Residual voltage testing method

Abstract

The invention discloses a residual voltage test method. The method comprises the following steps: connecting a sample power supply binding post on a tester panel to a working power supply of test equipment; a power plug of a tested electric appliance is connected with a socket on a tester panel through a time difference circuit breaker, and correct connection of a test loop is ensured; presetting test waiting time and grounding pin lagging disconnection time; pressing a power-on button of the tester to enable the tested electric appliance to be connected with a working power supply; enabling the tested electric appliance to run for a proper period of time to reach a stable state; and a measuring button of the tester is pressed down, and the working power supply and the ground of the tested electric appliance are sequentially disconnected according to the preset grounding pin lagging disconnection time. According to the method, the real plug breaking process is simulated, that is, the live wire and the zero wire are disconnected firstly, and then the grounding pin is disconnected in a delayed manner, so that the residual voltage of the electric appliance after power failure is measured more accurately. The method not only can ensure the accuracy of the test result, but also can improve the reliability of safety performance evaluation of the electrical equipment.

Description

Technical Field

[0001] The present invention relates to the technical field of electrical equipment detection, and particularly relates to a method for testing residual voltage. Background Art

[0002] The application of residual voltage testing is very extensive in various fields such as low-voltage electrical appliances, household appliances, and medical electrical equipment. By detecting the residual voltage on the voltage terminals of the electrical appliance after power-off, it is possible to evaluate whether its safety and performance meet the requirements of the corresponding standards.

[0003] According to the provisions of the national standards GB9706.1-2020 "Medical Electrical Equipment - Part 1: General Requirements for Safety" and Article 22.5 of GB4706.1 "Safety of Household and Similar Electrical Appliances - Part 1: General Requirements for Safety", all equipment connected to the power supply network through a plug must be designed such that no voltage should exist between the power pins within 1 second after unplugging the plug. This requirement aims to ensure that no dangerous high voltage remains inside the equipment after power-off, thereby protecting users from the potential threat of electric shock. For medical electrical equipment, the specified value shall not exceed 60V; for household and similar electrical appliances, the specified value is usually not more than 34V.

[0004] Given that the test time of 1 second specified by the standard is too short, it is impossible to first unplug the plug and then separately test the voltage of each power pin when actually performing the residual voltage test. Therefore, in actual operation, the residual voltage test device is usually connected while keeping the electrical appliance plug connected to the socket for the experiment.

[0005] However, considering that the main function of the grounding pin (ground wire) is to protect the safety of the electrical appliance and the user. It connects the metal shell of the electrical appliance and finally connects to the ground to prevent electric shock when an electrical fault occurs and the current passes through the human body. Therefore, the grounding pin is usually designed to be longer than the live wire and neutral wire pins. During the actual plug unplugging process, the live wire pin and the neutral wire pin will be unplugged first, and the grounding pin will be unplugged last. The existing residual test methods do not take this situation into account, but simultaneously disconnect the live wire pin, neutral wire pin, and grounding pin of the electrical appliance plug, resulting in the residual voltage measured at the grounding electrode generally being higher than the specified value of the standard at 1 second, making it difficult to simulate the real application scenario. Summary of the Invention

[0006] The main purpose of the present invention is to provide a method for testing residual voltage, which more accurately measures the residual voltage of the electrical appliance after power-off by simulating the real plug unplugging process, that is, first disconnecting the live wire and the neutral wire, and then delaying the disconnection of the grounding pin. This method can not only ensure the accuracy of the test results but also improve the reliability of the safety performance evaluation of electrical equipment.

