A short-circuit closing dynamic stability design and simulation checking method for grounding switches

Abstract

The application discloses a short-circuit closing dynamic stability design and simulation checking method of a grounding switch, and calculates and simulates the dynamic stability of the whole short-circuit closing process of a multi-contact finger blade-type grounding switch based on the finite element simulation technology of an electromagnetic field, and combines the design parameters of the grounding switch, first, the key positions of the contact system in the short-circuit closing process of the multi-contact finger blade-type grounding switch are finely divided in the time domain, starting from the pre-breakdown position of the contact system of the blade-type grounding switch to the position where the multiple pairs of contact fingers completely cut in to form a stable electric contact surface; secondly, the time-domain matching of the short-circuit current is performed on the contact system based on the time-domain information and the position information in the short-circuit closing process of the grounding switch; finally, the finite element simulation analysis of the electromagnetic field is performed on the key positions of the contact system in the short-circuit closing process of the grounding switch, and thus the simulation analysis of the whole short-circuit closing process of the grounding switch is realized.

Description

Technical Field

[0001] This application relates to a method for designing and simulating the dynamic stability of a grounding switch during short-circuit closing, particularly a method for designing and simulating the dynamic stability of a multi-touch finger knife-switch grounding switch during short-circuit closing, which belongs to the field of grounding switch verification technology. Background Technology

[0002] Grounding switches are important electrical equipment in power systems. When repairing power system faults, the circuit must be reliably grounded to ensure the personal safety of maintenance personnel. For E1-class grounding switches that require frequent opening and closing operations, to prevent malfunctions caused by human error or equipment failure, the grounding switch must have the ability to close short-circuit currents under this operating condition.

[0003] When a grounding switch closes during a short-circuit current, the instantaneously induced electrodynamic force under the high short-circuit impulse current will severely test the grounding circuit of the grounding switch, potentially leading to severe deformation or breakage of circuit structural components, generating a breakdown arc, and causing contact erosion or welding. The moving and stationary contact structure of the grounding switch is the weakest link in the grounding circuit system, especially for large-capacity grounding switches with multi-finger knife-switch designs, where the peak current withstand capability of the contact structure is even greater. Therefore, dynamic stability under short-circuit peak current is crucial to ensuring the reliability and stability of the grounding switch.

[0004] During the dynamic process of current-carrying closing of a high-capacity grounding switch with a multi-finger knife switch design, the relative positions of the moving and stationary contacts and their contact positions can be roughly divided into three stages: the arc pre-breakdown stage, the single-pair contact stage, and the multi-pair contact stage.

[0005] (1) The arc pre-breakdown stage is the process in which a breakdown arc is generated at both ends of the moving and stationary contacts when the relative distance between the moving and stationary contacts decreases to the threshold of the arc pre-breakdown distance. During this stage, the breakdown arc generates a circuit electrodynamic force that acts on the main circuit structure of the grounding switch, making the combined stress situation of the moving and stationary contacts of the grounding switch complex. Under the influence of the complex electromagnetic field and the randomness of the breakdown arc, it is difficult to accurately calculate the stress situation of the moving contact of the grounding switch in the pre-breakdown stage using theoretical formulas.

[0006] (2) The single-pair contact stage is the process from the moment the moving contact of the grounding switch makes contact with the stationary contact until the single pair of contact fingers are fully engaged and form a stable sliding contact surface with the stationary contact. During this stage, due to the influence of many parameters such as contact overtravel, engagement angle, and closing speed, the moving and stationary contacts will collide and bounce after contact, triggering arc reignition. At the same time, due to the changes in the relative position of the moving and stationary contacts and the short-circuit current, the magnitude and direction of the electrodynamic force generated between the moving and stationary contacts also change. This stage requires assessing whether the contact preload generated by the contact overtravel can withstand the combined effect of the electrodynamic repulsion force generated between the moving and stationary contact surfaces, as well as the electrodynamic force generated by arc reignition and the phase-to-phase circuit, which determines whether the single pair of contact fingers and the stationary contact can form a stable sliding contact surface.

[0007] (3) The multi-pair contact stage is the process from the contact of the second pair of moving fingers with the stationary contact until all moving fingers form a stable static contact surface with the stationary contact. In this stage, the dynamic process when the second pair of moving fingers cuts in is similar to that when the first pair of fingers cuts in, but since the moving and stationary contacts of the first pair of fingers form a stable sliding contact surface, no arc will be generated in this process. During the multi-pair contact stage, the short-circuit current of the grounding switch is about to reach or has already reached the peak value of the short-circuit current. The electric repulsion force between the moving and stationary contacts and the interphase electric force are relatively large in this stage, which puts forward higher requirements for the short-circuit current withstand capability of the contact system.

