Processing method and binding process for badness of resettable thermal protector connected with motor

Abstract

The invention discloses a processing method and a binding process for a poor motor connected resettable thermal protector. The processing method mainly comprises the following four steps: (1) sorting a poor thermal protector assembly; (2) performing high-voltage test; (3) short circuit current testing; (4) detecting a motor stator or a finished motor which cannot determine whether the thermal protector is subjected to destructive pressure or not; the binding process mainly comprises the following three steps: (1) preparation before binding; (2) connecting and binding the thermal protector; (3) other requirements of binding of the thermal protector are met; according to the invention, the stator with poor resistance value does not need to be completely dismantled based on test, the resistance value of the stator winding after high-voltage repair meets the test requirement, and the repair time and energy consumption are saved; based on the fact that residual deformation does not occur in the bimetallic strip of the thermal protector in actual use, and the total stress applied to the bimetallic strip does not exceed the use stress, enterprises in the motor industry are guided to formulate an effective thermal protector binding process through evaluation.

Description

Technical Field

[0001] The invention relates to the technical field of motor protector testing, and in particular to a method for processing a motor resetting thermal protector failure and a wrapping process. Background Art

[0002] Household appliances and general industrial motors strive to be safe and designed in accordance with safety regulations. In order to prevent overheating and overcurrent, thermal protectors are used. The stator comprehensive tester sets the test steps as follows: resistance test, inter-turn insulation test, polarity or rotation test, insulation resistance test and high voltage test, i.e. electrical strength test. The five test steps are collectively referred to as insulation safety test according to the established procedures. Generally, the factory inspection of thermal protectors includes electrical strength test, resistance test and performance test in accordance with GB / T13002 and GB / T22762. In the actual inspection process of motor industry enterprises, it is always randomly detected that the first step is that the resistance value exceeds the upper limit. The main reason for the analysis is that there is dust and tiny oxide film on the surface of the thermal protector contact, resulting in poor contact and large contact resistance. Therefore, the test efficiency is low, resulting in the accumulation of test quantity. The technicians artificially relax the resistance specifications at the winding end of the thermal protector section, but the effect is minimal. The relaxation of the specifications is too large to detect the true resistance value of the winding, which poses a potential risk. When the contact resistance value of the thermal protector relaxed by 2 to 5 times still cannot meet the test requirements, another one will be selected. One way is to take the stator winding assembly of the defective thermal protector and put it in the oven without exceeding its rated operating temperature T-25℃ and bake it for 30 minutes, then cool it and test it again until it passes. If it still does not meet the requirements, it will be dismantled and scrapped as defective. The other way is to directly dismantle it and scrap it as defective, or rework and replace the thermal protector and retest it until it passes.

[0003] Secondly, in the motor industry, in order to ensure that the thermal protector fully contacts the winding, the tension is too large when tying the iron or nylon tie, or the process of tightening the thermal protector tension is not effectively controlled. The thermal protector may be subjected to destructive pressure, deformation of the temperature sensing surface, deformation of the thermal protector cavity and deformation of the bimetallic strip inside the thermal protector shell, which leads to a reduction in the volume of the thermal cavity inside the thermal protector shell, and partially changes the matching relationship between the shell, heating wire and bimetallic strip in the initial design of the thermal protector. The matching problem between the thermal protector shell (thermal cavity), heating wire and bimetal is a set of contradictory unity. Any change among the three can change the initial design parameters of the thermal protector. In short, any change among the three can design a new thermal protector. The action of the thermal protector, that is, the change among the three, leads to a decrease in the action temperature or premature disconnection of the rated design disconnection current, and even the inability to accurately lock the action once and requires a secondary action lock. It will reduce the service life of the bimetallic strip, resulting in a reduction in the protective function or complete loss. Due to the inability to control risks, the degree of damage to the thermal protector cannot be effectively assessed, leading to mass scrapping. At present, motor industry companies have not formulated a process for how to correctly wrap the thermal protector and are in a blind spot. GB 13232, 7.1.1, states that the stress generated by winding processing and treatment, that is, the thermal protector and its connecting wires (including insulation) should be able to withstand certain conditions without changing its action characteristics, but there is no specific mechanical stress and how to avoid mechanical stress damage to the thermal protector.