[0007] To achieve the above object, the technical solution adopted by the present invention is as follows:

[0008] A method for testing residual voltage, characterized by comprising the following steps:

[0009] S1: Ensure that the residual voltage tester is correctly connected to the power supply and is in an available state;

[0010] S2: Set the voltage range of the tester according to the operating voltage requirements of the electrical appliance to be tested;

[0011] S3: Connect the sample power terminal on the tester panel to the working power supply of the test equipment;

[0012] S4: Connect the power plug of the electrical appliance to be tested to the socket on the tester panel through a time-difference disconnector, and ensure that the test circuits of each pin of the power plug of the electrical appliance to be tested are correctly connected;

[0013] S5: Preset the test waiting time and the grounding pin lag disconnection time;

[0014] S6: Press the power-on button of the tester to connect the electrical appliance to be tested to the working power supply;

[0015] S7: Let the electrical appliance to be tested run for an appropriate period of time to ensure that it reaches a stable state;

[0016] S8: Press the measurement button of the tester, and the time-difference disconnector disconnects the working power supply and the grounding of the electrical appliance to be tested in sequence according to the grounding pin lag disconnection time preset in step S5;

[0017] S9: When the test waiting time set in step S5 is reached, immediately measure the power plug of the electrical appliance to be tested and check the residual voltage between each pin.

[0018] Furthermore, the time-difference disconnector described in step S4 includes a plug adapter and a control circuit. The housing of the plug adapter is made of an insulating material, and the inside is provided with a live wire socket, a neutral wire socket and a grounding socket. The control circuit includes a main control chip, a power-off control module, a grounding control module and a delay circuit.

[0019] Furthermore, the specific implementation steps of S8 are as follows:

[0020] S801: When the measurement button of the tester is pressed, the main control chip receives the power-off instruction from the main control unit of the tester and instructs the power-off control module to simultaneously cut off the power supply of the live wire and neutral wire sockets;

[0021] S802: The delay circuit starts timing and waits for a corresponding time according to the grounding pin disconnection lag time preset in the main control chip;

[0022] S803: When the delay time arrives, the delay control module sends a signal to the main control chip;

[0023] S804: After receiving the signal, the main control chip instructs the grounding control module to disconnect the grounding.

[0024] Furthermore, the differential time relay further includes a connection circuit for connecting each pin of the power socket of the electrical appliance under test to the test circuit of the tester, and the test circuit includes a voltage measurement module and a signal transmission module.

[0025] Furthermore, the specific implementation steps of S9 are as follows:

[0026] S901: After reaching the preset test waiting time, the tester immediately activates the voltage measurement module to measure the residual voltage between each pin;

[0027] S902: The voltage measurement module transmits the measured residual voltage data to the main control unit of the tester through the signal transmission module;

[0028] S903: After receiving the data, the main control unit processes and analyzes the data and displays the result on the human-machine interaction interface of the tester for the tester to read and record;

[0029] S904: The tester judges whether the electrical appliance under test meets the relevant safety standards or regulations according to the displayed residual voltage value. If the residual voltage exceeds the specified value, it indicates that the electrical appliance under test may have potential safety hazards.

[0030] Furthermore, the preset test waiting time in step S5 is 1 s.

[0031] Furthermore, the preset lag time for disconnecting the grounding pin in step S5 is 3.40 ms - 7.00 ms.

[0032] Furthermore, the preset lag time for disconnecting the grounding pin in step S5 is 5.00 ms.

[0033] Compared with the prior art, the present invention has the following remarkable effects:

[0034] The present invention deeply considers the actual conditions of each pin in an electrical plug, and in view of the characteristic that the grounding pin is longer than the live wire and neutral wire pins, the test method for residual voltage is optimized. By simulating the actual plug unplugging process, that is, within a period of time after the live wire and neutral wire pins disconnect the working power supply, the grounding pin still remains grounded. After reaching the preset test waiting time, first disconnect the live wire and neutral wire, and then disconnect the grounding pin after a delay, which can more accurately evaluate the safety performance of the electrical appliance after power-off. The method adopted by the present invention not only improves the accuracy of the test results, but also enhances the reliability of the safety performance evaluation of electrical equipment, providing a solid guarantee for the safe use of electrical equipment. In addition, the residual voltage test method of the present invention is easy to operate and popularize, and has broad application potential. BRIEF DESCRIPTION OF THE DRAWINGS

[0035] In order to more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the following will briefly introduce the drawings required for the description of the embodiments or the prior art. Obviously, the following drawings are only some embodiments of the present invention. For those of ordinary skill in the art, without creative efforts, other drawings can be obtained based on these drawings.

