A power capacitor residual voltage measuring device

Abstract

This invention discloses a residual voltage measuring device for power capacitors. The device includes: three miniature high-voltage switches, a high-voltage divider resistor circuit, a voltmeter, a main control board, and a remote control terminal. The high-voltage divider resistor circuit includes four high-voltage resistors, one low-voltage resistor, and a zinc oxide protective resistor. When the first and second miniature high-voltage switches are closed, they are used to measure the residual voltage of the test capacitor. When the third miniature high-voltage switch is open, the residual voltage measurement mode is a high-voltage measurement mode; when the third miniature high-voltage switch is closed, it is a low-voltage measurement mode. The voltmeter is connected across the low-voltage resistor. The main control board controls the closing and opening of the third miniature high-voltage switch, initiates the measurement, and starts timing. The residual voltage value and timing data are sent to the remote control terminal. The remote control terminal is used to receive the residual voltage value and timing data.

Description

Technical Field

[0001] This invention relates to the field of residual voltage measurement technology for power capacitors, and more specifically, to a device for measuring residual voltage of power capacitors. Background Technology

[0002] Power capacitors are crucial devices in power systems for power regulation and energy storage, and are widely used across all voltage levels. Power capacitors can store and carry enormous amounts of energy, so even after being taken out of service or completing a withstand voltage test, they retain a high voltage. Capacitor manufacturers typically incorporate a discharge resistor inside the capacitor to reduce the voltage to a sufficiently low safe range within minutes after power is disconnected. Measuring the residual voltage after self-discharge following a withstand voltage test verifies the safety and effectiveness of the capacitor's discharge mechanism.

[0003] However, if the capacitor's discharge circuit fails, the capacitor will remain at a dangerously high voltage, posing a potential safety threat to test personnel measuring the residual voltage.

[0004] Therefore, a technology is needed to enable the safe measurement of residual voltage in power capacitors. Summary of the Invention

[0005] The present invention provides a device for measuring the residual voltage of a power capacitor to solve the problem of how to safely measure the residual voltage of a power capacitor.

[0006] To address the aforementioned problems, this invention provides a residual voltage measuring device for power capacitors. The device comprises: three miniature high-voltage switches, a high-voltage divider resistor circuit, a voltmeter, a main control board, and a remote control terminal, wherein:

[0007] The high-voltage divider resistor circuit includes four high-voltage resistors, one low-voltage resistor, and a zinc oxide protective resistor. The first high-voltage resistor, the second high-voltage resistor, the third high-voltage resistor, the fourth high-voltage resistor, and the low-voltage resistor are connected in series. The zinc oxide protective resistor is connected in parallel across the voltmeter resistor.

[0008] The first terminal of the first miniature high-voltage switch and the second terminal of the second miniature high-voltage switch are respectively connected to the first terminal and the second terminal of the test capacitor; the second terminal of the first miniature high-voltage switch is connected to the first terminal of the first high-voltage divider resistor, and the first terminal of the second miniature high-voltage switch is connected to the second terminal of the low-voltage resistor.

[0009] The third miniature high-voltage switch is connected to the first terminal of the first high-voltage divider resistor and the second terminal of the third high-voltage resistor respectively; when the first miniature high-voltage switch and the second miniature high-voltage switch are closed, they are used to measure the residual voltage of the test sample capacitor; when the third miniature high-voltage switch is open, the residual voltage measurement mode is the high-level voltage measurement mode; when the third miniature high-voltage switch is closed, the residual voltage measurement mode is the low-level voltage measurement mode.

[0010] A voltmeter is connected across the low-voltage resistor;

[0011] The main control board is used to control the closing and opening of the three small high-voltage switches, start the measurement and complete the timing of the test process; it is used to read the measured voltage value of the voltmeter in real time through the RS232 interface, and obtain the residual voltage value of the test sample capacitor based on the measured voltage value and the voltage division ratio corresponding to the residual voltage measurement mode; it is used to send the obtained residual voltage value and timing data to the remote control terminal through the RS232 communication interface.

[0012] A remote control terminal is used to receive residual voltage values ​​and timing data, and to display the residual voltage values ​​and timing data.

[0013] Preferably, the DC breakdown voltage between the high-voltage contacts of the miniature high-voltage switch is not less than 100kV. The miniature high-voltage switch includes a control coil for closing and opening, and the voltage of the control coil is DC220V. This voltage is switched by a low-voltage relay, which is controlled by a 12V DC voltage. The main control board controls the voltage of the control coil of the miniature high-voltage switch to open and close the high-voltage contacts of the miniature high-voltage switch.

