Electric switch
By incorporating thermal protection devices for non-current overload heating and current overload in low-voltage switches, the tripping mechanism is directly driven to disconnect the circuit, thus solving the problem of switch damage due to abnormal heating in existing technologies, achieving early protection and cost reduction.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-01-13
- Publication Date
- 2026-04-10
AI Technical Summary
Existing low-voltage switches are prone to damage due to abnormal heating under non-current abnormal conditions, and existing smoke detection sensors are slow to respond and expensive, and cannot effectively prevent switches from catching fire.
In low-voltage switches, thermal protection devices for non-current overload and current overload are installed. The tripping mechanism is driven directly or indirectly by the thermal element to trip the switch, avoiding damage caused by abnormal heating. The control unit is eliminated, and the circuit is disconnected by mechanical transmission.
It achieves early protection under non-abnormal current conditions, avoids irreversible damage to the switch, is low in cost, responds quickly, and reduces the overall cost of the switch.
Smart Images
Figure CN121839489A_ABST
Abstract
Description
TECHNICAL FIELD
[0001] The present application relates to the field of switch, in particular to a switch with abnormal heating protection function. BACKGROUND
[0002] In the field of low-voltage switch, when the switch is protected, the current is generally detected, and when the current is abnormal, the locking mechanism of the operating mechanism is unlocked by the tripping mechanism of the switch, and the switch is turned off.
[0003] However, in the actual application field, abnormal heating caused by non-current abnormality often occurs, such as abnormal increase of contact resistance caused by untightened terminal screws, which leads to excessive temperature rise and burning of the switch. Abnormal heating will occur when the moving contact and the static contact are missing contacts or missing pressure springs, and even fire.
[0004] In the known technology of electrical switch fire prevention, a smoke detection sensor is used for non-abnormal heating protection, which has the following problems: 1. Since the raw materials generally used in electrical switches have high flame retardant level, the smoke detection sensor can only detect when the electrical switch starts to burn, and at this time the electrical switch has caused irreversible damage; 2. Using smoke detection sensor for switch protection, a control unit must be used to transmit the smoke detection sensor signal to the switch control unit, and the control unit sends a tripping signal to the drive device, which drives the moving contact device and the static contact device to electrically disconnect. Since the control unit is indispensable, it will inevitably lead to high cost; 3. The sensor signal must be processed by the control unit and then sent to the transmission device to turn off the electrical switch, which will inevitably lead to long response. Therefore, this way of fire protection has certain limitations. SUMMARY
[0005] Based on the above background, the present application provides an electrical switch with abnormal heating protection function, which can overcome the above problems.
[0006] The application provides an electric switch, at least one set of non-current overload heat protection device, one set of current overload heat protection device, front power connection device, rear power connection device, moving contact device, static contact device, tripping mechanism, operating mechanism, the operating mechanism directly or indirectly drives the moving contact device and the static contact device to carry out electric connection and disconnection; one set of the non-current overload heat protection device and one set of the current overload heat protection device are arranged in the front power connection device and the rear power connection device, or two sets of the non-current overload heat protection device are arranged in the front power connection device and the rear power connection device; the non-current overload heat protection device and the current overload heat protection device are both provided with a thermal element, and the thermal element directly or indirectly drives the tripping mechanism to act to trip the switch to disconnect the circuit.
[0007] Compared with the prior art, the non-current overload heat protection device is arranged in the electric switch, and can directly or indirectly drive the tripping mechanism to act to trip the switch to disconnect the circuit, the output is the bending action of the thermal element, the tripping mechanism can be directly or indirectly driven to act, a control unit is not necessarily used, the structure is simple, the cost is low, and the electric switch is easy to realize. Since the heat source of the non-current overload heat protection device is non-current heat, the installation position can be placed at a position where non-current overload heat, i.e. abnormal heat, can be generated, and is not affected by whether current flows. When the detection part is subjected to abnormal heat, the switch can be disconnected to protect against irreversible damage caused by abnormal heat.
[0008] In some embodiments, the tripping mechanism comprises a lock catch, and the operating mechanism comprises a trip catch, and the lock catch and the trip catch are overlapped.
[0009] In the above embodiment, the lock catch and the trip catch are overlapped between the tripping mechanism and the operating mechanism, so that a smaller force and position can be used to unlock the mechanism and trip the switch to disconnect the circuit.
[0010] In some embodiments, a conductor is arranged on one end or both ends of the thermal element of the current overload heat protection device.
