Temperature control circuit for control box

Abstract

The utility model relates to the technical field of electrical control, in particular to a temperature control circuit for a control box, which comprises a starting circuit, an auxiliary circuit and a temperature control circuit. The start circuit comprises a stop button, a start button, a contactor coil and a thermal relay auxiliary switch; the stop button, the start button and the contactor coil are sequentially connected in series between a power supply L11 end and a power supply L13 end; one end of the auxiliary circuit is connected between the stop button and the start button, the other end is connected with the L13 end of the power supply, and the auxiliary circuit is connected with a contactor auxiliary switch; the temperature control circuit comprises a temperature controller coil and a temperature controller auxiliary switch, the temperature controller coil is connected between the power supply L11 end and the power supply L13 end, one end of the temperature controller auxiliary switch is connected with the power supply L11 end, and the other end of the temperature controller auxiliary switch is connected between the start button and the contactor coil. The temperature controller auxiliary switch accurately controls the on-off of the contactor coil according to the temperature change.

Description

Technical Field

[0001] This utility model relates to the field of electrical control technology, and in particular to a temperature control circuit for a control box. Background Technology

[0002] In numerous industrial production, scientific research experiments, and everyday heating or cooling equipment, precise temperature control is a key factor in ensuring product quality, improving production efficiency, ensuring safe equipment operation, and meeting specific process requirements. For example, in the plastics processing industry, precise temperature control is crucial for the molding quality of plastics; in food processing, different processing stages require strict temperature control to ensure food safety and taste; and in the manufacturing of electronic devices, chip packaging and soldering also have extremely high temperature requirements.

[0003] However, traditional temperature control circuits have many shortcomings. Many temperature control circuits have relatively simple functions and can only achieve simple temperature control, which cannot meet the complex and ever-changing actual needs. For example, the temperature control circuits of some small heating equipment can only maintain a basic constant temperature state and cannot be flexibly adjusted according to different working stages or environmental conditions.

[0004] In summary, in order to meet the high requirements of modern industry and daily life for temperature control circuits, there is an urgent need for a temperature control circuit with complete functions, flexible control, reliable overload protection, and clear status indication. Utility Model Content

[0005] In view of the shortcomings in the above-mentioned background technology, this utility model proposes a temperature control circuit for a control box, which solves the technical problem that traditional temperature control circuits have many shortcomings. Many temperature control circuits have relatively simple functions and can only achieve simple temperature control, which cannot meet the complex and ever-changing actual needs.

[0006] The technical solution of this utility model is implemented as follows: A temperature control circuit for a control box includes a power supply L11 terminal and a power supply L13 terminal, characterized in that it further includes a start-up circuit, an auxiliary circuit, and a temperature control circuit; the start-up circuit includes a stop button, a start button, a contactor coil, and a thermal relay auxiliary switch, wherein the stop button, start button, and contactor coil are connected in series between the power supply L11 terminal and the power supply L13 terminal; one end of the auxiliary circuit is connected between the stop button and the start button, and the other end is connected to the power supply L13 terminal, and a contactor auxiliary switch is connected to the auxiliary circuit; the temperature control circuit includes a temperature controller coil and a temperature controller auxiliary switch, wherein the temperature controller coil is connected between the power supply L11 terminal and the power supply L13 terminal, and one end of the temperature controller auxiliary switch is connected to the power supply L11 terminal, and the other end is connected between the start button and the contactor coil.

[0007] As a preferred embodiment, an overload protection circuit is also included, which includes a thermal relay auxiliary switch and a thermal relay main circuit. One end of the thermal relay auxiliary switch is connected to the contactor coil, and the other end is connected to the power supply L13 terminal. The thermal relay main circuit is connected in series in the main circuit of the equipment.

[0008] As a preferred embodiment, the auxiliary circuit also includes a power indicator light, one end of which is connected to the contactor auxiliary switch and the other end is connected to the power supply L13 terminal.

[0009] As a preferred embodiment, the starting circuit includes a changeover switch, which includes two sets of first contact terminals and two sets of second contact terminals. One end of each of the two sets of first contact terminals is connected to the stop button, and the other end is connected to the L11 terminal. One end of each of the two sets of second contact terminals is connected to the temperature controller auxiliary switch, and the other end is connected to the L11 terminal.

[0010] As a preferred embodiment, a running indicator light is also included, which is connected between power supply L11 and power supply L13.