[0004] In view of the above problems, the present invention provides a method for processing a defective resettable thermal protector of a motor and a wrapping process. Summary of the invention

[0005] The purpose of the invention is to provide a method for processing a defective resettable thermal protector of a motor and a wrapping process.

[0006] The above technical objectives of the present invention are achieved through the following technical solutions:

[0007] A method for processing a faulty resettable thermal protector of a motor, comprising the following steps:

[0008] (1): Sorting out defective thermal protector components: Use a stator comprehensive tester to test the wiring of the thermal protector components, and sort out and analyze the thermal protector components whose test resistance exceeds the upper limit.

[0009] (2): High-voltage test: debug a high-voltage tester, set the maximum voltage threshold to 2500V, pick out the rated working voltage of the thermal protector assembly according to step (1) and set the short-circuit voltage value for high voltage. Short-circuit the defective thermal protector with high voltage, and short-circuit the high voltage no more than 3 times. Use an electronic digital display milliohmmeter to test the resistance value of the thermal protector assembly. If the resistance value meets the set specification requirements, perform a comprehensive stator test, and then perform the next process test, and add color marks for traceability. If the assembly resistance value still exceeds the limit, use step (3) for testing.

[0010] (3): Short-circuit current test: According to the characteristic curve of the thermal protector component in step (2), debug a DC constant current power supply tester, short-circuit the thermal protector component, adjust the short-circuit current, set the power-on time, and read the voltage value; the DC constant current value passed through the thermal protector component must be less than the current value of the thermal protector disconnection current, and set the minimum disconnection time to T min and disconnection maximum time T max , unit is second; after the corresponding condition test, when the surface of the thermal protector component returns to the temperature of 25±5℃, use the electronic digital display milliohmmeter to test its resistance; if the resistance value meets the set specification requirements, the stator comprehensive test is carried out, the component adopts the voltage test, and adds color marks for traceability. This color needs to be different from the color of the component that has undergone high-voltage test, and then the next process test is carried out; for the thermal protector component that directly disconnects within the set time during the short-circuit current test, it needs to be picked out and handed over to the technician for analysis and processing. The technician analyzes and re-applies the DC constant current test three times, and records the three power-on times. If it is not disconnected within the set time, it can be regarded as a qualified product, otherwise it is judged as a defective product.

[0011] (4) Testing of motor stators or finished motors where it is not possible to determine whether the thermal protector is under destructive pressure: 100% test its rated design disconnection current, set the rated design disconnection current value of the thermal protector to be tested, test voltage, set the power-on time, and set the minimum test disconnection time to increase by 3 seconds, that is, T min +3sec, maximum disconnection time T max Setting remains unchanged; disconnection time is less than T min Stators or motors with a disconnection time of more than 3 seconds are considered defective and scrapped. min The stator or motor finished product with a time of +3 sec is judged as good and marked with a mark different from steps (2) and (3) for easy traceability.

[0012] Further, the short - circuit high - voltage test requirements for the thermal protector component in step (2) above are as follows: When the rated operating voltage of the thermal protector is less than 100V, the set short - circuit high voltage is 500V + 2U; when the rated operating voltage of the thermal protector is 100 < U < 150V, the set short - circuit high voltage is 1250V; when the rated operating voltage of the thermal protector U > 150V, the set short - circuit high voltage is 1000V + 2U; where U is the rated operating voltage of the thermal protector.

[0013] Further, in step (3) above, the short - circuit current utilizes the locked - rotor characteristic of the thermal protector, and evaluates the breaking current by inputting a certain voltage, and sets the short - circuit current based on this.

[0014] Further, in step (3) above, the rated current and voltage capacity of the DC constant - current power supply are more than 4 times the rated designed breaking current capacity of the thermal protector to be tested.

[0015] Specifically, for the temperature - type thermal protector component, when connecting the DC constant - current and the input time, take the smaller value, and the maximum short - circuit current does not exceed 70% of its designed rated breaking current.

[0016] Specifically, for the current - type thermal protector component, when connecting the DC constant - current, take the larger value of the input time, and the maximum short - circuit current does not exceed 60% of its designed rated breaking current.