[0011] In the above embodiment, since the heat source of the current overload heat protection device is the heat source generated by current heat, and the deformation of the thermal element has a specific relationship with the size of the current, the thermal element is arranged to pass through the current or part of the current, or is arranged on the conductor to conduct heat.
[0012] In some embodiments, no soft conductor is arranged on one end of the thermal element of the non-current overload heat protection device.
[0013] In the above embodiments, the heat source of the non-current overload thermal protection device is the heat source generated by non-current heating. After thermal deformation, it directly or indirectly acts on the tripping mechanism, so one end does not set the soft conductor.
[0014] In some embodiments, the thermal element of the non-current overload thermal protection device is laminated by at least two metal materials with different thermal expansion coefficients.
[0015] In the above embodiments, when subjected to heat conduction or heat radiation of the insulating shell or / and internal elements, the metal layer with high thermal expansion coefficient will bend towards the metal layer with low thermal expansion coefficient, and directly or indirectly drive the tripping mechanism to trip the switch, and the movable contact device and the static contact device are electrically separated.
[0016] In some embodiments, the distance between the non-current overload thermal protection device and the tripping mechanism is L1, and the distance between the current overload thermal protection device and the tripping mechanism is L2, L1>L2.
[0017] In some embodiments, the thermal element of the non-current overload thermal protection device is at least 20% lower than the thermal element of the current overload thermal protection device in bending deformation.
[0018] In some embodiments, the driving temperature of the non-current overload thermal protection device is at least 20% higher than the driving temperature of the current overload thermal protection assembly.
[0019] In some embodiments, the driving time of the non-current overload thermal protection device is at least 20% longer than the driving time of the current overload thermal protection device.
[0020] In some embodiments, the resistivity of the non-current overload thermal protection device is at least 20% higher or lower than that of the current overload thermal protection device.
[0021] In the above embodiments, the protection conditions set by the non-current overload thermal protection device and the current overload thermal protection device are described.
[0022] In some embodiments, when the thermal element indirectly drives the tripping mechanism, the non-current overload thermal protection device and the tripping mechanism are provided with a linkage member. When the thermal element is heated and bent, the linkage member is driven, and the linkage member drives the tripping mechanism to electrically separate the movable contact device and the static contact device.
[0023] In the above embodiments, the linkage member transmits the force and movement of the thermal element of the thermal protection device when it is heated and bent. The structure is simple and feasible.
[0024] In some embodiments, when the thermal element directly drives the tripping mechanism, the thermal element of the thermal protection device of non-current overload extends to the tripping mechanism, and when the thermal element is heated and bent, the tripping mechanism is unlocked, and the movable contact device is electrically separated from the static contact device.
[0025] In the above embodiments, the thermal element is heated and bent to directly transmit force and movement to the tripping mechanism.
[0026] The beneficial effects of the present application are:
[0027] 1. The present application increases the protection function of the electrical switch under the condition of overheating caused by non-abnormal current, and can protect the switch in the early stage of abnormal heat to avoid irreversible damage to the switch.
[0028] 2. The protection function provided by the present application can be provided without setting a control unit on the switch, which can greatly reduce the cost.
[0029] 3. The present application directly uses mechanical transmission to trip and disconnect the switch, greatly shortening the action time. BRIEF DESCRIPTION OF DRAWINGS
[0030] In order to more clearly illustrate the technical solutions in the embodiments of the present application or the prior art, the drawings needed to be used in the description of the embodiments or the prior art will be briefly introduced. Obviously, the drawings in the following description are only some embodiments described in the present application, and other drawings can be obtained by those skilled in the art without creative labor.
[0031] Figure 1 The small switch structure with abnormal heating protection function for the first embodiment of the present application;
[0032] Figure 2 The internal specific structure of the small switch with abnormal heating protection function for the first embodiment of the present application;
[0033] Figure 3 The working principle diagram of the first thermal element when the present application protects against abnormal heating;
[0034] Figure 4 The relationship diagram between the first thermal element and the tripping mechanism when the present application protects against abnormal heating;
[0035] Figure 5 The relationship diagram between the second thermal element of the thermal protection device of current overload and the tripping mechanism of the present application;
[0036] Figure 6 The internal specific structure of the small switch with abnormal heating protection function for the second embodiment of the present application;
[0037] Figure 7 This is a structural diagram of a plastic-case switch with abnormal heat protection function according to the third embodiment of the present invention;
[0038] Figure 8 This is a structural diagram of a plastic-cased switch component with abnormal overheating protection function according to the third embodiment of the present invention;
[0039] Figure 9 This is a structural diagram of a plastic-cased switch component with abnormal overheating protection function according to the fourth embodiment of the present invention. Detailed Implementation
[0040] The features and exemplary embodiments of various aspects of the present invention will now be described in detail. Numerous specific details are set forth in the following detailed description to provide a thorough understanding of the invention. However, it will be apparent to those skilled in the art that the invention may be practiced without requiring some of these specific details. The following description of embodiments is merely intended to provide a better understanding of the invention by illustrating examples of the invention. The invention is by no means limited to any specific configurations and algorithms presented below, but covers any modifications, substitutions, and improvements to elements, components, and algorithms without departing from the spirit of the invention. Well-known structures and techniques are not shown in the drawings and the following description in order to avoid unnecessarily obscuring the invention.