[0011] As a preferred embodiment, the system also includes a thermal relay auxiliary switch and a thermal relay main circuit. One end of the thermal relay auxiliary switch is connected to the contactor coil, and the other end is connected to the power supply L13 terminal. The thermal relay main circuit is connected in series in the main circuit of the equipment.

[0012] As a preferred embodiment, the circuit wiring inside the control box is carried out using cable trays or cable ducts.

[0013] The beneficial effects of this utility model are:

[0014] I. This temperature control circuit, through its meticulously designed circuitry, achieves precise temperature regulation of the equipment. The temperature controller coil is continuously energized, ensuring real-time monitoring of the ambient temperature. The auxiliary switch of the temperature controller precisely controls the on / off state of the contactor coil based on temperature changes, thereby adjusting the operating status of the heating or cooling equipment. This closed-loop control method ensures that the equipment temperature remains stable near the set value, effectively avoiding the adverse effects of excessive temperature fluctuations on product quality and the production process. For example, in chemical reactions, precise temperature control ensures that the chemical reaction proceeds under optimal conditions, improving reaction conversion rate and product purity. In precision machining, a stable temperature environment helps ensure the machining accuracy of parts and reduces dimensional deviations caused by thermal expansion and contraction.

[0015] II. The unique design of the selector switch adds flexibility to the temperature control circuit. Through the ingenious connection of its two sets of first contacts and two sets of second contacts, convenient switching between manual and automatic control modes is achieved. In manual control mode, operators can directly and precisely start and stop the equipment using the start and stop buttons, suitable for equipment debugging, maintenance, or situations requiring manual intervention under special process requirements. In automatic control mode, the selector switch works in conjunction with the temperature controller's auxiliary switch, automatically controlling the equipment's operation according to the temperature parameters set by the temperature controller. This achieves automated and intelligent temperature control, significantly improving production efficiency, reducing human error, and making it suitable for continuous and stable operation in large-scale production processes.

[0016] Other advantages, objectives and features of this invention will be set forth in part in the description which follows, and in part will be apparent to those skilled in the art from the following examination or study, or may be taught from the practice of this invention. Attached Figure Description

[0017] To more clearly illustrate the embodiments of this utility model, the drawings used in the description of the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of this utility model. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0018] Figure 1 This is a schematic diagram of the electrical principle of this utility model.

[0019] In the diagram: 1: Power supply L11 terminal, 2: Power supply L13 terminal, 3: Stop button, 4: Start button, 5: Contactor coil, 6: Contactor auxiliary switch, 7: Temperature controller coil, 8: Temperature controller auxiliary switch, 9: Thermal relay auxiliary switch, 10: Power indicator light, 11: Changeover switch, 12: Run indicator light. Detailed Implementation

[0020] The following will refer to the appendix in the embodiments of this utility model. Figure 1 The technical solutions in the embodiments of this utility model are clearly and completely described herein. Obviously, the described embodiments are only some embodiments of this utility model, and not all embodiments. Based on the embodiments of this utility model, all other embodiments obtained by those skilled in the art without creative effort are within the protection scope of this utility model.

[0021] Example 1: A temperature control circuit for a control box, comprising a power supply terminal L11 1 and a power supply terminal L13 2, characterized in that it further includes a start-up circuit, an auxiliary circuit, and a temperature control circuit; the start-up circuit includes a stop button 3, a start button 4, and a contactor coil 5, which are connected in series between power supply terminal L11 1 and power supply terminal L13 2; one end of the auxiliary circuit is connected between the stop button 3 and the start button 4, and the other end is connected to power supply terminal L13 2, and a contactor auxiliary switch 6 is connected to the auxiliary circuit; the temperature control circuit includes a temperature controller coil 7 and a temperature controller auxiliary switch 8, the temperature controller coil 7 being connected between power supply terminal L11 1 and power supply terminal L13 2, and one end of the temperature controller auxiliary switch 8 being connected to power supply terminal L11 1, and the other end being connected between the start button 4 and the contactor coil 5.

[0022] As a further embodiment, an overload protection circuit is also included, which includes a thermal relay auxiliary switch 9 and a thermal relay main circuit. One end of the thermal relay auxiliary switch 9 is connected to the contactor coil 5, and the other end is connected to the power supply L13 terminal. The thermal relay main circuit is connected in series in the main circuit of the equipment.