[0014] Preferably, the cavity of the miniature high-voltage switch contact is filled with insulating oil, the breakdown voltage of which is greater than 30kV at a 2.5mm spacing, and the maximum withstand voltage between the contacts is not less than 50kV AC or 100kV DC. The contact electrodes are short-circuited by a copper rod. When the miniature high-voltage switch is in the open state, the electromagnet is attracted by the permanent magnet at the bottom, and the two electrodes of the miniature high-voltage switch are completely insulated. When the closing coil of the miniature high-voltage switch is connected to a DC220V power supply, the electromagnet repels the permanent magnet at the bottom and attracts the electromagnet at the top, and the miniature high-voltage switch reaches the closed position. At this time, the electromagnet is attracted to the permanent magnet at the top, and the PP insulating rod connected to the electromagnet pushes the copper rod to the first electrode, and the two electrodes of the miniature high-voltage switch are connected.

[0015] Preferably, the high-voltage resistor is a high-precision 30kV glass glaze resistor, and the withstand voltage of the four high-voltage resistors combined reaches over 90kV DC; the low-voltage resistor is a precision resistor with a withstand voltage of 500V; when the measured voltage is higher than 400V, the residual voltage measurement mode is adjusted to the high-level voltage measurement mode; when the measured voltage is lower than 400V, the residual voltage measurement mode is adjusted to the low-level voltage measurement mode; the main control board short-circuits the voltage divider resistor to close the third high-voltage switch, thereby reducing the measured voltage to 400V.

[0016] Preferably, the first, second, and third high-voltage resistors have a resistance of 33MΩ, a withstand voltage of 30kV, and a power of 10W; the fourth high-voltage resistor has a resistance of 200kΩ, a withstand voltage of 30kV, and a power of 10W; and the low-voltage resistor has a resistance of 200kΩ, a withstand voltage of 500V, and a power of 0.5W.

[0017] Preferably, the allowable input voltage of the voltmeter is AC200V, and the acquisition and refresh frequency is 0.1s per cycle.

[0018] Preferably, the main control board sends the residual voltage value and timing data to the remote control terminal through a Bluetooth chip operating in transparent transmission mode.

[0019] Preferably, the device includes a display unit for displaying the residual voltage value and timing data via a liquid crystal display.

[0020] Preferably, the measurement method of the device is as follows:

[0021] At a preset time, the first and second small high-voltage switches are turned on, and the voltage is collected and measured by a voltmeter.

[0022] When the measured voltage exceeds 400V, the measured voltage data is continuously acquired and timed in the high-level voltage measurement mode until the preset test time is reached.

[0023] When the measured voltage is below 400V, the third miniature high-voltage switch is turned on, and the high-voltage resistor is shorted to put the device in a low-range measurement mode to acquire the measured voltage data and time data. When the capacitor voltage continues to drop below 5V or the set minimum disconnection voltage value, the first, second, and third miniature high-voltage switches are disconnected.

[0024] Preferably, the main control board controls the device to initially measure in a high-voltage measurement mode. When the measured voltage drops to a low-voltage range of 400V and remains there for 3 seconds, the residual voltage measurement mode is set to a low-voltage range measurement mode, and the measurement and timing continue.

[0025] This invention provides a device for measuring the residual voltage of a power capacitor. The device includes: three miniature high-voltage switches, a high-voltage divider resistor circuit, a voltmeter, a main control board, and a remote control terminal. The high-voltage divider resistor circuit includes four high-voltage resistors, one low-voltage resistor, and a zinc oxide protective resistor. The first, second, third, and fourth high-voltage resistors and the low-voltage resistor are connected in series. The zinc oxide protective resistor is connected in parallel across the voltmeter resistor. The first terminal of the first miniature high-voltage switch and the second terminal of the second miniature high-voltage switch are respectively connected to the first and second terminals of the test capacitor. The second terminal of the first miniature high-voltage switch is connected to the first terminal of the first high-voltage divider resistor, and the first terminal of the second miniature high-voltage switch is connected to the second terminal of the low-voltage resistor. The third miniature high-voltage switch is connected to both the first terminal of the first high-voltage divider resistor and the third high-voltage resistor. The device comprises: a second end of a voltage-reducing resistor; a third small high-voltage switch used to measure the residual voltage of the test capacitor when the first and second small high-voltage switches are closed; a high-voltage measurement mode when the third small high-voltage switch is open; and a low-voltage measurement mode when the third small high-voltage switch is closed. A voltmeter is connected to both ends of the low-voltage resistor. A main control board is used to control the opening and closing of the third small high-voltage switch, initiate measurement, and time the measurement. A device for reading the measured voltage value from the voltmeter in real time via an RS232 interface, and obtaining the residual voltage value of the test capacitor based on the measured voltage value and the voltage division ratio corresponding to the residual voltage measurement mode. A device for sending the obtained residual voltage value and timing data to a remote control terminal via an RS232 communication interface. A remote control terminal is used to receive the residual voltage value and timing data, and display the residual voltage value and timing data. This invention provides a residual voltage measuring device for power capacitors, which automatically completes the measurement and timing of the capacitor's residual voltage upon activation by a wireless remote control switch, and can complete the self-discharge of the residual voltage within a specified time after the power capacitor withstand voltage test. The testing process of this invention is automated and contactless, keeping operators away from the high-pressure testing environment and ensuring personal safety. Attached Figure Description