[0008] In summary, the simulation of the short-circuit closing process of a multi-touch knife-type grounding switch requires comprehensive calculation and verification of the force conditions of the moving contacts in three key states to ensure the dynamic stability of the grounding switch throughout the short-circuit closing process.

[0009] Electromagnetic field finite element simulation technology has been widely used in recent years in many aspects of electrical product structural design, product optimization, and performance verification. Taking the commonly used electromagnetic field finite element simulation software Ansoft-Maxwell as an example, it can solve the needs of electromagnetic field simulation in two-dimensional and three-dimensional models, and has many advantages such as accuracy, speed, and convenience. Electromagnetic field finite element simulation can provide visualized electromagnetic field calculation results, intuitively and accurately representing the distribution of electromagnetic fields in equipment and air gaps, and has a significant advantage in solving complex electromagnetic field calculations.

[0010] Currently, the design and verification of dynamic stability for large-capacity grounding switches using multi-contact knife-switch designs relies excessively on experimental methods. However, design flaws often lead to the failure of short-circuit closing tests, resulting in damage to prototypes and significant economic losses. Over-reliance on experimental methods for verifying structural dynamic stability hinders the continuous optimization of grounding switch structures and increases the research difficulty of dynamic stability design. Designing a practical and effective simulation method for the dynamic stability design and verification of grounding switches throughout the short-circuit closing process could greatly advance the technical research on the short-circuit closing capability of grounding switches.

[0011] Therefore, there is an urgent need for a method for dynamic stability design and simulation verification of multi-contact knife-type grounding switches during short-circuit closing, which can be used for simulation calculation and verification of the dynamic stability of the contact system during short-circuit closing of grounding switches. Summary of the Invention

[0012] The purpose of this application is to provide a method for performing stability calculation and simulation verification of the entire short-circuit closing process of a multi-touch finger knife-type grounding switch.

[0013] The specific technical solution is as follows: a method for designing and simulating the stability of grounding switch short-circuit closing, including the following steps:

[0014] Step 1: Obtain the design parameters of the grounding switch, including rated voltage Ue, peak short-circuit current Ich, rated frequency f, closing speed V1, cutting angle θ1, overtravel preload Fn, and moving and stationary contact overtravel H1.

[0015] Step 2: Calculate the arc pre-breakdown distance L1 using the empirical formula for the breakdown voltage of a uniform electric field gap and the rated voltage Ue.

[0016] Step 3: Taking the starting position of the arc pre-breakdown as the 0 point of the time domain axis, and combining the arc pre-breakdown distance L1 and the closing velocity V1, calculate the time it takes for the moving contact of the grounding switch to pass through the arc pre-breakdown distance, which is the arcing time T1.

[0017] Step 4: Using the parameters designed for the grounding switch, the cutting angle θ1 of the moving contact finger, the closing speed V1, and the overtravel H1 of the moving and stationary contacts, calculate the contact bounce time T2 and contact bounce height h1 of the first pair of contact fingers.

[0018] Step 5: Compare the contact bounce height h1 of the first pair of contact fingers with the expected arc breakdown distance L1. If the contact bounce height h1 is less than or equal to the expected arc breakdown distance L1, proceed to Step 6; if the contact bounce height h1 is greater than the expected arc breakdown distance L1, reduce the cutting angle θ1 of the grounding switch moving contact finger and return to Step 4 to recalculate.

[0019] Step 6: Accumulate the arcing time T1 of the grounding switch pre-breakdown stage and the contact bounce time T2 of the first pair of contact fingers in the time domain, which is the continuous arcing time T12.

[0020] Step 7: Use the short-circuit current time-domain matching method to match the short-circuit current value flowing through the grounding switch contact system in the time domain. Take the arc pre-breakdown start position as the 0 point of the time domain axis as the starting 0 point of the short-circuit current value in the grounding switch contact system for matching calculation, and calculate the maximum arcing current Id1 generated by the short-circuit current in time T12.