[0036] Figure 1 It is a schematic flowchart of the residual voltage test method of the present invention;

[0037] Figure 2 It is a schematic flowchart of step S8 in the residual voltage test method of the present invention;

[0038] Figure 3 It is a schematic flowchart of step S9 in the residual voltage test method of the present invention; DETAILED DESCRIPTION OF THE EMBODIMENTS

[0039] In order to make the technical means, creative features, achieved purposes and functions of the present invention easy to understand, the present invention will be further described below in conjunction with specific embodiments.

[0040] In the description of the present invention, it should be noted that the terms "upper", "lower", "inner", "outer", "front end", "rear end", "both ends", "one end", "the other end", etc. indicate the orientation or position relationship based on the orientation or position relationship shown in the drawings. It is only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore should not be construed as a limitation of the present invention. In addition, the terms "first" and "second" are only used for descriptive purposes and cannot be construed as indicating or implying relative importance.

[0041] In the description of the present invention, it should be noted that unless otherwise clearly specified and defined, terms such as "installation", "provided with", "connection", etc. should be understood in a broad sense. For example, "connection" can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be directly connected or indirectly connected through an intermediate medium, and it can be the communication inside two components. For those of ordinary skill in the art, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0042] Figure 1 The first embodiment of the present invention is shown: a residual voltage test method, including the following steps:

[0043] S1: Ensure that the residual voltage tester is correctly connected to the power supply and is in an available state;

[0044] S2: Set the voltage range of the tester according to the operating voltage requirements of the electrical appliance to be tested;

[0045] S3: Connect the sample power terminal on the tester panel to the working power supply of the test equipment;

[0046] S4: Connect the power plug of the electrical appliance to be tested to the socket on the tester panel through a time-delay disconnector, and ensure that the test circuits of each pin of the power plug of the electrical appliance to be tested are correctly connected;

[0047] S5: Preset the test waiting time and the grounding pin lag disconnection time;

[0048] S6: Press the power-on button of the tester to connect the electrical appliance to be tested to the working power supply;

[0049] S7: Let the electrical appliance to be tested run for an appropriate period of time to ensure that it reaches a stable state;

[0050] S8: Press the measurement button of the tester, and the time-delay disconnector disconnects the working power supply and the grounding of the electrical appliance to be tested in sequence according to the grounding pin lag disconnection time preset in step S5;

[0051] S9: When the test waiting time preset in step S5 is reached, immediately measure the power plug of the electrical appliance to be tested and check the residual voltage between each pin.

[0052] In this embodiment, the recommended residual voltage tester is a general-purpose tester, such as the LSK-CY type tester of the Langsike brand. This tester complies with many domestic and foreign standards including GB7000, GB4706.1, GB9706.1, GB4793.1, and GB8898, and is applicable to the residual voltage testing of various electrical equipment such as household appliances, medical electrical equipment, and lamps. Its residual voltage detection range covers 0.1 to 199.9V, and the accuracy can reach ±1%, ensuring the accurate measurement of the residual voltage value and providing a solid guarantee for high-precision detection.

[0053] In this embodiment, the differential time relay described in step S4 includes a plug adapter and a control circuit. The housing of the plug adapter is made of insulating material, and the inside is provided with a live wire socket, a neutral wire socket, and a ground socket. The control circuit includes a main control chip, a power-off control module, a ground control module, and a delay circuit. The main control chip serves as the control center, responsible for receiving and processing instructions from the main control unit of the tester, and controlling the operation of the power-off control module and the ground control module according to the preset program. The power-off control module is responsible for simultaneously disconnecting the power supply of the live wire and neutral wire sockets after receiving the power-off instruction, ensuring that the tested electrical appliance is quickly powered off. The ground control module disconnects the ground socket according to the instruction of the main control chip after the timing of the delay circuit ends, simulating the real plug unplugging process. The delay circuit plays a role in accurately controlling the disconnection time of the ground socket, ensuring that the ground pin remains grounded for a period of time after the live wire and neutral wire pins are disconnected, so as to achieve a more accurate test effect.