[0026] Exemplary embodiments of the present invention can be more fully understood by referring to the following figures:

[0027] Figure 1 This is a structural diagram of a power capacitor residual voltage measuring device according to a preferred embodiment of the present invention;

[0028] Figure 2 A schematic diagram of the structural principle of a small high-voltage switch according to a preferred embodiment of the present invention; and

[0029] Figure 3 This is a typical experimental flowchart according to a preferred embodiment of the present invention. Detailed Implementation

[0030] Exemplary embodiments of the invention will now be described with reference to the accompanying drawings. However, the invention may be embodied in many different forms and is not limited to the embodiments described herein. These embodiments are provided to fully and completely disclose the invention and to fully convey its scope to those skilled in the art. The terminology used in the exemplary embodiments illustrated in the drawings is not intended to limit the invention. In the drawings, the same units / elements are referred to by the same reference numerals.

[0031] Unless otherwise stated, the terms used herein (including technical terms) have their common meaning as understood by one of ordinary skill in the art. Furthermore, it is understood that terms defined in commonly used dictionaries should be understood to have a meaning consistent with the context of their relevant field, and not to be interpreted as having an idealized or overly formal meaning.

[0032] Figure 1 This is a structural diagram of a residual voltage measuring device for power capacitors according to a preferred embodiment of the present invention. The present invention provides a safe residual voltage measuring device for power capacitors, relating to the inspection and testing of the self-discharge function of high-voltage power capacitors of 35kV and below. The residual voltage measuring device provided by the present invention is started wirelessly, automatically switches between voltage ranges, and automatically measures and times the voltage. The test process and test results are transmitted wirelessly to a remote control terminal for display and storage. The residual voltage measuring device can be installed across the power capacitor before the power capacitor test. During the withstand voltage test, a small high-voltage switch separates the measuring circuit from the capacitor. After the withstand voltage test is completed, the residual voltage measuring device, via a remote control terminal, remotely closes the small high-voltage switch and begins residual voltage measurement, calculating the discharge decay time of the residual voltage. The residual voltage measuring device has two ranges: a high-voltage range and a low-voltage range. The device switches to the selected voltage range according to the current voltage amplitude, ensuring accurate and reliable measurement data.

[0033] The residual voltage measuring device for power capacitors of the present invention is used to perform self-discharge function testing on power capacitors. This solves the safety risk of high-voltage electric shock that may exist when testers need to test the residual voltage of power capacitors at close range after the withstand voltage test to measure the discharge time and process of the residual voltage. The residual voltage testing process is simple, reliable and highly accurate. The operator does not need to touch the power capacitor throughout the entire test, which ensures high safety.

[0034] This invention relates to a safe residual voltage measuring device for power capacitors, which mainly consists of a small high-voltage switch, a resistor voltage divider circuit, a voltage measuring meter, and a communication control module. When the test process is started, the device measures the voltage value across the power capacitor in real time and times it synchronously. The voltage and timing data are transmitted to a remote control terminal for display and storage in real time.

[0035] like Figure 1 As shown, this invention provides a residual voltage measuring device for power capacitors. The device includes: three small high-voltage switches, a high-voltage divider resistor circuit, a voltmeter, a main control board, and a remote control terminal, wherein:

[0036] The high-voltage divider resistor circuit includes four high-voltage resistors, one low-voltage resistor, and a zinc oxide protective resistor. The first high-voltage resistor, the second high-voltage resistor, the third high-voltage resistor, the fourth high-voltage resistor, and the low-voltage resistor are connected in series in sequence. The zinc oxide protective resistor is connected in parallel across the two ends of the voltmeter resistor.

[0037] The first terminal of the first miniature high-voltage switch and the second terminal of the second miniature high-voltage switch are respectively connected to the first terminal and the second terminal of the test capacitor; the second terminal of the first miniature high-voltage switch is connected to the first terminal of the first high-voltage divider resistor, and the first terminal of the second miniature high-voltage switch is connected to the second terminal of the low-voltage resistor.

[0038] The third miniature high-voltage switch is connected to the first end of the first high-voltage divider resistor and the second end of the third high-voltage resistor respectively; when the first miniature high-voltage switch and the second miniature high-voltage switch are closed, they are used to measure the residual voltage of the test sample capacitor; when the third miniature high-voltage switch is open, the residual voltage measurement mode is the high-level voltage measurement mode; when the third miniature high-voltage switch is closed, the residual voltage measurement mode is the low-level voltage measurement mode.