[0021] Step 8: Use electromagnetic field finite element simulation technology to calculate the instantaneous electrodynamic values ​​Ffx and Ffy of the contact where the arc root is located along the contact normal pressure direction fx and the switch closing direction fy when the arc current is Id1;

[0022] Step 9: Determine the magnitude of the instantaneous electromotive force Ffx of the contact where the arc root is located along the contact normal pressure direction fx and the magnitude of 1 / N times the overtravel preload Fn of the grounding switch contact, where N is 2 to 5; if the instantaneous electromotive force Ffx is less than or equal to 1 / N times the overtravel preload Fn of the grounding switch contact, proceed to Step 10; if the instantaneous electromotive force Ffx is greater than 1 / N times the overtravel preload Fn of the grounding switch contact, increase the overtravel H1 of the moving and stationary contacts of the grounding switch and return to Step 4 to recalculate;

[0023] Step 10: The arcing time T1 of the first phase of the grounding switch pre-breakdown stage, the contact bounce time T2 of the first pair of contact fingers, the continuous arcing time T12, and the instantaneous electrodynamic values ​​Ffx and Ffy of the contact where the arc root is located along the contact normal pressure direction fx and the switch closing direction fy;

[0024] Step 11: Calculate the time T3 when the first pair of moving contacts of the contact fingers cut in and the collision and bounce time T4 of the second pair of moving contacts of the contact fingers in the same time domain; and solve for the maximum short-circuit current Id2 before the second pair of moving contacts of the contact fingers cut in according to the short-circuit current time domain matching method provided in Step 7.

[0025] Step 12: Simulation calculations are performed to obtain the instantaneous electrodynamic values ​​Fdfx and Fdfy of the single contact finger along the contact normal force direction fx and the switch closing direction fy when the single moving contact is fully engaged;

[0026] Step 13: Calculate the time T5 when the moving contact of the second pair of contact fingers cuts in and the sliding contact time T6 of the multiple pairs of contact fingers, and calculate the total time Tz for the moving contact to cut in: T1 + ... + T6;

[0027] Step 14: Determine the magnitude of the total contact engagement time Tz and the half-time period of the rated current 1 / (2f); if the total contact engagement time Tz is less than or equal to the half-time period of the rated current 1 / (2f), calculate the instantaneous electrodynamic values ​​Fsfx and Fsfy of multiple pairs of contacts along the contact positive pressure direction fx and the switch closing direction fy under the short-circuit current peak value Ich; if the total contact engagement time Tz is greater than the half-time period of the rated current 1 / (2f), calculate the instantaneous electrodynamic values ​​Fdfx and Fdfy of a single contact along the contact positive pressure direction fx and the switch closing direction fy under the short-circuit current peak value Ich.

[0028] Step 15: Compare with the design requirements of the grounding switch, check whether the instantaneous electrodynamic force on the moving contact during the closing process of the grounding switch meets the design requirements, and give the verification conclusion.

[0029] The advantages of this application are:

[0030] 1) This application meticulously divides the key positions of the contact system during the short-circuit closing process of a multi-finger knife-type grounding switch in the time domain. From the pre-breakdown position of the knife-type grounding switch contact system to the point where multiple pairs of contact fingers are fully engaged to form a stable electrical contact surface, the key positions and key stages of the grounding switch closing process are clearly defined.

[0031] 2) Based on the time-domain and position information of the grounding switch during the short-circuit closing process, this application performs time-domain matching of the short-circuit current of the contact system and simultaneously calculates the closing position of the grounding switch and the short-circuit current value of the main circuit, thereby improving the accuracy of the excitation parameters of the electromagnetic field finite element simulation.

[0032] 3) In step six, the present invention accumulates the arcing time T1 of the grounding switch pre-breakdown stage and the contact bounce time T2 of the first pair of contact fingers in the time domain, which is the continuous arcing time T12. The short-circuit current value flowing through the grounding switch contact system obtained by matching the continuous arcing time T12 in the time domain is much larger than the short-circuit current value obtained by matching the arcing time T1 of the single pre-breakdown stage.

[0033] Therefore, the method provided in this application can improve the design margin of the grounding switch's arc withstand capability. Attached Figure Description

[0034] Figure 1 The simulation method flowchart provided in this application;

[0035] Figure 2 is a schematic diagram of the key positions of the contact system during the closing process of the grounding switch;

[0036] Figure 3 A schematic diagram of the design parameters for the grounding switch contacts;

[0037] Figure 4 This is a schematic diagram of a conductive bridge model;

[0038] Figure 5 This is a schematic diagram showing the location of the three-phase arc breakdown of the grounding switch.

[0039] Figure 6 Time-domain diagram of the short-circuit closing process of the grounding switch;

[0040] Figure 7 A schematic diagram of the electrodynamic force acting on the moving contact during the arc pre-breakdown stage;

[0041] Figure 8 This is a schematic diagram of the electrodynamic force acting on the moving contact during the contact phase of a single pair of contact fingers.

