also simplifies installation and maintenance by reducing the need for external accessories. In addition, the built-in design also helps to improve the neatness and aesthetics of the circuit breaker, because all the alarm mechanisms are cleverly hidden inside the circuit breaker. Through this innovative built-in thermal overload alarm contact accessory, combined with the basis of the circuit design in Example 1, the present invention provides new guarantees for the safety and reliability of the circuit breaker.

[0042] Embodiment 4:

[0043] This embodiment is further improved on the basis of Embodiment 1, and the differences are as follows.

[0044] In the mechanical structure of this embodiment, the circuit breaker no longer uses traditional thermal bimetal and traction rod, but a thermostat thermal switch is installed on the thermal element or conductor of the ABC three-phase. These thermostat thermal switches are used in conjunction with the designed thermal overload alarm contacts to detect the signal of the thermostat thermal switch. The thermostat temperature switch controls the on-off state of the circuit according to the temperature change of the controlled object. This embodiment preferably uses a KSD thermostat, which has a simple structure and low cost. The bimetallic strip composed of an upper layer of high manganese alloy and a lower layer of invar is used as a thermal sensitive reaction component. At normal temperature, the contact points of the copper sheet and the spring sheet are connected, and the circuit is in the on state. When the temperature rises, the expansion degree of the active layer (high manganese alloy) is greater than that of the passive layer (invar), causing the bimetallic strip to bend downward. When the temperature rises to a certain level, the circuit is disconnected; and when the temperature drops to a certain level, the bimetallic strip returns to its original state and the circuit is reconnected. The thermal overload alarm contact designed in this embodiment can detect the relevant signal of the thermostat and output an alarm signal, realizing the thermal overload alarm of the circuit breaker without tripping. In addition, the normally open and normally closed signals of the thermostat can also be output directly.

[0045] The use of thermostat thermal switch to realize thermal overload alarm has high accuracy and stability. Removing the existing thermal bimetal and installing a thermostat thermal switch is a relatively new method, which requires reasonable adjustment and optimization of the internal structure of the circuit breaker to ensure the normal operation of the thermostat and the effective coordination with the thermal overload alarm contact. Choosing KSD thermostat can reduce costs and improve the cost performance of the product. It should be noted that the thermal overload alarm contact can be realized either as a built-in accessory or by hanging it on the side of the circuit breaker.

[0046] Through this innovative design, combined with the basis of the circuit design in Example 1, this embodiment improves the safety and reliability of the circuit breaker and improves the market competitiveness of the product.

[0047] Embodiment 5:

[0048] This embodiment is further improved on the basis of Embodiment 1, and the differences are as follows.

[0049] In the mechanical structure of this embodiment, the traditional thermal bimetal and traction rod inside the circuit breaker are eliminated, and temperature sensors such as thermocouples, thermistors or other mature temperature sensors are installed on the thermal elements or conductors of the three phases ABC. These sensors are responsible for monitoring the temperature of the phase line and converting it into an electrical signal. Subsequently, a thermal overload alarm accessory is designed to receive data from the temperature sensor and output an alarm signal when an overload is detected. This design allows the circuit breaker to sound an alarm when overloaded, but will not immediately disconnect the circuit, thereby avoiding unnecessary power outages.

[0050] By measuring the temperature with a temperature sensor, accurate monitoring of the thermal overload of the circuit breaker can be achieved, thereby improving the stability and reliability of the system. Canceling the traditional thermal bimetallic strip and adopting a modern temperature sensor is a novel design idea, which requires adjustment and optimization of the internal structure of the circuit breaker to ensure accurate acquisition and output of the sensor signal. The thermal overload alarm accessory can be installed on the circuit breaker in a built-in or external manner, providing flexible installation options. This design is not only suitable for molded case circuit breakers, but also for miniature circuit breakers, so that this embodiment can be applied to a variety of circuit breakers. Selecting lower-cost temperature control components such as KSD thermostats can reduce overall costs and improve the cost-effectiveness of products.

[0051] The following are some examples of application scenarios of the circuit breaker with thermal overload alarm without tripping function of the present invention: 1. Fire protection system In the fire pump room, the fire pump needs to continue to operate in emergency situations such as fires, and cannot be powered off due to short-term overload of the line. Traditional circuit breakers may trip when overloaded, causing the fire pump to stop working and delaying the firefighting opportunity. However, when using the circuit breaker of this patent, when the fire pump line is overloaded, the circuit breaker will only send an alarm signal to remind the staff to check and deal with it, but will not cut off the line, ensuring that the fire pump can continue to operate stably and provide reliable protection for fire fighting and rescue.

[0052] 2. Industrial Production 1. Excitation circuit of rotating motor: In some industrial production processes, the excitation circuit of rotating motor is crucial to the continuity of production. If the circuit breaker trips when overloaded, it may cause production interruption and cause huge economic losses. The circuit breaker of the present invention can send out an alarm signal when the excitation circuit is overloaded, allowing the staff to adjust the production parameters or perform equipment maintenance in time without interrupting the power supply of the excitation circuit, thus ensuring the smooth progress of production.

[0053] 2. Power supply circuit of lifting electromagnet: During lifting operation, the lifting electromagnet needs a stable power supply. If the circuit breaker trips due to overload, the lifting electromagnet may suddenly lose its magnetic force, causing the heavy object to fall and cause a safety accident. When using the circuit breaker of the present invention, even if the power supply circuit is overloaded, it will only alarm without cutting off the power supply, ensuring the safety of the lifting operation.