[0023] As a further embodiment, the auxiliary circuit also includes a power indicator light 10, one end of which is connected to the contactor auxiliary switch 6, and the other end is connected to the power supply L13 terminal.

[0024] As a further embodiment, the start-up circuit includes a changeover switch 11, which includes two sets of first contact terminals and two sets of second contact terminals. One end of the two sets of first contact terminals is connected to the stop button 3, and the other end is connected to the L11 terminal. One end of the two sets of second contact terminals is connected to the temperature controller auxiliary switch 8, and the other end is connected to the L11 terminal.

[0025] As a further embodiment, a running indicator light 12 is also included, which is connected between the power supply L11 terminal and the power supply L13 terminal.

[0026] As a further embodiment, it also includes a thermal relay auxiliary switch 9 and a thermal relay main circuit. One end of the thermal relay auxiliary switch 9 is connected to the contactor coil 5, and the other end is connected to the power supply L13 terminal. The thermal relay main circuit is connected in series in the main circuit of the equipment.

[0027] As a further embodiment, the temperature control circuit is installed inside the control box, and the circuit wiring inside the control box is carried out using cable trays or cable management systems.

[0028] I. Working Principle

[0029] Start-up and Stop Principle: When the equipment is in its initial state, the stop button 3 is normally closed and the start button 4 is normally open. After pressing the start button 4, current flows from power supply L11 terminal 1, through the stop button 3 (currently conducting), the start button 4 (conducting after being pressed), and the contactor coil 5, finally flowing back to power supply L13 terminal 2, forming a circuit. The contactor coil 5 is energized, generating a magnetic field that closes the contactor main contacts, thus connecting the main circuit of the equipment and starting operation. Simultaneously, the contactor auxiliary switch 6 in the auxiliary circuit closes as the contactor coil 5 is energized, achieving a self-holding function. Even if the start button 4 is released, current can still pass through the contactor auxiliary switch 6, keeping the contactor coil 5 continuously energized and the equipment continuously running. When it is necessary to stop the equipment, pressing the stop button 3 opens the current circuit of the contactor coil 5, de-energizing it, opening the contactor main contacts, cutting off the main circuit of the equipment, and stopping operation.

[0030] Temperature control principle: The temperature controller coil 7 is always connected between power supply L11 terminal 1 and power supply L13 terminal 2, and is in a energized state, enabling it to monitor the ambient temperature in real time. The temperature controller internally judges according to the preset temperature parameters. When the ambient temperature is detected to be lower than the set lower limit temperature, the temperature controller auxiliary switch 8 closes. At this time, the current flows from power supply L11 terminal 1, through the temperature controller auxiliary switch 8 and contactor coil 5 back to power supply L13 terminal 2, energizing the contactor coil 5 (if the equipment has stopped at this time, it will be restarted). The equipment starts heating or running to raise the temperature. When the ambient temperature rises to the set upper limit temperature, the temperature controller auxiliary switch 8 opens, the contactor coil 5 is de-energized, the equipment stops heating or running, and the temperature begins to drop. This cycle continues. By controlling the opening and closing of the temperature controller auxiliary switch 8, the temperature of the equipment is precisely controlled and kept stable within the set temperature range.

[0031] Overload protection principle: The thermal relay main circuit is connected in series in the main circuit of the equipment to monitor the current in the main circuit in real time. When the equipment is running normally, the current in the main circuit is within the normal range, and the thermal relay main circuit remains in normal state. When the equipment is overloaded and the current in the main circuit exceeds the overload protection current value preset by the thermal relay, the thermal relay main circuit will act quickly. The thermal relay auxiliary switch 9 is linked with the thermal relay main circuit. When the thermal relay main circuit acts, the thermal relay auxiliary switch 9 will open. One end of the thermal relay auxiliary switch 9 is connected to the contactor coil 5, and the other end is connected to the power supply L13 terminal 2. After it is opened, it cuts off the current circuit of the contactor coil 5, causing the contactor coil 5 to lose power, which in turn causes the contactor main contacts to open and the main circuit of the equipment to be de-energized. This achieves overload protection for the equipment and prevents the equipment from being damaged due to prolonged overload.