[0017] Specifically, for the temperature - and - current dual - insurance type thermal protector component, when connecting the DC constant - current, take the intermediate value of the input time, and the maximum short - circuit current does not exceed 50% of its designed rated breaking current.

[0018] Specifically, for the temperature - and - current dual - insurance type thermal protector component with an internal heating wire, when connecting the DC constant - current, take the intermediate value of the input time, and the maximum short - circuit current does not exceed 40% of its designed rated breaking current.

[0019] A wrapping process for a motor connected to a reset thermal protector includes the following steps:

[0020] (1) Preparation before wrapping: The lead connection wire of the thermal protector uses a cold - press connection method or an arc - welding method. When using the arc - welding method, the welding current shall not pass through the thermal protector; when directly dipping the connection wire opening of the thermal protector in tin, ensure that the length of the connection wire is not less than 6mm, the dipping time is 2s, and the temperature of the small tin furnace is controlled at 390 ± 30°C.

[0021] (2) Connection and wrapping of the thermal protector: Use a nylon cable tie gun to control the tension at 20 to 25N, and tie the cable tie material at a safe distance of more than 6mm from the connection wire of the thermal protector. When bending the lead wire, it should be bent from a part more than 6 millimeters from the root; when bending, do not damage the root and the lead wire, and do not forcibly pull, squeeze, twist the lead wire or apply lateral tension to damage the thermal protector.

[0022] (3) Other requirements for thermal protector wrapping: meet the requirements of GB 13232 General Rules for Built-in Thermal Protectors for Rotating Motors; the motor wrapped with thermal protectors meets the requirements of GB12350 for abnormal tests.

[0023] Specifically, the wrapping of a single temperature thermal protector: first wrap it with a layer of insulating tape of the corresponding thermal grade, and then wrap it with iron ties or knitted fiber cotton thread.

[0024] Specifically, the wrapping of the current-protective thermal protector: first wrap a layer of insulating tape of the corresponding thermal grade, and then use a cable tie made of thermoplastic material such as nylon cable ties to tie the connecting wire at the end of the thermal protector. Do not wrap it on the thermal protector shell. The thermal protector can also be regarded as a connecting wire to replace the motor lead without wrapping.

[0025] Specifically, the wrapping of the temperature and current dual insurance type automatic reset thermal protector: first wrap a layer of insulating tape of the corresponding thermal grade, and then use iron ties and nylon ties of the corresponding thermal grade and other thermoplastic materials. The iron ties are used for fastening, and the nylon ties of the corresponding thermal grade and other thermoplastic materials are used for auxiliary structure wrapping.

[0026] Specifically, the wrapping of the temperature and current dual insurance type manual reset thermal protector: first wrap a layer of insulating tape of the corresponding thermal grade, and then use iron ties and knitted fiber cotton thread to wrap it. The iron ties are for fastening, and the knitted fiber cotton thread wrapping ties are for auxiliary structural wrapping.

[0027] Specifically, the ultrasonically riveted, pressure-immersed or vacuum-immersed thermal protector is wrapped: first wrap a layer of insulating tape of the corresponding thermal grade, and then use iron ties and knitted fiber cotton thread to wrap, the iron ties are for fastening, and the knitted fiber cotton thread wrapping ties are for auxiliary structural wrapping.

[0028] Furthermore, the folded opening of the thermal protector wrapping is facing outwards and a certain safety distance is controlled.

[0029] In summary, the present invention has the following beneficial effects:

[0030] 1. Stators with poor resistance values ​​do not need to be 100% dismantled. After high voltage repair, the resistance value of the stator winding meets the test requirements, saving repair time and energy consumption.

[0031] 2. According to the characteristic curve of the thermal protector assembly, based on the rule that the rated disconnect current is reduced due to the deformation of the thermal bimetallic strip, 100% detection of the rated design disconnect current can be adopted. Combined with the characteristics of the reduced action temperature, the risk can be fully evaluated and controlled, and scrap can be reduced. Under the premise of controllable quality and ensuring the user's safe actual life, the loss cost of the thermal protector can be reduced, and the testing efficiency can be improved, thereby providing an effective rework method.