[0039] Preferably, the DC breakdown voltage of the contacts of the miniature high-voltage switch is not less than 100kV, the voltage of the control coil of the miniature high-voltage switch is DC220V, and this voltage is switched by a low-voltage relay, which is controlled by a 12V DC voltage; the control coil of the miniature high-voltage switch is controlled by the main control board to control the closing and opening of the miniature high-voltage switch.

[0040] Preferably, the cavity of the small high-voltage switch contact is filled with insulating oil, the breakdown voltage of which is greater than 30kV at a 2.5mm spacing, and the maximum withstand voltage between the contacts is not less than 50kV AC or 100kV DC. The contact electrodes are short-circuited by a copper rod. When the switch is in the open position, the electromagnet is attracted by the permanent magnet at the bottom, and the two electrodes of the small high-voltage switch are completely insulated. When the closing coil of the small high-voltage switch is connected to a DC220V power supply, the electromagnet repels the permanent magnet at the bottom and attracts the electromagnet at the top. The switch reaches the closed position, at which point the electromagnet is attracted to the permanent magnet at the top, and the PP insulating rod connected to the electromagnet pushes the copper rod to the first electrode, thus making the two electrodes of the small high-voltage switch conductive.

[0041] Preferably, the high-voltage resistor is a high-precision 30kV glass glaze resistor, and the withstand voltage of the four high-voltage resistors combined reaches over 90kV DC; the low-voltage resistor is a precision resistor with a withstand voltage of 500V; when the measured voltage is higher than 400V, the residual voltage measurement mode is adjusted to the high-level voltage measurement mode; when the measured voltage is lower than 400V, the residual voltage measurement mode is adjusted to the low-level voltage measurement mode; the main control board short-circuits the voltage divider resistor to close the third high-voltage switch, thereby reducing the measured voltage to 400V.

[0042] Preferably, the first, second, and third high-voltage resistors have a resistance of 33MΩ, a withstand voltage of 30kV, and a power of 10W; the fourth high-voltage resistor has a resistance of 200kΩ, a withstand voltage of 30kV, and a power of 10W; and the low-voltage resistor has a resistance of 200kΩ, a withstand voltage of 500V, and a power of 0.5W.

[0043] The miniature high-voltage switch of this invention has a direct DC breakdown voltage of not less than 100kV between its contacts. It includes closing and opening control coils, the coil voltage of which is controlled by a relay and is DC 220V. The control module of the measuring device controls the opening and closing of the high-voltage switch by switching the closing and opening coil voltages of the miniature high-voltage switch via an internal relay. This invention comprises three miniature high-voltage switches. Figure 1 As shown, electrodes 2 and 2 terminals of the capacitor and high-voltage divider resistor 2 are respectively installed. When the high-voltage switch at electrode 2 is closed, the device begins measuring the residual voltage of the power capacitor. When the high-voltage switch at both ends of the high-voltage divider resistor is open, the device is in a high-range voltage measurement mode. When the high-voltage switch is closed, the high-voltage resistor at the front end of the divider resistor is short-circuited, and the device is in a low-range measurement mode. The short-circuiting of the high-voltage switch by the divider resistor is controlled by remote control software. Closing is only allowed when the meter voltage is lower than the set voltage value. The software automatically protects against accidental switching of ranges.

[0044] The residual voltage measuring device for power capacitors of this invention comprises a resistive voltage divider circuit consisting of four high-voltage resistors, one low-voltage resistor, and a zinc oxide protective resistor. It can measure voltages ranging from 0-50kV DC. The high-voltage resistors are high-precision 30kV glass-glazed resistors, and the combined withstand voltage can reach over 90kV. The low-voltage resistor is a 500V precision resistor. When the voltage is higher than 400V, the device uses the high-voltage range. When the voltage is lower than 400V, the device automatically switches to the low-voltage range after voltage confirmation. The main control board short-circuits the voltage divider resistors to close the high-voltage switch 3, reducing the measuring range to 400V. The zinc oxide protective resistor is connected across the sampling resistor. Under normal operating conditions, it is in a high-resistance mode and does not operate. When the device experiences a current switching error or the input voltage exceeds the maximum allowable value, the resistor conducts, limiting the voltage of the input voltmeter, thereby protecting downstream instruments from overvoltage damage.

[0045] A voltmeter is connected across the low-voltage resistor.

[0046] Preferably, the allowable input voltage of the voltmeter is AC200V, and the acquisition and refresh frequency is once every 0.1s.