[0032] Control Mode Switching Principle (Changeover Switch): Changeover switch 11 has manual and automatic control modes. Switching between modes is achieved through different connection methods of two sets of first contacts and two sets of second contacts. In manual control mode, both sets of first contacts of changeover switch 11 are closed, and current flows from power supply L11 terminal 1, through stop button 3, start button 4, and contactor coil 5 back to power supply L13 terminal 2. At this time, the start and stop of the equipment are entirely controlled manually by the operator using start button 4 and stop button 3, regardless of the state of the temperature controller auxiliary switch 8. In automatic control mode, both sets of second contacts of changeover switch 11 are closed, and the temperature controller auxiliary switch 8 is connected to the control circuit. At this time, the start and stop of the equipment are controlled by the temperature controller based on temperature monitoring results, thus automating the equipment temperature control. Operators can flexibly switch control modes according to actual needs, such as using manual control mode during equipment debugging, maintenance, or special process requirements, and automatic control mode during normal production.

[0033] Status indication principle: One end of the power indicator light 10 is connected to the contactor auxiliary switch 6, and the other end is connected to the power supply L13 terminal 2. When the contactor auxiliary switch 6 is closed (i.e., the equipment is starting up or in the preparation state), the power indicator light 10 forms a circuit and lights up, indicating that the power supply has been normally connected to the circuit and the equipment is powered on. The operation indicator light 12 is connected between the power supply L11 terminal 1 and the power supply L13 terminal 2. When the equipment is running, the contactor coil 5 is energized, the circuit where the operation indicator light 12 is located is connected, and the operation indicator light 12 lights up, indicating that the equipment is running. By observing the on / off state of the power indicator light 10 and the operation indicator light 12, the operator can intuitively understand the power supply connection and operating status of the equipment, which is convenient for timely detection of equipment faults or abnormalities.

[0034] When using electrical components, select appropriate specifications based on the equipment's power, operating voltage, operating current, temperature control range and accuracy requirements.

[0035] For contactors, select the appropriate contactor model based on the rated current of the main circuit of the equipment, and ensure that the rated current of the contactor is greater than the operating current of the equipment during normal operation. For example, if the equipment power is 5kW and the operating voltage is 380V, a contactor with a rated current of 16A can be selected, such as the Chint CJX2-1810 series contactor. The contactor coil voltage should match the power supply voltage, such as selecting a contactor with a coil voltage of 220V or 380V.

[0036] The selection of a temperature controller should be based on the required temperature control range and accuracy. If the equipment needs to control the temperature between 0-100℃ with an accuracy requirement of ±1℃, the Omron E5CC series temperature controller can be selected, as its temperature measurement range and control accuracy can meet the requirements.

[0037] The selection of thermal relays is determined based on the rated current and overload protection factor of the equipment. For example, if the rated current of the equipment is 10A and the overload protection factor is set to 1.2 times, then the Chint JR36-20 series thermal relay can be selected, and its operating current range can cover the overload protection requirements of the equipment.

[0038] The indicator lights are ordinary LED indicator lights, such as the power indicator light 10 and the running indicator light 12. They can be red or green LED indicator lights with a working voltage of 220V or 380V, which have the advantages of high brightness, long life and low energy consumption.

[0039] The selector switch 11 can be selected according to the control requirements, such as the Delixi LW5D-16 series universal selector switch, which has the characteristics of convenient operation and clear position.

[0040] For the push-button switches (stop button 3 and start button 4), select normally open and normally closed buttons with good feel and reliability, such as the LAY3 series push-button switches, to ensure that the buttons are flexible and durable.

[0041] Circuit connection and installation: Install the electrical component mounting plate inside the control box, and install components such as contactors, temperature controllers, thermal relays, and changeover switches on the mounting plate. Secure them with screws to ensure a firm installation. For heat-generating components (such as contactors and thermal relays), they should be installed in locations with good heat dissipation to avoid affecting component performance and lifespan due to overheating.

[0042] Wiring should be done according to the circuit schematic, using copper core wires of appropriate specifications. The cross-sectional area of ​​the wires should be selected according to the circuit current to ensure that the wires can withstand the normal operating current and have a certain margin. For example, 2.5mm² or 4mm² copper core wires can be used for the main circuit wires, and 1.5mm² or 2.5mm² copper core wires can be used for the control circuit wires.

[0043] When wiring, electrical wiring specifications should be followed. Power lines (L11 terminal 1 and L13 terminal 2), control lines, signal lines, etc. should be classified and wired separately to avoid crossing and tangling. The wires should be neatly laid along the cable trays or cable troughs. The cable trays or cable troughs should be fixed in a suitable position inside the control box to ensure that the wiring is aesthetically pleasing, secure and easy to maintain.