[0041] First Embodiment
[0042] As attached Figures 1-5 As shown in the figure, a specific embodiment of the present invention discloses a small switch with abnormal overheating protection function, comprising an insulating shell 10 and internal components 20. The internal components include: a set of thermal protection devices 22 for non-current overload heating, a set of thermal protection devices 23 for current overload, a front power connection device 25, a rear power connection device 26, a moving contact device 27, a stationary contact device 28, a tripping mechanism 21, and an operating mechanism 24. The operating mechanism 24 drives the moving contact device 27 and the stationary contact device 28 to connect and disconnect electricity. The set of thermal protection devices 22 for non-current overload heating and the set of thermal protection devices 23 for current overload are correspondingly arranged in the front power connection device 25 and the rear power connection device 26. Both the thermal protection devices 22 for non-current overload heating and the thermal protection devices 23 for current overload are provided with thermal elements. The thermal elements directly or indirectly drive the tripping mechanism to trip the switch and disconnect the circuit.
[0043] Specifically, the tripping mechanism 21 includes a locking buckle 211, and the operating mechanism 24 includes a trip buckle 241, with the locking buckle 211 and the trip buckle 241 overlapping. The non-current overload heating thermal protection device 22 is installed on the front-end power connection device 25 inside the insulating housing 10. The heating element installed on the non-current overload heating thermal protection device is a first heating element 229, and the root of the first heating element 229 is fixed to the front-end power connection device 25 by welding or riveting. The tip of the first thermal element 229 extends upward, and a linkage 221 is provided between the tip of the first thermal element 229 and the tripping mechanism 21. The linkage 221 and the first thermal element 229 have a slot at their mating position. The tip of the first thermal element 229 is confined within the slot. The first thermal element 229 is laminated from at least two metal materials with different coefficients of thermal expansion. When abnormal heat is generated from the front-end power wiring device 25, such as abnormal pressure between the moving and stationary contacts, increased contact resistance, and the switch being in a loose connection state, a large amount of resistance heat is generated between the moving and stationary contacts. This abnormal heat is conducted to the first thermal element 229 through heat transfer or heat radiation. The metal layer with a high coefficient of thermal expansion will bend towards the metal layer with a low coefficient of thermal expansion. The tip of the overheat protection device bends to the right within the slot of the linkage 221 and pushes the tripping mechanism 21 through the linkage 221 to trip the switch. The moving contact device 27 and the stationary contact device 28 are separated.
[0044] The thermal protection device 23 for current overload is equipped with a second thermal element 231, which is a multi-metal element made of at least two materials with different coefficients of thermal expansion laminated together. The multi-metal element is connected in series in a conductive circuit, with one end connected to the power supply wiring device 26 as a fixed end. The other end is connected to a soft conductor on the moving contact device 27 as a heat-deformable end. When the current flowing through the multi-metal element exceeds the rated current, or when the current flowing through the internal components exceeds the rated current, heat is generated and conducted to the multi-metal element. The metal layer with the high coefficient of thermal expansion of the multi-metal element will bend towards the metal layer with the low coefficient of thermal expansion. The thermal protection device 23 for current overload also includes a pull rod 232. One end of the pull rod 232 is connected to the heat-deformable end of the second thermal element 231, and the other end is located in a slot of the latch 211 on the tripping mechanism 21. When the second heating element 231 is deformed by heat, the force and stroke are transmitted to the latch 211 on the tripping mechanism 21, so that the latch 211 and the jumper 241 are disengaged from each other, and the operating mechanism 24 drives the moving contact device 27 to electrically separate from the stationary contact device 28.