[0032] 3. Based on the fact that in actual use, the bimetal sheet of the thermal protector should not undergo residual deformation, the total stress applied to the bimetal should not exceed the service stress. Guide enterprises in the motor industry to formulate an effective thermal protector wrapping process through evaluation, eliminate potential risks that damage the thermal protector, formulate a reasonable pressure applied to the thermal protector, define the safe distance for wrapping the extended wire of the thermal protector, standardize the connection method of the thermal protector, and promote and facilitate enterprises in the motor industry to formulate the correct process for wrapping the thermal protector. Specific implementation manners

[0033] The following further elaborates on the present invention. The technical solutions in the embodiments of the present invention are clearly and completely described. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative efforts belong to the scope of protection of the present invention.

[0034] Embodiment 1

[0035] A method for dealing with defective motor connection of a resettable thermal protector. Test the resettable thermal protector assembly for the motor stator connection (hereinafter all referred to as the assembly). Take the assembly to debug the stator comprehensive tester, set the upper and lower limit specifications of the resistance test according to the process specifications, collect the inter-turn insulation waveform, set the polarity or rotation direction, set the insulation resistance specification, and set the high-voltage test voltage (dielectric strength test). Conduct the component wiring test. If the measured resistance exceeds the upper limit, pick it out for analysis. If the analysis shows that the contact resistance of the thermal protector is large and the resistance value of a single winding is within the specification range, promptly take out the component and perform the following operations:

[0036] Step 1: Debug a high-voltage tester with a maximum set voltage threshold of 2500V. Set the short-circuit voltage value for applying high voltage according to the rated working voltage of the motor of the component. Apply high voltage to short-circuit the thermal protector of the defective stator winding, and the short-circuit high voltage should not exceed 3 times. Specifically, when the rated working voltage of the thermal protector is less than 100V, set the short-circuit high voltage to 500V + 2U (U is the rated working voltage, the same below); when the rated working voltage of the thermal protector is 100 < U < 150V, set the short-circuit high voltage to 1250V; when the rated working voltage of the thermal protector is U > 150V, set the short-circuit high voltage to 1000V + 2U. Each component can be tested for short-circuit high voltage 3 times, and then use an electronic digital display milliohm meter to measure the resistance value of the component. If the resistance value meets the set specification requirements, conduct the stator comprehensive test. Completing the five test steps and testing according to the established procedure are collectively referred to as the insulation safety test, and then conduct the next process test and mark it with a color for traceability. When the resistance value of the component still exceeds the limit, then use the second step for testing:

[0037] Step 2: When the solution in step 1 still cannot meet the resistance value test specifications, according to the characteristic curve of the thermal protector series, provide a large DC constant current power supply tester, which can directly adjust the short-circuit current (utilize the thermal protector's stall characteristics and evaluate the disconnection current by inputting a certain voltage), set the power-on time, read the voltage value, and short-circuit the thermal protector. The ampere capacity value is selected according to the design rated disconnection current of the thermal protector. The rated current and voltage capacity of the selected large DC constant current power supply need to be greater than 4 times the rated design disconnection current of the thermal protector to be tested to avoid damage to the DC constant current power supply tester. The current value of the DC constant current passed into the thermal protector must be less than the current value of the thermal protector disconnection current, and the minimum disconnection time is specified as T. min The maximum disconnection time is T max , in seconds. When the DC constant current power supply does not have the function of setting the power-on time, it is necessary to connect a control box that can control the time of the current. The functions include but are not limited to the following auxiliary functions: upper and lower limit power-on time settings, actual test time display, to ensure the accuracy of the power-on time, which needs to be accurate to milliseconds. Statistics settings for qualified and defective products, warning buzzer alarm function for qualified and defective products, and traffic light warning display.

[0038] Specifically, the temperature type thermal protector is connected with a DC constant current and a smaller value of the switching time, and the maximum short-circuit current does not exceed 70% of its design rated disconnection current.

[0039] Specifically, the current type thermal protector can be connected to a DC constant current input time with a maximum value, and the maximum short-circuit current does not exceed 60% of its design rated disconnection current.

[0040] Specifically, the temperature and current dual insurance thermal protector is connected to a DC constant current input time that takes an intermediate value, and the maximum short-circuit current does not exceed 50% of its designed rated disconnection current.