[0047] The residual voltage measuring device for power capacitors of this invention uses a high-precision digital voltmeter with serial communication capabilities. The voltmeter's allowable input voltage is AC200V, and its acquisition and refresh frequency is once every 0.1 seconds. When the residual voltage measurement function is activated, the device's control board reads the voltage from the meter in real time via an RS232 port. Combining this with the currently selected voltage divider resistor range, the device multiplies the meter voltage V by the current voltage division ratio K to obtain the voltage value at terminal 2 of the power capacitor. The measured high-voltage value is then displayed on an LCD screen and transmitted wirelessly to a remote control terminal for display and recording via a Bluetooth wireless transmission port.

[0048] The main control board is used to control the closing and opening of three small high-voltage switches, start the measurement and complete the timing of the test process; it is used to read the measured voltage value of the voltmeter in real time through the RS232 interface, and obtain the residual voltage value of the test sample capacitor based on the measured voltage value and the voltage division ratio corresponding to the residual voltage measurement mode; it is used to send the obtained residual voltage value and timing data to the remote control terminal through the RS232 communication interface.

[0049] Preferably, the main control board sends the residual voltage value and timing data to the remote control terminal through a Bluetooth chip operating in transparent transmission mode.

[0050] The control board of the residual voltage measuring device for power capacitors of this invention integrates an ARM processor LPC2148, which has two RS232 communication interfaces. Serial port 1 communicates with the voltmeter via RS232 level conversion using the MAX3232 RS232 chip, reading the voltage value from the voltmeter in real time. The communication control board of this invention communicates with a Bluetooth chip via serial port 2, and transmits data and commands to a remote control terminal through the Bluetooth chip in pass-through mode. The control board receives commands from the control terminal, starts the test and begins timing, transmitting the real-time measured voltmeter data and timing data to the control terminal. Initially, the measurement is at the high voltage setting. After the voltage drops to the low voltage setting and remains there for 3 seconds, the setting switch is switched to the low voltage setting, and measurement and timing continue.

[0051] A remote control terminal is used to receive and display residual voltage and timing data.

[0052] Preferably, the device includes a display unit for displaying the residual voltage value and timing data via a liquid crystal display.

[0053] The residual voltage measuring device for power capacitors of the present invention has an LCD display screen on its main body. The real-time reading of the voltmeter is simultaneously displayed on the LCD of the main body and the LCD of the remote control terminal. The remote control terminal of the present invention is a handheld terminal with Bluetooth communication function, LCD display and control buttons. The residual voltage measuring device can be operated on the control terminal, and the voltage reading of the residual voltage measuring device and the status of each high voltage switch can be displayed in real time.

[0054] Preferably, the measurement method of the device is as follows:

[0055] At a preset time, the first and second small high-voltage switches are turned on, and the voltage is collected and measured by a voltmeter.

[0056] When the measured voltage exceeds 400V, the measured voltage data is continuously acquired and timed in the high-level voltage measurement mode until the preset test time is reached.

[0057] When the measured voltage is below 400V, the third miniature high-voltage switch is turned on, and the high-voltage resistor is shorted to put the device in the low-range measurement mode to acquire the measured voltage data and time data. When the capacitor voltage continues to drop below 5V or the set minimum disconnection voltage value, the first, second, and third miniature high-voltage switches are disconnected.

[0058] Preferably, the main control board and control device initially measure in the high voltage measurement mode. When the measured voltage drops to the low voltage range of 400V and remains there for 3 seconds, the residual voltage measurement mode is set to the low voltage range measurement mode, and the measurement and timing continue.

[0059] This invention relates to a residual voltage measuring device for power capacitors. It is activated by a wireless remote control switch and automatically completes the measurement and timing of the residual voltage of the capacitor. It detects whether the residual voltage of the power capacitor can self-discharge within a specified time after the withstand voltage test. The testing process is automated and contactless, and the operator is kept away from the high-voltage test environment, ensuring personal safety.

[0060] To ensure the safety of test personnel and to accurately measure the residual voltage on capacitors, this invention provides a device that can be remotely started by a remote control and automatically completes the measurement of residual capacitance, allowing test personnel to stay away from dangerous high-voltage environments.

[0061] The schematic diagram of the residual voltage testing device for power capacitors of the present invention is as follows: Figure 1 As shown, the device mainly consists of a small high-voltage switch, a high-voltage divider resistor, a voltmeter, a main control board, and a wireless remote control terminal.