[0045] Further explanation is given of the thermal protection device 22 for non-current overload heating and the thermal protection device 23 for current overload heating. Both use multi-metal heating elements as inductive heat-sensing components. However, they differ in their protection range and technical effects. The thermal protection device 22 protects against abnormal heating regardless of current, primarily in cases of normal current despite abnormal heating. The thermal protection device 23 protects against abnormal current and overload conditions. The heat sources also differ: the heat source for the non-current overload heating device 22 is abnormal heat, while the heat source for the current overload heating device 23 is overload current. Structurally, the heating element in the non-current overload heating device 22 is not electrically connected to the conductor during installation. In the current overload heating device 23, the heating element must be electrically connected to the conductor during installation. Regarding force and stroke transmission characteristics, the heating element in the non-current overload heating device 22 exhibits irregular and rapid changes. In the thermal protection device 23 for current overload, the heating element deforms regularly with the magnitude of the current and time. In this embodiment, the first heating element 229 in the thermal protection device 22 for non-current overload heating is heated by radiation and conduction and does not generate heat itself. The second heating element 231 in the thermal protection device 23 for current overload is both an element that senses heat and a heating element, and the heat source is the overload current.
[0046] The working principle and process of this invention are as follows: The front power supply terminal of this invention is equipped with a non-current overload thermal protection device 22, and the rear power supply terminal is equipped with a current overload thermal protection device 23. Under normal switch and environmental conditions, the current overload thermal protection device 23 protects the switch. When the switch is improperly installed, such as abnormal pressure between the moving and stationary contacts, abnormal deformation, loose terminal screws, or localized fire, abnormal heat will be generated at and around the abnormal location. This abnormal heat will trigger the second heating element 231 on the non-current overload thermal protection device 22. The second heating element 231 deforms, triggering the tripping mechanism 21, and the switch disconnects, thus achieving the protection function. Therefore, more comprehensive protection of the switch can be achieved. The relationship between these two protection components is set as an OR relationship; either condition triggering will achieve protection. Specifically, in terms of mechanical structure, the tripping mechanism 21 triggered by both protection components is the same. The linkage 221 driven by the non-current overload thermal protection device 22, and the tripping mechanism 21, are triggered and can be separated; they do not contact when there is no abnormality, but contact when an abnormality occurs. The linkage 232 driven by the current overload thermal protection device 23, and the tripping mechanism, allows the lever to slide within the groove of the tripping rod. When the electrical switch is closed, the lever 232 is in contact with the right side of the tripping rod. In the event of an overload, the lever 232 contacts the latch 211 through the groove, causing the latch 211 to rotate, breaking the contact between the latch and the tripping latch, thus opening the electrical switch. During normal circuit breaker opening, the lever 232 remains stationary. When the tripping mechanism operates, the groove on the latch 211 moves to the right side of the lever, preventing any force or movement connection between the lever 232 and the tripping mechanism 21. Therefore, protection is provided for any one or both abnormalities. In this invention, both the non-current overload thermal protection device 22 and the current overload protection component 23 include multi-metal heating elements. Therefore, the following priority settings are implemented for their operation: the thermal element drive tripping mechanism 21 of the non-current overload thermal protection device 22 has a bending deformation of at least 20% lower than that of the thermal element of the current overload thermal protection device 23. The temperature of the drive tripping mechanism 21 of the non-current overload thermal protection device 22 is at least 20% higher than the drive temperature of the current overload thermal protection device 23. The drive tripping time of the non-current overload thermal protection device 22 is at least 20% longer than the drive time of the current overload thermal protection device 23. The resistivity of the non-current overload thermal protection device is at least 20% higher or lower than that of the current overload thermal protection device.The distance between the non-current overload thermal protection device and the tripping mechanism can be set as L1, and the distance between the current overload thermal protection device and the tripping mechanism can be set as L2, where L1 > L2. That is, the distance L1 between the first thermal element 229 and the tripping mechanism 21 is greater than the distance L2 between the second thermal element 231 and the tripping mechanism 21. This ensures that under the same tripping conditions, the current overload protection takes priority.
[0047] The electrical switch provided by this invention adds protection against overheating caused by non-abnormal current, making the protection function more comprehensive. It can provide protection in the early stages of abnormal heat, preventing irreversible damage to the switch. The protection function is not limited by the current flow and can be installed at any possible location of abnormal heat. Furthermore, it works in conjunction with the tripping mechanism on the switch via a linkage, resulting in low cost and ease of implementation. The protection function eliminates the need for a control unit on the switch, significantly reducing costs. Compared to the protection functions provided by existing smoke detectors, the cost is significantly lower. The electrical switch directly uses mechanical transmission to trip and disconnect, greatly shortening the action time.