[0044] Connect the wires between the components, ensuring that the connection points are firm and reliable. For components with plug and socket connections, ensure that the plug and socket make good contact and avoid loose connections. When connecting the main circuit of the thermal relay and the main circuit of the equipment, pay attention to the connection sequence and polarity (if required) to ensure that the overload protection function is normal.

[0045] Install the power indicator light 10, the run indicator light 12, the stop button 3, and the start button 4 on the control box panel for easy operation and observation by the operator. The installation height of the buttons should be moderate to facilitate operation by the operator, and the installation position of the indicator lights should be obvious and easy to observe.

[0046] Debugging process: After the circuit connection is completed, a preliminary inspection is performed to ensure that all components are securely installed, wires are connected correctly, and there are no short circuits, open circuits, or other issues. Check that the wires in the cable trays or cable ducts are neat and that there are no loose or exposed wires.

[0047] Turn on the power and observe whether the power indicator light 10 lights up. If the power indicator light 10 does not light up, immediately turn off the power and check whether the power line connection is correct, including whether the power plug is plugged in properly, whether the power switch is working properly, and whether the power cord is broken.

[0048] After the power indicator light 10 lights up, switch the selector switch 11 to the manual control position, press the start button 4, and observe whether the contactor is engaged. You can judge by listening to the sound of the contactor engaging or by observing the status of the contactor's main contacts. If the contactor is not engaged, check the starting circuit connection, including whether the connection between the stop button 3, the start button 4, and the contactor coil 5 is loose or incorrect. At the same time, check whether the contactor coil is damaged.

[0049] After the contactor engages, the equipment should start running. Observe whether the running indicator light 12 is lit. If the running indicator light 12 is not lit, check whether the connection circuit of the running indicator light 12 is correct.

[0050] In manual control mode, test whether the device’s start and stop functions are normal. Press the start button 4 and stop button 3 multiple times and observe whether the device can accurately respond to the operation commands and start and stop normally.

[0051] After the manual control function is tested and found to be normal, switch the selector switch 11 to the automatic control position, and set the temperature parameters of the temperature controller according to the equipment requirements, including the upper limit temperature and the lower limit temperature.

[0052] Use a temperature measuring tool (such as a thermometer) to measure the ambient temperature and observe whether the temperature controller can accurately control the operation of the equipment according to temperature changes. When the ambient temperature is lower than the lower limit temperature, the auxiliary switch 8 of the temperature controller should be closed, and the equipment should start heating or running. When the ambient temperature reaches the upper limit temperature, the auxiliary switch 8 of the temperature controller should be opened, and the equipment should stop heating or running. Observe whether the equipment temperature can be stabilized within the set temperature range. If the temperature control is inaccurate, check whether the parameter settings of the temperature controller, the installation position of the temperature sensor, and the connection of the auxiliary switch 8 of the temperature controller are normal.

[0053] Perform overload protection function tests. During equipment operation, simulate overload conditions, such as increasing the equipment load so that the main circuit current exceeds the overload current value set by the thermal relay. Observe whether the thermal relay can act quickly, whether the thermal relay auxiliary switch 9 is disconnected, and whether the equipment stops running. If the thermal relay does not act or acts abnormally, check whether the overload current setting of the thermal relay is correct and whether the connection between the thermal relay main circuit and the auxiliary switch 9 is reliable.

[0054] Practical Application and Maintenance: In practical applications, the parameters of the temperature controller should be set reasonably according to the specific working process and process requirements of the equipment to ensure that the equipment operates under the optimal temperature conditions. The operating status of the equipment should be checked regularly, and the power indicator light 10 and the operation indicator light 12 should be observed to see if they are normal. The equipment should be judged to have any abnormalities by listening to the operating sound of the equipment and checking the temperature of the equipment.

[0055] Regularly maintain the electrical components inside the control box, such as cleaning dust from the surfaces of contactors and thermal relays, and checking for loose wiring terminals. For temperature controllers, calibrate temperature sensors regularly to ensure accurate temperature measurements. If any component is found to be damaged or its performance degraded, replace it with a component of the same specification promptly.