[0062] The schematic diagram of the miniature high-voltage switch of this invention is as follows: Figure 2 As shown, the cavity between the switch contacts is filled with insulating oil, and the maximum withstand voltage between the contacts is not less than 50kV AC and 100kV DC. The contact electrodes are short-circuited by a copper rod. When the switch is in the open state, the electromagnet is attracted by the permanent magnet at the bottom, and the copper rod is pulled to the position shown in contact 2 through the insulated PP rod. At this time, the two electrodes of the small high-voltage switch are completely insulated. When the closing coil of the small high-voltage switch is connected to a DC 220V power supply, the electromagnet repels the permanent magnet at the bottom and attracts the electromagnet at the top. The switch reaches the closed position, and the electromagnet is attracted to the permanent magnet at the top. The PP insulated rod connected to the electromagnet pushes the copper rod to electrode 1. At this time, electrode 1 and electrode 2 are short-circuited, and the two electrodes of the switch are conductive.

[0063] The high-voltage divider circuit of this invention consists of four high-voltage glass glaze resistors R1-R4, one ordinary resistor R5, and a zinc oxide resistor protection sheet. Under normal operating conditions, the voltage division ratio K1 = (R1 + R2 + R3 + R4 + R5) / R5. The high voltage from the power capacitor, after being divided by the high-voltage glass glaze resistors and the ordinary resistor, enters the voltmeter with an amplitude not exceeding 200V. The processor on the control board continuously monitors the voltmeter voltage during the measurement process. When in the high-voltage range, and the voltmeter voltage is below 400V for 3 consecutive seconds, the device activates the high-voltage switch across the voltage divider resistors, placing the voltage divider circuit in the 400V range. After the range switching is completed, the control board adjusts the proportional coefficient of the voltage divider to K2, with a value of (R4 + R5) / R5, and the measuring device enters the low-voltage measurement range. A zinc oxide resistance element is connected in parallel across the voltage divider. When an incorrect range switch occurs or an excessively high voltage appears at the voltage divider, the zinc oxide resistance element activates, limiting the voltage entering the voltmeter and protecting downstream instruments to prevent overvoltage damage. High-voltage resistors R1-R3 have a resistance of 33MΩ, a withstand voltage of 30kV, and a power rating of 10W. Resistor R4 has a resistance of 200kΩ, a withstand voltage of 30kV, and a power rating of 10W. Resistor R5 has a resistance of 200kΩ, a withstand voltage of 500V, and a power rating of 0.5W.

[0064] The voltmeter of this invention is connected in parallel across the low-voltage resistor R5 to measure the voltage drop across R5. This voltage drop is then multiplied by the current voltage divider proportional gain K1 to obtain the measured high-voltage value, which is displayed and transmitted to the remote control terminal. When the control board activates the high-voltage switch, the voltage divider proportional gain is adjusted to K2. The control board then displays the value obtained by multiplying K2 by V on the LCD screen and transmits it to the remote control terminal, where V is the current voltmeter reading. The voltmeter has an RS232 communication interface with a refresh rate of 0.1 seconds. The control board reads the current voltmeter reading in real time via the RS232 interface. This value, multiplied by the current voltage divider proportional gain, is the residual voltage value of the power capacitor.

[0065] The control board of this invention consists of a main controller, I / O output circuits, and an RS232 communication module. The main controller is an ARM chip, specifically an LPC2148. The main controller controls the onboard relays via I / O ports after amplification, thereby controlling the closing and opening of a small high-voltage switch. The LPC2148 controller has two full-duplex RS232 communication interfaces. Serial port 1, after level conversion by a MAX3232, connects to a voltmeter to read real-time voltage values. Serial port 2 directly connects to a Bluetooth chip in transparent mode via TTL level, enabling communication with a remote control module.

[0066] The wireless remote control terminal of this invention is a handheld display terminal with Bluetooth communication function, and its schematic diagram is as follows. Figure 1 As shown, the internal main controller chip is an LPC2148. Communication between the remote control terminal and the residual voltage measuring device is achieved through the main control chip and the onboard Bluetooth pass-through module. The remote control terminal is equipped with start and stop buttons. When the start measurement is clicked, the main controller of the remote control terminal transmits the test start command to the residual voltage measuring device via the Bluetooth communication module and receives real-time test data from the residual voltage measuring device, including the current measured high voltage value, test timing, and high voltage switch status.

[0067] The residual voltage measuring device for power capacitors of the present invention, when performing a residual voltage measurement test on a power capacitor, typically operates as follows: Figure 3 As shown.

[0068] The detailed experimental procedure can be described as follows:

[0069] After the withstand voltage test is ready, connect the capacitor electrode to the measuring terminal of the device;

[0070] After ensuring the connection is correct, perform a withstand voltage test first. After the withstand voltage test is completed, set the parameters through the wireless control terminal and start the test.

[0071] The residual voltage measuring device continuously measures the high voltage value across the power capacitor and determines whether a range switch is needed.

[0072] If the voltage drops to a level that requires switching gears, the voltage measurement gear will be set to 400V.