[0041] Specifically, the temperature and current dual insurance type with a built-in heating wire thermal protector is connected to a DC constant current input time that takes an intermediate value, and the maximum short-circuit current does not exceed 40% of its designed rated disconnection current.

[0042] After the corresponding condition test, wait until the surface of the component returns to the ambient temperature of 25±5℃ and then use the electronic digital display milliohmmeter to test its resistance. If the resistance value meets the set specification requirements, the stator comprehensive test is carried out. The completion of the five test steps and the test according to the established procedures are collectively called insulation safety test. The components are tested by voltage input and marked with color for traceability. This color needs to be different from the color of the components that have been tested by high voltage before the next process test is carried out.

[0043] The test will generate continuous heat and require debugging and safety confirmation by an electrician before operation. For components whose thermal protectors are directly disconnected within the set time during the short-circuit current test, they need to be picked out and handed over to technicians for analysis and processing. The technicians will analyze and re-apply the DC constant current test three times and record the three power-on times. If it is not disconnected within the set time, it can be considered a qualified product, otherwise it is considered a defective product.

[0044] If the test cannot determine whether the thermal protector is under destructive pressure on the motor stator or finished motor, a 100% test of its rated design disconnect current is implemented (using the thermal protector's stall characteristics to evaluate the disconnect current by inputting a certain voltage). According to the characteristic curve of the thermal protector series, the rated current and voltage capacity of the selected large DC constant current power supply needs to be more than 4 times the rated design disconnect current of the thermal protector to be tested to avoid damage to the DC constant current power supply tester. Set the rated design disconnect current value of the thermal protector to be tested, the test voltage, set the power-on time, and set the minimum test disconnect time to increase by 3 seconds, that is, T min +3sec, maximum disconnection time T max The settings remain unchanged, and the actual test time is displayed. The time unit is accurate to milliseconds. The statistics of qualified and defective products are set. The warning buzzer alarm function for qualified and defective products is combined with the traffic light warning display. The disconnection time is less than T min Products with a disconnection time greater than T min The stator or motor finished product with +3sec is judged as good quality and marked with a different mark from the above for easy traceability.

[0045] In order to verify whether the motor assembled after the thermal protector has been tested with high voltage short circuit and DC voltage is applied can meet the customer's safe use and GB / T13002, GB 13232 and GB 12350 requirements, the following thermal protector components are assembled into motors for blocking test. After 30pcs of motors are assembled with automatic reset thermal protector components after high voltage short circuit test, they are blocked for 18 days, and the actual test action cycle is greater than 2500 times to be qualified; after 30pcs of motors are assembled with manual reset thermal protector components, they are blocked for 200 times in each actual test action cycle to be qualified; after 30pcs of motors are assembled with automatic reset thermal protector components, they are blocked for 18 days, and the actual test action cycle is greater than 2500 times to be qualified; 50,000 motors assembled with thermal protectors that have been centrally tested are traced through color markings, and no customer complaints about thermal protectors have been found.

[0046] Embodiment 2

[0047] A wrapping process for a motor-connected resettable thermal protector comprises the following steps:

[0048] (1) Preparation before wrapping: The lead connection wires of the thermal protector are cold-pressed or arc-welded. When arc welding is used, the welding current must not pass through the thermal protector, otherwise excessive current will pass through the thermal protector contacts, causing functional damage to the thermal protector contacts; when the opening of the thermal protector connection wire is directly tinned, ensure that the connection wire length is not less than 6mm, the tinning time is 2s, and the temperature of the small tin furnace is controlled at 390±30℃. Shorter connection wire length and longer tinning time will cause potential poor contact hazards of the thermal protector.

[0049] (2) Connection and wrapping of thermal protectors: Use a nylon tie gun to control the tension at 20 to 25N. Tie the tie material at a safe distance of 6mm from the thermal protector connection line. When bending the lead wire, bend it from a part that is more than 6mm away from the root. When bending, do not damage the root and lead wire. Do not forcibly pull, squeeze, twist the lead wire, or use lateral tension to damage the thermal protector. Avoid lateral tension to damage the thermal protector. It is not advisable to directly use tools without pressure tension control, such as pliers, to tie the tie, as the tension cannot be controlled. Do not use sharp tools to touch the thermal protector, and do not hit or impact the thermal protector.