[0054] Please refer to Figure 2 , specifically, the specific implementation steps of S8 are as follows:

[0055] S801: When the measurement button of the tester is pressed, the main control chip receives the power-off instruction from the main control unit of the tester and instructs the power-off control module to simultaneously disconnect the power supply of the live wire and neutral wire sockets;

[0056] S802: The delay circuit starts timing and waits for the corresponding time according to the preset lag time for the ground pin to disconnect in the main control chip;

[0057] S803: When the delay time arrives, the delay control module sends a signal to the main control chip;

[0058] S804: After receiving the signal, the main control chip instructs the ground control module to disconnect the ground.

[0059] During specific implementation, the differential time relay further includes a connection circuit, which is used to connect each pin of the power socket of the electrical appliance under test to the test circuit of the tester. The test circuit includes a voltage measurement module and a signal transmission module. Preferably, the voltage measurement module uses a high-precision voltage sensor, which can measure the residual voltage between each pin in real time and accurately. This sensor has a wide measurement range and high sensitivity, ensuring the accuracy and stability of the measurement. At the same time, the signal transmission module uses high-speed and reliable signal transmission technology to ensure that the measurement data can be quickly and accurately transmitted to the main control unit of the tester for subsequent processing and analysis.

[0060] Please refer to Figure 3 , specifically, the specific implementation steps of S9 are as follows:

[0061] S901: After reaching the preset test waiting time, the tester immediately activates the voltage measurement module to measure the residual voltage between each pin.

[0062] S902: The voltage measurement module transmits the measured residual voltage data to the main control unit of the tester through the signal transmission module.

[0063] S903: After receiving the data, the main control unit processes and analyzes the data and displays the results on the human-machine interface of the tester for the tester to read and record.

[0064] S904: The tester judges whether the electrical appliance under test meets the relevant safety standards or regulations according to the displayed residual voltage value. If the residual voltage exceeds the specified value, it indicates that there may be a safety hazard in the electrical appliance under test.

[0065] Preferably, the differential time relay further includes an indicator light module, which is used to display the working state of the socket, such as whether the power is on, whether the grounding pin is disconnected, etc. Under the control of the main control chip, the indicator light module can emit light of different colors or flash at different frequencies to indicate different working states, thus helping the tester more intuitively understand the test process.

[0066] The applicant found in the experiment that when using a standard plug for horizontal plugging and unplugging, the disconnection time of the grounding pin lags behind that of the live wire and neutral wire pins. The measured lag time data is shown in Table 1 below:

[0067] Serial number 1 2 3 4 5 6 Average value Lag time / ms 6.48 7.00 6.56 6.82 6.62 5.68 6.53

[0068] Table 1

[0069] When using a standard plug for vertical plugging and unplugging, the disconnection time of the grounding pin lags behind that of the live wire and neutral wire pins. The measured lag time data is shown in Table 2 below:

[0070] Serial number 1 2 3 4 5 6 Average value Lag time / ms 4.82 3.98 4.32 3.64 3.82 3.40 3.99

[0071] Table II

[0072] Test example:

[0073] Perform a residual voltage test on a certain wall-mounted variable-frequency air conditioner in accordance with Clause 22.5 of the GB 4706.1-2005 standard to measure the residual voltage between the grounding pin and the neutral pin;

[0074] At the peak, simultaneously disconnect the live pin, the neutral pin, and the grounding pin. The voltage between the grounding pin and the neutral pin measured at 1 second is 152V;

[0075] At the peak, simultaneously disconnect the live pin and the neutral pin, and disconnect the grounding pin with a 5 ms delay. The voltage between the grounding pin and the neutral pin measured at 1 second is 7V.

[0076] In summary, the present invention deeply considers the actual conditions of each pin in the electrical plug, and optimizes the test method for the residual voltage in view of the characteristic that the grounding pin is longer than the live pin and the neutral pin. By simulating the actual plug unplugging process, that is, within a period of time after the live pin and the neutral pin are disconnected from the working power supply, the grounding pin still maintains the grounding state. After reaching the preset test waiting time, first disconnect the live pin and the neutral pin, and then disconnect the grounding pin after a delay, which can more accurately evaluate the safety performance of the electrical appliance after power-off. The method adopted by the present invention not only improves the accuracy of the test results, but also enhances the reliability of the safety performance evaluation of electrical equipment, providing a solid guarantee for the safe use of electrical equipment. In addition, the residual voltage test method of the present invention is simple to operate and easy to popularize, and has broad application potential.