[0048] Second Embodiment
[0049] like Figure 6 As shown, the present invention provides an electrical switch according to a second specific embodiment. The difference from the first embodiment is that the non-current overload heating thermal protection device 22 is disposed on the stationary contact device 28. The root of the first heating element 229 on the device is fixed by welding or riveting and extends to the upper right to the top of the tripping mechanism 21. When the stationary contact device 28 is subjected to abnormal heating caused by the loose connection of the front power wiring device 25 or the moving contact device 27, the first heating element 229 will bend downward and directly push the tripping mechanism 21, causing the switch to trip and the moving contact device 27 to be electrically separated from the stationary contact device 28.
[0050] Of course, since the non-current overload heating thermal protection device 22 described in this invention protects against non-current abnormal heating, any component that may experience abnormal heating can be installed, such as the rear power wiring device 26, the insulating shell 10, or any other component or combination thereof. The principle is that when the non-current overload heating thermal protection device 22 is subjected to heat conduction or heat radiation from the above components and the heat accumulates to an abnormal temperature, the non-current overload heating thermal protection device 22 directly or indirectly drives the tripping mechanism 21 to trip the switch, and the moving contact device 27 and the stationary contact device 28 are electrically separated.
[0051] Third Embodiment
[0052] Please refer to Figures 7 to 8This invention discloses a three-pole molded case switch with abnormal overheating protection function, comprising an insulating shell 10 and internal components 20. The internal components include: a non-current overload overheating thermal protection device 22, a current overload thermal protection device 23, a tripping mechanism 21, an operating mechanism 24, a front-end power connection device 25, a rear-end power connection device 26, a moving contact device 27, a stationary contact device 28, and an arc-extinguishing chamber 29. The operating mechanism 24 drives the moving contact device 27 and the stationary contact device 28 to connect and disconnect electricity. In the A and C phases of the switch, a set of non-current overload overheating thermal protection devices 22 and a set of current overload thermal protection devices 23 are correspondingly installed in the front-end power connection device 25 and the rear-end power connection device 26, respectively. Both the non-current overload overheating thermal protection device 22 and the current overload thermal protection device 23 are equipped with thermal elements, which directly or indirectly drive the tripping mechanism 21 to trip the switch and disconnect the circuit.
[0053] One set of non-current overload thermal protection devices for phases A and C is installed on the stationary contact device 28 of the internal components of the corresponding phases. The front-end power supply wiring device 25 and the stationary contact device 28 are electrically connected and are both conductive components of the front-end power supply wiring section of the switch. The current overload thermal protection device 23, the operating mechanism 24, the front-end power supply wiring device 25, the rear power supply wiring device 26, the moving contact device 27, the stationary contact device 28, and the arc-extinguishing chamber 29 are conventional settings for molded case switches and will not be described in detail here. In this embodiment, the non-current overload thermal protection device 22 is installed on the side phases A and C of the switch. The illustration shows the case where it is installed on phase A. The front-end power supply wiring device 25 is electrically connected to the stationary contact device 28, and the rear power supply wiring device 26 is electrically connected to the moving contact device 27. The current overload thermal protection device 23 is installed on the moving contact conductor. The thermal protection device 22 for non-current overload heating is equipped with a first heating element 229, which is a stamped bimetallic sheet attached to the top of the stationary contact conductor of the stationary contact device 28. The left side of the heating element 229 is fixed to the stationary contact conductor by spot welding or riveting, while the right side has a slot. A linkage 221, also a stamped metal sheet, is located between the right side of the thermal protection device 22 and the tripping mechanism 21. The stationary contact conductor conducts abnormal heat to the heating element 229. The lower edge of the linkage 221 is tightly connected to the right side of the first heating element 229 via a slot. To save space and avoid contact support on the moving contact device, the thickness direction of the linkage 221 is aligned with the front-rear direction of the switch. The upper part of the linkage 221 engages with the tripping rod on the tripping mechanism 21. Abnormal heating of the stationary contact conductor is conducted to the thermal protection device 22. The bimetallic heating element of the thermal protection device will bend upward, and the upward force and displacement are transmitted to the tripping rod on the tripping mechanism 21 through the linkage 221. When the switch generates abnormal heat, it can drive the tripping mechanism 21 to trip the switch, thus achieving the abnormal heat protection function. It should be noted that the tripping mechanism of the electrical fault protection device 23 and the tripping mechanism of the non-current overload heating thermal protection device 22 in this embodiment are the same tripping mechanism. The structure of the non-current overload heating thermal protection device in phase C is the same as that in phase A.