[0073] Continue measuring until the set test time;

[0074] Once the measured voltage of the power capacitor drops to the set minimum voltage threshold, the high-voltage switch is disconnected, the test is completed, and the measured voltage and time data are displayed.

[0075] The residual voltage testing device for power capacitors provided by this invention can be directly connected and installed across the two ends of the power capacitor before the withstand voltage test, eliminating the need for wiring while the power capacitor is energized. During the test, this invention allows remote control acquisition of voltage changes during the discharge process of the power capacitor. When starting the test, the operator does not need to be near the power capacitor, ensuring greater safety by keeping away from high voltage. The internal high-voltage measurement of this invention has two ranges, allowing direct switching of the high-voltage divider circuit, resulting in a wider range of measurement voltages and greater accuracy and reliability.

[0076] Those skilled in the art will understand that embodiments of the present invention can be provided as methods, systems, or computer program products. Therefore, the present invention can take the form of a completely hardware embodiment, a completely software embodiment, or an embodiment combining software and hardware aspects. Furthermore, the present invention can take the form of a computer program product implemented on one or more computer-usable storage media (including but not limited to disk storage, CD-ROM, optical storage, etc.) containing computer-usable program code. The solutions in the embodiments of the present invention can be implemented using various computer languages, such as the object-oriented programming language Java and the interpreted scripting language JavaScript.

[0077] This invention is described with reference to flowchart illustrations and / or block diagrams of methods, apparatus (systems), and computer program products according to embodiments of the invention. It will be understood that each block of the flowchart illustrations and / or block diagrams, and combinations of blocks in the flowchart illustrations and / or block diagrams, can be implemented by computer program instructions. These computer program instructions can be provided to a processor of a general-purpose computer, special-purpose computer, embedded processor, or other programmable data processing apparatus to produce a machine, such that the instructions, which execute via the processor of the computer or other programmable data processing apparatus, generate instructions for implementing the flowchart illustrations and / or block diagrams. Figure 1 One or more processes and / or boxes Figure 1 A device that provides the functions specified in one or more boxes.

[0078] These computer program instructions may also be stored in a computer-readable storage medium that can direct a computer or other programmable data processing device to function in a particular manner, such that the instructions stored in the computer-readable storage medium produce an article of manufacture including instruction means, which are implemented in a process Figure 1 One or more processes and / or boxes Figure 1 The function specified in one or more boxes.

[0079] These computer program instructions may also be loaded onto a computer or other programmable data processing equipment to cause a series of operational steps to be performed on the computer or other programmable equipment to produce a computer-implemented process, thereby providing instructions that execute on the computer or other programmable equipment for implementing the process. Figure 1 One or more processes and / or boxes Figure 1 The steps of the function specified in one or more boxes.

[0080] Although preferred embodiments of the invention have been described, those skilled in the art, upon learning the basic inventive concept, can make other changes and modifications to these embodiments. Therefore, the appended claims are intended to be interpreted as including both the preferred embodiments and all changes and modifications falling within the scope of the invention.

[0081] Obviously, those skilled in the art can make various modifications and variations to this invention without departing from its spirit and scope. Therefore, if these modifications and variations fall within the scope of the claims of this invention and their equivalents, this invention also intends to include these modifications and variations.

[0082] The invention has been described with reference to a few embodiments. However, as will be known to those skilled in the art, and as defined in the appended claims, other embodiments besides those disclosed above fall equivalently within the scope of the invention.

[0083] Generally, all terms used in the claims are to be interpreted according to their ordinary meaning in the art, unless otherwise expressly defined herein. All references to “a / the / the [device, component, etc.]” ​​are openly interpreted as at least one instance of said device, component, etc., unless otherwise expressly stated. The steps of any method disclosed herein need not be performed in the exact order disclosed unless explicitly stated otherwise.

Claims

1. A device for measuring the residual voltage of a power capacitor, the device comprising: Three small high-voltage switches, a high-voltage divider resistor circuit, a voltmeter, a main control board, and a remote control terminal, including: The high-voltage divider resistor circuit includes four high-voltage resistors, one low-voltage resistor, and a zinc oxide protective resistor. The first high-voltage resistor, the second high-voltage resistor, the third high-voltage resistor, the fourth high-voltage resistor, and the low-voltage resistor are connected in series. The zinc oxide protective resistor is connected in parallel across the voltmeter resistor. The first terminal of the first miniature high-voltage switch and the second terminal of the second miniature high-voltage switch are respectively connected to the first terminal and the second terminal of the test capacitor; the second terminal of the first miniature high-voltage switch is connected to the first terminal of the first high-voltage divider resistor, and the first terminal of the second miniature high-voltage switch is connected to the second terminal of the low-voltage resistor. The third miniature high-voltage switch is connected to the first terminal of the first high-voltage divider resistor and the second terminal of the third high-voltage resistor respectively; when the first miniature high-voltage switch and the second miniature high-voltage switch are closed, they are used to measure the residual voltage of the test sample capacitor; when the third miniature high-voltage switch is open, the residual voltage measurement mode is the high-level voltage measurement mode; when the third miniature high-voltage switch is closed, the residual voltage measurement mode is the low-level voltage measurement mode. A voltmeter is connected across the low-voltage resistor; The main control board is used to control the closing and opening of the three small high-voltage switches, start the measurement and complete the timing of the test process; it is used to read the measured voltage value of the voltmeter in real time through the RS232 interface, and obtain the residual voltage value of the test sample capacitor based on the measured voltage value and the voltage division ratio corresponding to the residual voltage measurement mode; it is used to send the obtained residual voltage value and timing data to the remote control terminal through the RS232 communication interface. A remote control terminal is used to receive residual voltage values ​​and timing data, and to display the residual voltage values ​​and timing data.