[0050] (3) Other requirements for thermal protector wrapping: meet the requirements of GB 13232 General Rules for Built-in Thermal Protectors for Rotating Motors; the motor wrapped with thermal protectors meets the requirements of GB12350 for abnormal tests. For thermal protectors that sense ambient temperature and are fixed inside the stator or motor, only the thermal protector fixing and electrical strength requirements need to be evaluated.

[0051] Specifically, the wrapping of a single temperature thermal protector: first wrap it with a layer of insulating tape of the corresponding thermal grade, and then wrap it with iron ties or knitted fiber cotton thread.

[0052] Specifically, the wrapping of the current-protective thermal protector: first wrap a layer of insulating tape of the corresponding thermal grade, and then use a cable tie made of thermoplastic material such as nylon cable ties to tie the connecting wire at the end of the thermal protector. Do not wrap it on the thermal protector shell. The thermal protector can also be regarded as a connecting wire to replace the motor lead without wrapping.

[0053] Specifically, the wrapping of the temperature and current dual insurance type automatic reset thermal protector: first wrap a layer of insulating tape of the corresponding thermal grade, and then use iron ties and nylon ties of the corresponding thermal grade and other thermoplastic materials. The iron ties are used for fastening, and the nylon ties of the corresponding thermal grade and other thermoplastic materials are used for auxiliary structure wrapping.

[0054] Specifically, the wrapping of the temperature and current dual insurance type manual reset thermal protector: first wrap a layer of insulating tape of the corresponding thermal grade, and then use iron ties and knitted fiber cotton thread to wrap it. The iron ties are for fastening, and the knitted fiber cotton thread wrapping ties are for auxiliary structural wrapping.

[0055] Specifically, the thermal protector wrapped by ultrasonic riveting, pressure immersion or vacuum immersion: first wrap a layer of insulating tape of the corresponding thermal grade, then use iron tie and knitted fiber cotton thread to wrap, iron tie is for fastening, knitted fiber cotton thread wrapping tie is for auxiliary structure wrapping. Thermal protectors with PTC (manual reset) cannot be immersed, otherwise the PTC will fail due to poor contact. Completely sealed thermal protectors can be immersed.

[0056] Furthermore, the folded opening of the thermal protector wrapping is facing outwards and a certain safety distance is controlled.

[0057] For the component wrapping that has been applied with thermal conductive glue or thermal conductive sheet before connecting the thermal protector, the thermal protector is directly close to the component, and it is wrapped with iron ties and knitted fiber cotton thread. The iron ties are used for fastening, and the knitted fiber cotton thread ties are used for auxiliary structural wrapping.

[0058] For motors that use the temperature characteristics of thermal protectors, in order to obtain better surface contact with the temperature-sensing surface of the thermal protector for the stator being processed, the winding end face of the thermal protector needs to be reshaped, and then a fake thermal protector entity that is easy to remove is connected after the shaping. After the subsequent stator processing, it is removed and then the real thermal protector is connected; shaping without the thermal protector.

[0059] Implementation Three

[0060] Take a motor stator connected to the current and temperature dual insurance type manual reset thermal protector for experiment:

[0061] Design specifications: disconnection temperature: 127~143℃, reset temperature: 65~85℃;

[0062] Disconnect current: 20.4A, 4-15s disconnection, 15VDC, 25℃.

[0063] The experimental results are shown in the following Appendix 1, Appendix 2 and Appendix 3:

[0064] Appendix 1, check the disconnection temperature and reset temperature characteristics of the thermal protector:

[0065]

[0066] Conclusion: After simulating mechanical pressure deformation, the disconnection temperature of the simulated sample decreased and exceeded the design range. It was 16.48℃ lower than the disconnection temperature without mechanical pressure deformation on average, and the reset temperature decreased slightly.