[0042] Figure 9 This is a schematic diagram of the electrodynamic force experienced by the moving contact during the contact phase of multiple pairs of contact fingers. Detailed Implementation

[0043] To make this application more apparent and understandable, preferred embodiments are described in detail below with reference to the accompanying drawings.

[0044] The method for designing and simulating the dynamic stability of grounding switch during short-circuit closing provided in this embodiment is a method for calculating and simulating the dynamic stability of multi-finger knife-type grounding switch during the entire short-circuit closing process based on electromagnetic field finite element simulation technology.

[0045] This method, combined with the design parameters of the grounding switch, firstly meticulously divides the key positions of the contact system during the short-circuit closing process of the multi-finger knife-type grounding switch in the time domain, from the pre-breakdown position of the contact system to the point where multiple pairs of contacts are fully engaged to form a stable electrical contact surface; secondly, it performs time-domain matching of the short-circuit current in the contact system based on the time-domain and position information during the short-circuit closing process of the grounding switch; finally, it performs electromagnetic field finite element simulation analysis on the key positions of the contact system during the short-circuit closing process of the grounding switch, thereby realizing the simulation analysis of the entire short-circuit closing process of the grounding switch.

[0046] The specific steps include:

[0047] Step 1:

[0048] See Figure 2-1 , Figure 2-2 and Figure 2-3 In the time domain, based on the relative positions of the moving and stationary contacts and their contact positions, the short-circuit closing process of a multi-contact finger-type grounding switch is divided into three stages. Figure 2-1 The image shows the pre-breakdown stage. Figure 2-2 The image shows the contact phase of a single pair of fingers. Figure 2-3 The diagram shows the contact phase of multiple pairs of fingers.

[0049] See Figure 3 Obtain the design parameters of the grounding switch, including rated voltage Ue, peak short-circuit current Ich (short-circuit impulse current), rated frequency f, closing speed V1, cutting angle θ1, overtravel preload Fn, and overtravel of moving and stationary contacts H1.

[0050] Step Two:

[0051] The arc pre-breakdown distance L1 is calculated using the rated voltage Ue, where L1 can be obtained from the empirical formula for the breakdown voltage of a uniform electric field gap. In the formula: —Relative density of air, 1 at standard atmospheric pressure; d —Arc pre-breakdown gap, in cm.

[0052] An arc conduction bridge model is established within the arc pre-breakdown distance L1. (See...) Figure 4 ; and the current skin effect, the arrangement of the bridge model for the A / B / C phases is shown in [reference]. Figure 5 .

[0053] Step 3:

[0054] Taking the arc pre-breakdown initiation position as time point 0 on the time domain axis, and combining the arc pre-breakdown distance L1 and the closing velocity V1, the time it takes for the moving contact of the grounding switch to travel through the arc pre-breakdown distance is calculated, which is the arcing time T1. (See [reference]). Figure 6 .

[0055] Step Four:

[0056] Using the parameters designed for the grounding switch, the cutting angle θ1 of the moving contact finger, the closing speed V1, and the overtravel H1 of the moving and stationary contacts, calculate the contact bounce time T2 and contact bounce height h1 of the first pair of contact fingers.

[0057] Step 5:

[0058] The contact bounce height h1 of the first pair of contact fingers is compared with the expected arc breakdown distance L1. If the contact bounce height h1 is less than or equal to the expected arc breakdown distance L1, proceed to step six; if the contact bounce height h1 is greater than the expected arc breakdown distance L1, reduce the cutting angle θ1 of the grounding switch moving contact finger and return to step four for recalculation.

[0059] Step Six:

[0060] The arcing time T1 during the pre-breakdown stage of the grounding switch and the contact bounce time T2 of the first pair of contact fingers are accumulated in the time domain to obtain the continuous arcing time T12. See [reference needed]. Figure 6 .

[0061] Step Seven:

[0062] In the time domain, the short-circuit current value flowing through the grounding switch contact system is matched. The starting point of the arc pre-breakdown start position is taken as the 0 point of the time domain axis and the starting point of the short-circuit current value in the grounding switch contact system is used for matching calculation. The maximum arcing current Id1 generated by the short-circuit current in the time T12 is calculated.

[0063] Step 8:

[0064] The instantaneous electrodynamic values ​​Ffx and Ffy of the contact at the arc root along the contact normal force direction fx and the switch closing direction fy were calculated using electromagnetic field finite element simulation technology when the arc current was Id1. (See [reference needed]). Figure 7 .