2. The device according to claim 1, wherein the DC breakdown voltage of the contacts of the miniature high-voltage switch is not less than 100kV, the miniature high-voltage switch includes a control coil for closing and opening, the voltage of the control coil is DC220V, which is switched by a low-voltage relay, and the low-voltage relay is controlled by a 12V DC voltage; the main control board controls the voltage of the control coil of the miniature high-voltage switch to open and close the high-voltage contacts of the miniature high-voltage switch.

3. The device according to claim 1, wherein the cavity of the small high-voltage switch contact is filled with insulating oil, the breakdown voltage of the insulating oil at a 2.5mm spacing is greater than 30kV, and the maximum withstand voltage between the contacts is not less than 50kV AC or 100kV DC; the contact electrodes are short-circuited by a copper rod. When the small high-voltage switch is in the open state, the electromagnet is attracted by the permanent magnet at the bottom, and the two electrodes of the small high-voltage switch are completely insulated; when the closing coil of the small high-voltage switch is connected to a DC220V power supply, the electromagnet repels the permanent magnet at the bottom and attracts the electromagnet at the top, and the small high-voltage switch reaches the closed position. At this time, the electromagnet is attracted to the permanent magnet at the top, and the PP insulating rod connected to the electromagnet pushes the copper rod to the first electrode, and the two electrodes of the small high-voltage switch are connected.

4. The device according to claim 1, wherein the high-voltage resistor is a high-precision 30kV glass glaze resistor, and the withstand voltage of the four high-voltage resistors combined reaches DC 90kV or higher; the low-voltage resistor is a precision resistor with a withstand voltage of 500V; when the measured voltage is higher than 400V, the residual voltage measurement mode is adjusted to the high-level voltage measurement mode; when the measured voltage is lower than 400V, the residual voltage measurement mode is adjusted to the low-level voltage measurement mode; the main control board short-circuits the voltage divider resistor to close the third high-voltage switch, thereby reducing the measured voltage to 400V.

5. The device according to claim 1, wherein the first high-voltage resistor, the second high-voltage resistor, and the third high-voltage resistor have a resistance of 33MΩ, a withstand voltage of 30kV, and a power of 10W; the fourth high-voltage resistor has a resistance of 200kΩ, a withstand voltage of 30kV, and a power of 10W; and the low-voltage resistor has a resistance of 200kΩ, a withstand voltage of 500V, and a power of 0.5W.

6. The device according to claim 1, wherein the allowable input voltage of the voltmeter is AC200V, and the acquisition and refresh frequency is 0.1s per cycle.

7. The device according to claim 1, wherein the main control board sends the residual voltage value and timing data to the remote control terminal via a Bluetooth chip operating in transparent transmission mode.

8. The apparatus according to claim 1, the apparatus comprising a display unit for displaying the residual voltage value and timing data via a liquid crystal.

9. The apparatus according to claim 1, wherein the measurement method of the apparatus is as follows: At a preset time, the first and second small high-voltage switches are turned on, and the voltage is collected and measured by a voltmeter. When the measured voltage exceeds 400V, the measured voltage data is continuously acquired and timed in the high-level voltage measurement mode until the preset test time is reached. When the measured voltage is below 400V, the third miniature high-voltage switch is turned on, and the high-voltage resistor is shorted to put the device in the low-range measurement mode to acquire the measured voltage data and time data. When the capacitor voltage continues to drop below 5V or the set minimum disconnection voltage value, the first, second, and third miniature high-voltage switches are disconnected.

10. The device according to claim 9, wherein the main control board controls the device to initially measure in a high-voltage measurement mode, and after the measured voltage drops to a low-voltage range of 400V and remains there for 3 seconds, sets the residual voltage measurement mode to a low-voltage range voltage measurement mode and continues measurement and timing.

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