[0054] 3. Medical Facilities Important medical equipment in hospitals, such as life support systems in operating rooms, intensive care equipment, etc., have extremely high requirements for power supply continuity. Once these devices lose power, the life safety of patients may be endangered. The circuit breaker of the present invention can send out an alarm signal when the equipment line is overloaded, allowing the hospital's electrical maintenance personnel to handle it in time without interrupting the power supply of the equipment, thereby providing protection for the life safety of patients.

[0055] 4. Data Center Servers, storage devices, etc. in data centers have very high requirements for the stability of power supply. If the circuit breaker trips due to overload, it may cause serious consequences such as data loss and server downtime. When the circuit breaker of the present invention is used, an alarm signal is issued when there is an overload, so that the operation and maintenance personnel of the data center can take timely measures, such as adding temporary power supply, adjusting equipment load, etc., without cutting off the power supply line, to ensure the normal operation of the data center.

[0056] Finally, it should be noted that the above is only a preferred embodiment of the present invention and is not intended to limit the present invention. Although the present invention has been described in detail with reference to the aforementioned embodiments, it is still possible for those skilled in the art to modify the technical solutions described in the aforementioned embodiments or to make equivalent substitutions for some of the technical features therein. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present invention should be included in the protection scope of the present invention.

Claims

1. A circuit breaker with a thermal overload alarm without tripping function, characterized in that: The invention comprises a thermistor RP1, an operational amplifier U1A, an operational amplifier U1B, an operational amplifier U2A and an operational amplifier U2B. The non-inverting input terminal of the operational amplifier U1A is electrically connected to a voltage divider circuit. The inverting input terminal and the output terminal of the operational amplifier U1A are both electrically connected to the non-inverting input terminal of the operational amplifier U1B through a resistor. The non-inverting input terminal of the operational amplifier U1B is also grounded through a resistor R7. The inverting input terminal of the operational amplifier U1B is grounded through a resistor R5 and the thermistor RP1 in sequence. The thermistor RP1 is a negative temperature coefficient thermistor. One end of the thermistor RP1 connected to the resistor R5 is also connected to the resistor R7 through a resistor R8. The resistor R3 is connected to the working voltage VCC, and the output end of the operational amplifier U1B is electrically connected to the non-inverting input end of the operational amplifier U2A through the diode D2, wherein the output end of the operational amplifier U2A is connected to the cathode of the diode D3, and the output end of the operational amplifier U1B is electrically connected to the non-inverting input end through the resistor R8; the inverting input end of the operational amplifier U2A is electrically connected to another reference voltage circuit, and the output end of the operational amplifier U2A is electrically connected to the alarm unit through the diode D3, wherein the operational amplifier U2A is electrically connected to the cathode of the diode D3, and the anode of the diode D3 is electrically connected to the non-inverting input end of the operational amplifier U2B.

2. A circuit breaker with a thermal overload alarm without tripping function according to claim 1, characterized in that: The alarm unit includes a relay K1 and a transistor Q1. The base of the transistor Q1 is electrically connected to the output end of the operational amplifier U2B through a resistor R12. The emitter of the transistor Q1 is grounded. The collector of the transistor Q1 is electrically connected to one end of the relay K1 coil. The other end of the relay K1 coil is electrically connected to the working voltage VDD. The normally open contact of the relay K1 is electrically connected to the terminal block J1.

3. A circuit breaker with a thermal overload alarm without tripping function according to claim 2, characterized in that: The coil of relay K1 is connected in parallel with a diode D4, wherein the anode of diode D4 is electrically connected to the collector of transistor Q1, and the cathode of diode D4 is electrically connected to a working voltage VDD; the normally open contact of relay K1 is connected to terminal block J1.

4. A circuit breaker with a thermal overload alarm without tripping function according to claim 1, characterized in that: The non-inverting input terminal of the operational amplifier U2B is also connected to the ground through the capacitor C3 and to the operating voltage VCC through the resistor R11.

5. A circuit breaker with a thermal overload alarm without tripping function according to claim 1, characterized in that: The non-inverting input terminal of the operational amplifier U1A is connected to the operating voltage VCC and the rotary switch SW1 and the corresponding resistor to ground through the resistor R1.

6. A circuit breaker with a thermal overload alarm without tripping function according to claim 1, characterized in that: Resistor R9 adopts adjustable potentiometer.

7. A circuit breaker with a thermal overload alarm without tripping function according to claim 1, characterized in that: The utility model comprises a traction rod, on which a micro switch is integrated. When the micro switch is pushed, the micro switch is triggered to output an alarm signal.

8. A circuit breaker with a thermal overload alarm without tripping function according to claim 1, characterized in that: Includes built-in thermal overload alarm contact accessory, which can capture the bending action of the thermal bimetallic strip and convert it into an alarm signal.

9. A circuit breaker with a thermal overload alarm without tripping function according to claim 1, characterized in that: It includes a thermostat thermal switch arranged on an ABC three-phase thermal element or conductor and a thermal overload alarm contact used in conjunction with the thermostat thermal switch to detect the signal of the thermostat thermal switch.

10. A circuit breaker with a thermal overload alarm without tripping function according to claim 1, characterized in that: It includes temperature sensors arranged on the thermal elements or conductors of the three phases ABC, and a thermal overload alarm accessory. The temperature sensor monitors the phase line temperature and converts it into an electrical signal and sends it to the thermal overload alarm accessory. The thermal overload alarm accessory outputs an alarm signal when an overload condition is detected.

Images