[0077] The above shows and describes the basic principles, main features and advantages of the present invention. Those skilled in the art should understand that the present invention is not limited by the above embodiments. What is described in the above embodiments and the specification only illustrates the principle of the present invention. Without departing from the spirit and scope of the present invention, the present invention will have various changes and improvements, and these changes and improvements all fall within the scope of the present invention claimed. The scope of protection claimed by the present invention is defined by the appended claims and their equivalents.

Claims

1. A residual voltage testing method, characterized in that The following steps are involved: S1: Make sure the residual voltage tester is properly connected to the power supply and is in usable state; S2: Set the voltage level of the tester according to the operating voltage requirement of the electrical appliance under test; S3: Connect the sample power terminal on the tester panel to the working power supply of the test equipment; S4: Connect the power plug of the tested electrical appliance to the socket on the tester panel through the differential time breaker, and ensure that the test circuits of each pin of the power plug of the tested electrical appliance are correctly connected; S5: preset test waiting time and ground pin disconnection delay time; S6: Press the power button of the tester to connect the tested electrical appliance to the working power supply; S7: Allow the appliance under test to run for an appropriate period of time to ensure that it reaches a stable state; S8: Press the measuring button of the tester, and the differential time breaker disconnects the working power supply and grounding of the tested electrical appliance in turn according to the delayed disconnection time of the grounding pin preset in step S5; S9: When the test waiting time preset in step S5 is reached, the power plug of the tested electrical appliance is immediately measured to check the residual voltage between the pins.

2. The residual voltage testing method according to claim 1, characterized in that: The differential time breaker described in step S4 includes a plug adapter and a control circuit. The shell of the plug adapter is made of insulating material, and is provided with a live wire socket, a neutral wire socket and a grounding socket inside. The control circuit includes a main control chip, a power-off control module, a grounding control module and a delay circuit.

3. The residual voltage testing method according to claim 2, characterized in that: The specific implementation steps of S8 are: S801: When the measuring button of the tester is pressed, the main control chip receives the power-off instruction from the main control unit of the tester and instructs the power-off control module to simultaneously disconnect the working power supply of the live wire and neutral wire sockets; S802: The delay circuit starts timing and waits for a corresponding time according to the ground pin disconnection lag time preset in the main control chip; S803: When the delay time is reached, the delay control module sends a signal to the main control chip; S804: After receiving the signal, the main control chip instructs the grounding control module to disconnect the grounding.

4. The residual voltage testing method according to claim 2 or 3, characterized in that: The differential time breaker also includes a connection circuit, which is used to connect each pin of the power socket of the tested appliance with the test circuit of the tester. The test circuit includes a voltage measurement module and a signal transmission module.

5. The residual voltage testing method according to claim 4, characterized in that: The specific implementation steps of S9 are: S901: After reaching the preset test waiting time, the tester immediately starts the voltage measurement module to measure the residual voltage between each pin; S902: The voltage measurement module transmits the measured residual voltage data to the main control unit of the tester through the signal transmission module; S903: After receiving the data, the main control unit processes and analyzes the data and displays the results on the human-computer interaction interface of the tester so that the tester can read and record them; S904: The tester determines whether the tested electrical appliance complies with relevant safety standards or regulations based on the displayed residual voltage value. If the residual voltage exceeds the specified value, it indicates that the tested electrical appliance may have safety hazards.

6. The residual voltage testing method according to claim 1 or 5, characterized in that: The test waiting time preset in step S5 is 1 s.

7. The residual voltage testing method according to claim 5, characterized in that: The ground pin disconnection hysteresis time preset in step S5 is 3.40 ms-7.00 ms.

8. The residual voltage testing method according to claim 6, characterized in that: The ground pin disconnection hysteresis time preset in step S5 is 5.00 ms.

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