[0067] Appendix 2, check the thermal protector disconnect current characteristics (using the thermal protector blocking characteristics):

[0068]

[0069] Appendix 3, check the thermal protector disconnect current characteristics (using the thermal protector blocking characteristics):

[0070]

[0071] Conclusion: Referring to Appendix 2, after simulating mechanical pressure deformation, the disconnection time of the simulated sample decreased, which was 5.68 seconds shorter than the disconnection time of the sample that was not subjected to mechanical pressure deformation on average; referring to Appendix 3, after simulating mechanical pressure deformation, the disconnection time of the simulated sample decreased, which was 7.0 seconds shorter than the disconnection time of the sample that was not subjected to mechanical pressure deformation on average. It can be inferred that the greater the pressure and the lateral tension on the thermal protector, the greater the degree of damage to its own temperature and current characteristics, the lower the operating temperature and the sharp decrease in the current disconnection time until the function is completely lost; in short, when the thermal protector is subjected to abnormal pressure or tension, it will destroy the initial design of the thermal protector, that is, the matching relationship between the shell, heating wire, and bimetallic strip, which will naturally affect the temperature protection or current protection function of the initial design of the thermal protector.

[0072] This specific embodiment is merely an explanation of the present invention and is not a limitation of the present invention. After reading this specification, those skilled in the art may make non-creative modifications to the present embodiment as needed. However, as long as they are within the scope of the claims of the present invention, they are protected by the patent law.

Claims

1. A method for handling a faulty motor connection resettable thermal protector, characterized in that: It includes the following steps: (1): Sort out defective thermal protector components: Connect the thermal protector components to a stator comprehensive tester for wiring test, and pick out and analyze the thermal protector components with test resistance exceeding the upper limit. (2): High-voltage test: Debug a high-voltage tester, set the maximum voltage threshold to 2500V, set the short-circuit voltage value for high-voltage application according to the rated working voltage of the thermal protector components picked out in step (1), apply high voltage to the short-circuited defective thermal protectors, with the short-circuit high voltage not exceeding 3 times. Use an electronic digital display milliohm meter to test the resistance value of the thermal protector components. If the resistance value meets the set specification requirements, then conduct a stator comprehensive test, and then conduct the next process test and mark it with a color for traceability. When the component resistance value still exceeds the limit, then use step (3) for testing. (3): Short-circuit current test: According to the characteristic curve of the thermal protector component in step (2), debug a DC constant current power supply tester, short-circuit the thermal protector component, adjust the short-circuit current, set the power-on time, and read the voltage value; the DC constant current value passed through the thermal protector component must be less than the current value of the thermal protector disconnection current, and set the minimum disconnection time to T min and disconnection maximum time T max , unit: seconds; After the corresponding condition test, wait until the surface of the thermal protector component returns to a temperature of 25 ± 5°C, and then use an electronic digital display milliohm meter to test its resistance value. If the resistance value meets the set specification requirements, conduct a stator comprehensive test. The component is tested by applying voltage and marked with a color for traceability. This color needs to be different from that of the components that have undergone high-voltage tests, and then conduct the next process test. For the thermal protector components whose thermal protectors directly disconnect within the set time during the short-circuit current test, they need to be picked out and handed over to technical personnel for analysis and processing. The technical personnel analyze and apply a direct current constant current again for three tests, and record the three power-on times. If it does not disconnect within the set time, it can be regarded as a qualified product, otherwise it is determined as a defective product. (4) Testing of motor stators or finished motors where it is not possible to determine whether the thermal protector is under destructive pressure: 100% test its rated design disconnection current, set the rated design disconnection current value of the thermal protector to be tested, test voltage, set the power-on time, and set the minimum test disconnection time to increase by 3 seconds, that is, T min +3sec, maximum disconnection time T max Setting remains unchanged; disconnection time is less than T min Stators or motors with a disconnection time of more than 3 seconds are considered defective and scrapped. min The stator or motor finished product with a time of +3 sec is judged as good and marked with a mark different from steps (2) and (3) for easy traceability.

2. A method for handling a faulty motor connection resettable thermal protector according to claim 1, characterized in that: The requirements for short-circuit high-voltage test of the thermal protector components in step (2): When the rated working voltage of the thermal protector is less than 100V, set the short-circuit high voltage to 500V + 2U; when the rated working voltage of the thermal protector is 100 < U < 150V, set the short-circuit high voltage to 1250V; when the rated working voltage of the thermal protector U > 150V, set the short-circuit high voltage to 1000V + 2U; where U is the rated working voltage of the thermal protector.