[0054] The working principle and process of this invention are the same as those of the first embodiment.
[0055] Fourth embodiment
[0056] Please refer to Figure 9This invention discloses an electrical switch according to a fourth specific embodiment. Unlike the third embodiment, the thermal protection device 22 for non-current overload heating further includes an adjusting nut 223. The linkage 221 is a shaft-like part with a threaded lower part. The first heating element 229 has a corresponding threaded hole. The lower thread of the linkage 221 engages with the threaded hole on the first heating element 229. The engagement distance between the thermal protection device 22 for non-current overload heating and the tripping mechanism 21 can be adjusted by adjusting the adjusting nut 223 to adapt to various application situations.
[0057] This invention clarifies the scheme and application of a thermal protection device in an electrical switch containing a control unit. The bending output of the thermal element is converted into an electrical signal, which is then recognized and processed by the control device. For example, the thermal protection device in Embodiment 5 can also use the same structure, and is consistent in principle, which is innovative and practical.
[0058] This invention may be implemented in other specific forms without departing from its spirit and essential characteristics. The present embodiments are to be regarded in all respects as exemplary rather than limiting, and the scope of the invention is defined by the appended claims rather than the foregoing description, and all modifications falling within the meaning of the claims and their equivalents are thus included within the scope of the invention.
Claims
1. An electrical switch comprising at least an insulating housing and internal components, said internal components comprising at least: At least one set of thermal protection device of non-current overload heating, one set of thermal protection device of current overload heating, front power connection device, rear power connection device, movable contact device, static contact device, trip mechanism, operating mechanism, the operating mechanism directly or indirectly drives the movable contact device and the static contact device to carry out electrical connection and disconnection; characterized in that: in any one pole of the electric switch, one set of thermal protection device of non-current overload heating and one set of thermal protection device of current overload heating are arranged in the front power connection device and the rear power connection device, or two sets of thermal protection device of non-current overload heating are arranged in the front power connection device and the rear power connection device; the thermal protection device of non-current overload heating and the thermal protection device of current overload heating are both provided with a thermal element, and the thermal element directly or indirectly drives the trip mechanism to act to trip the switch to disconnect the circuit.
2. An electric switch according to claim 1, characterised in that The trip mechanism comprises a lock catch, and the operating mechanism comprises a trip catch, and the lock catch and the trip catch are overlapped.
3. An electric switch according to claim 1, characterised in that A conductor is arranged on one or both ends of the thermal element of the thermal protection device of current overload heating.
4. An electric switch according to claim 1, characterised in that No soft conductor is arranged on one end of the thermal element of the thermal protection device of non-current overload heating.
5. An electric switch according to claim 1, characterised in that The thermal element of the thermal protection device of non-current overload heating is laminated by at least two metal materials with different thermal expansion coefficients.
6. An electric switch according to claim 1, characterised in that The distance between the thermal protection device of non-current overload heating and the trip mechanism is L1, and the distance between the thermal protection device of current overload heating and the trip mechanism is L2, L1>L2.
7. An electric switch according to claim 1, characterised in that The bending deformation amount of the thermal element of the thermal protection device of non-current overload heating is at least 20% lower than that of the thermal element of the thermal protection device of current overload heating.
8. An electric switch according to claim 1, characterised in that The driving temperature of the thermal protection device of non-current overload heating is at least 20% higher than that of the thermal protection device of current overload heating.
9. An electric switch according to claim 1, characterised in that The driving time of the thermal protection device of non-current overload heating is at least 20% longer than that of the thermal protection device of current overload heating.
10. An electric switch according to claim 1, characterised in that The resistivity of the thermal protection device of non-current overload heating is at least 20% higher or lower than that of the thermal protection device of current overload heating.
11. An electric switch according to claim 1, characterised in that When the thermal element indirectly drives the trip mechanism, a linkage is arranged between the thermal protection device of non-current overload heating and the trip mechanism, and when the thermal element is heated and bent, the linkage is driven, the linkage drives the trip mechanism to electrically separate the movable contact device and the static contact device.
12. An electric switch according to claim 1, characterised in that When the thermal element directly drives the trip mechanism, the thermal element of the thermal protection device of non-current overload heating extends to the vicinity of the trip mechanism, and when the thermal element is heated and bent, the trip mechanism is unlocked, and the movable contact device and the static contact device are electrically separated.