[0056] When restarting equipment after a prolonged shutdown, a comprehensive inspection should be performed first to ensure that the circuit connections are normal and the components are undamaged. Then, follow the startup procedures. During equipment operation, avoid frequently switching the positions of the selector switch 11 to prevent unnecessary stress on the equipment. If equipment malfunctions, first determine the scope of the fault based on the status of the power indicator light 10 and the running indicator light 12, as well as the equipment's behavior. Then, troubleshoot and repair the fault according to electrical maintenance safety regulations.

[0057] In this application, unless otherwise expressly specified and limited, the terms "installation," "connection," "joining," and "fixing," etc., should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral part; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; they can refer to the internal communication of two components or the interaction between two components. Those skilled in the art can understand the specific meaning of the above terms in this application according to the specific circumstances. In this application, unless otherwise expressly specified and limited, "above" or "below" the second feature can mean that the first and second features are in direct contact, or that the first and second features are in indirect contact through an intermediate medium. Furthermore, "above," "on top of," and "on top" can mean that the first feature is directly above or diagonally above the second feature, or simply that the first feature is at a higher horizontal level than the second feature. "Below," "under," and "below" can mean that the first feature is directly below or diagonally below the second feature, or simply that the first feature is at a lower horizontal level than the second feature. In the description of this specification, the references to terms such as "one embodiment," "some embodiments," "example," "specific example," or "some examples," etc., indicate that a specific feature, structure, material, or characteristic described in connection with that embodiment or example is included in at least one embodiment or example of this application. In this specification, the illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or examples. Moreover, without contradiction, those skilled in the art can combine and integrate the different embodiments or examples described in this specification, as well as the features of different embodiments or examples.

[0058] Although embodiments of this application have been shown and described above, it is understood that the above embodiments are exemplary and should not be construed as limiting this application. Those skilled in the art can make changes, modifications, substitutions and variations to the above embodiments within the scope of this application.

Claims

1. A temperature control circuit for a control box, comprising a power supply terminal L11 (1) and a power supply terminal L13 (2), characterized in that: It also includes a start circuit, an auxiliary circuit, and a temperature control circuit; the start circuit includes a stop button (3), a start button (4), and a contactor coil (5), the stop button (3), the start button (4), and the contactor coil (5) are connected in series between the power supply L11 terminal (1) and the power supply L13 terminal (2); one end of the auxiliary circuit is connected between the stop button (3) and the start button (4), and the other end is connected to the power supply L13 terminal (2), and a contactor auxiliary switch (6) is connected on the auxiliary circuit; the temperature control circuit includes a temperature controller coil (7) and a temperature controller auxiliary switch (8), the temperature controller coil (7) is connected between the power supply L11 terminal (1) and the power supply L13 terminal (2), one end of the temperature controller auxiliary switch (8) is connected to the power supply L11 terminal (1), and the other end is connected between the start button (4) and the contactor coil (5).

2. The temperature control circuit for a control box according to claim 1, characterized in that, It also includes an overload protection circuit, which includes a thermal relay auxiliary switch (9) and a thermal relay main circuit. One end of the thermal relay auxiliary switch (9) is connected to the contactor coil (5), and the other end is connected to the power supply L13 terminal (2). The thermal relay main circuit is connected in series in the main circuit of the equipment.

3. The temperature control circuit for a control box according to claim 1, characterized in that, The auxiliary circuit also includes a power indicator light (10), one end of which is connected to the contactor auxiliary switch (6), and the other end is connected to the power supply L13 terminal (2).

4. A temperature control circuit for a control box according to claim 1, characterized in that, The starting circuit includes a changeover switch (11), which includes two sets of first contact terminals and two sets of second contact terminals. One end of the two sets of first contact terminals is connected to the stop button (3), and the other end is connected to the L11 terminal (1). One end of the two sets of second contact terminals is connected to the temperature controller auxiliary switch (8), and the other end is connected to the L11 terminal.

5. A temperature control circuit for a control box according to claim 1, characterized in that, It also includes a running indicator (12), which is connected between the power supply L11 terminal (1) and the power supply L13 terminal (2).

6. A temperature control circuit for a control box according to claim 1, characterized in that, It also includes a thermal relay auxiliary switch (9) and a thermal relay main circuit. One end of the thermal relay auxiliary switch (9) is connected to the contactor coil (5), and the other end is connected to the power supply L13 terminal (2). The thermal relay main circuit is connected in series in the main circuit of the equipment.

7. A temperature control circuit for a control box according to any one of claims 1-6, characterized in that, The temperature control circuit is located inside the control box, and the wiring inside the control box is done using cable trays or cable management systems.

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