3. A method for handling a faulty motor connection resettable thermal protector according to claim 1, characterized in that: In step (3), the short-circuit current utilizes the locked-rotor characteristic of the thermal protector, and evaluates the breaking current by inputting a certain voltage, and sets the short-circuit current based on this.

4. A method for handling a faulty motor connection resettable thermal protector according to claim 1, characterized in that: In step (3), the direct current constant current power supply has a rated current and voltage capacity greater than 4 times the rated design breaking current of the thermal protector to be tested.

5. A method for dealing with defects of a motor-connected resettable thermal protector according to claim 1, characterized in that: For the temperature-type thermal protector component, the minimum value of the connected direct current constant current and the power-on time is taken, and the maximum short-circuit current does not exceed 70% of its designed rated breaking current; For the current-type thermal protector component, the maximum value of the connected direct current constant current power-on time is taken, and the maximum short-circuit current does not exceed 60% of its designed rated breaking current; For the temperature and current double-insurance type thermal protector component, the intermediate value of the connected direct current constant current power-on time is taken, and the maximum short-circuit current does not exceed 50% of its designed rated breaking current; For the temperature and current double-insurance type thermal protector component with an internal heating wire, the intermediate value of the connected direct current constant current power-on time is taken, and the maximum short-circuit current does not exceed 40% of its designed rated breaking current.

6. A wrapping process for a motor-connected resettable thermal protector, characterized in that: It includes the following steps: (1) Preparation before wrapping: The lead connection wire of the thermal protector is cold-pressed or arc-welded. When arc welding is used, the welding current must not pass through the thermal protector; when the opening of the thermal protector connection wire is directly tinned, ensure that the connection wire length is not less than 6mm, the tinning time is 2s, and the temperature of the small tin furnace is controlled at 390±30℃; (2) Connection and wrapping of thermal protectors: Use a nylon tie gun to control the tension at 20 to 25N. Tie the tie material at a safe distance of 6mm from the thermal protector connection line. When bending the lead wire, bend it from the part that is more than 6mm away from the root. When bending, do not damage the root and lead wire. Do not forcibly pull, squeeze, twist the lead wire, or use lateral tension to damage the thermal protector. (3) Other requirements for thermal protector wrapping: meet the requirements of GB 13232 General Rules for Built-in Thermal Protectors for Rotating Motors; the motor wrapped with thermal protectors meets the requirements of GB12350 for abnormal tests.

7. A wrapping process for a motor-connected resettable thermal protector according to claim 6, characterized in that: Wrapping of single temperature thermal protector: first wrap a layer of insulating tape of corresponding thermal grade, then wrap it with iron tie or knitted fiber cotton thread; Wrapping of current-protective thermal protectors: first wrap a layer of insulating tape of the corresponding thermal grade, and then use a nylon tie or other thermoplastic material to tie the connecting wire at the end of the thermal protector. Do not wrap it on the thermal protector shell. The thermal protector can also be regarded as a connecting wire to replace the motor lead without wrapping. Wrapping of temperature and current dual insurance type automatic reset thermal protector: first wrap a layer of insulating tape of the corresponding thermal grade, then use iron tie ties and nylon tie ties of the corresponding thermal grade and other thermoplastic material tie ties. The iron tie ties are used for fastening, and the nylon tie ties of the corresponding thermal grade and other thermoplastic material tie ties are used for auxiliary structure wrapping; The wrapping of the temperature and current dual insurance type manual reset thermal protector: first wrap a layer of insulating tape of the corresponding thermal grade, then use iron tie and knitted fiber cotton thread to wrap, the iron tie is for fastening, and the knitted fiber cotton thread wrapping tie is for auxiliary structure wrapping; Ultrasonic riveted, pressure immersed or vacuum immersed thermal protector wrapping: first wrap a layer of insulating tape of the corresponding thermal grade, and then use iron ties and knitted fiber cotton thread to wrap, the iron ties are for fastening, and the knitted fiber cotton thread wrapping ties are for auxiliary structural wrapping.

8. A wrapping process for a motor-connected resettable thermal protector according to claim 7, characterized in that: The closing position of the thermal protector wrapping should be folded outwards and a certain safety distance should be maintained.

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