[0065] Step Nine:

[0066] Determine the magnitude of the instantaneous electromotive force Ffx along the contact normal pressure direction fx at the contact where the arc root is located, and the magnitude of 1 / N times the overtravel preload Fn of the grounding switch contact (N is recommended to be 2~5). If the instantaneous electromotive force Ffx is less than or equal to 1 / N times the overtravel preload Fn of the grounding switch contact, proceed to step ten; if the instantaneous electromotive force Ffx is greater than 1 / N times the overtravel preload Fn of the grounding switch contact, increase the overtravel H1 of the moving and stationary contacts of the grounding switch, and return to step four to recalculate.

[0067] Step 10:

[0068] For the arcing time T1 during the pre-breakdown stage of the output grounding switch, the contact bounce time T2 of the first pair of contact fingers, the continuous arcing time T12, and the instantaneous electrodynamic values ​​Ffx and Ffy of the contact where the arc root is located along the contact normal pressure direction fx and the switch closing direction fy, please refer to [reference needed]. Figure 7 .

[0069] Step Eleven:

[0070] Calculate the time T3 when the first pair of moving contacts cuts in and the collision and bounce time T4 of the second pair of moving contacts in the same time domain, such as... Figure 6 As shown. And according to the short-circuit current time-domain matching method provided in step seven, the maximum short-circuit current Id2 corresponding to the second pair of moving contacts before the moving contact is cut in is solved.

[0071] Step Twelve:

[0072] Simulation calculations yielded the instantaneous electrodynamic values ​​Fdfx and Fdfy of a single contact finger along the contact normal force direction fx and the switch closing direction fy when a single pair of moving contacts is fully engaged. (See [reference needed]). Figure 8 .

[0073] Step Thirteen:

[0074] Calculate the time T5 when the moving contact of the second pair of contact fingers cuts in and the sliding contact time T6 of the multiple pairs of contact fingers, and calculate the total time Tz for the moving contact to cut in: T1 + ... + T6. See [reference needed]. Figure 6 .

[0075] Step Fourteen:

[0076] Determine the magnitude of the total contact engagement time Tz and the half-time period of the rated current 1 / (2f). If the total contact engagement time Tz is less than or equal to the half-time period of the rated current 1 / (2f), calculate the instantaneous electrodynamic values ​​Fsfx and Fsfy of multiple pairs of contacts along the contact positive pressure direction fx and the switch closing direction fy under the peak short-circuit current Ich. If the total contact engagement time Tz is greater than the half-time period of the rated current 1 / (2f), calculate the instantaneous electrodynamic values ​​Fdfx and Fdfy of a single contact along the contact positive pressure direction fx and the switch closing direction fy under the peak short-circuit current Ich. See [reference needed]. Figure 9 .

[0077] Step Fifteen:

[0078] By comparing the design requirements of the grounding switch, verify whether the instantaneous electrodynamic force on the moving contact during the closing process of the grounding switch meets the design requirements, and give the verification conclusion.

Claims

1. A method for designing and simulating the stability of a grounding switch during short-circuit closing, characterized in that, Includes the following steps: Step 1: Obtain the design parameters of the grounding switch, including rated voltage Ue, peak short-circuit current Ich, rated frequency f, closing speed V1, cutting angle θ1, overtravel preload Fn, and moving and stationary contact overtravel H1. Step 2: Calculate the arc pre-breakdown distance L1 using the empirical formula for the breakdown voltage of a uniform electric field gap and the rated voltage Ue. Step 3: Taking the starting position of the arc pre-breakdown as the 0 point of the time domain axis, and combining the arc pre-breakdown distance L1 and the closing velocity V1, calculate the time it takes for the moving contact of the grounding switch to pass through the arc pre-breakdown distance, which is the arcing time T1. Step 4: Using the parameters designed for the grounding switch, the cutting angle θ1 of the moving contact finger, the closing speed V1, and the overtravel H1 of the moving and stationary contacts, calculate the contact bounce time T2 and contact bounce height h1 of the first pair of contact fingers. Step 5: Compare the contact bounce height h1 of the first pair of contact fingers with the expected arc breakdown distance L1. If the contact bounce height h1 is less than or equal to the expected arc breakdown distance L1, proceed to Step 6; if the contact bounce height h1 is greater than the expected arc breakdown distance L1, reduce the cutting angle θ1 of the grounding switch moving contact finger and return to Step 4 to recalculate. Step 6: Accumulate the arcing time T1 of the grounding switch pre-breakdown stage and the contact bounce time T2 of the first pair of contact fingers in the time domain, which is the continuous arcing time T12. Step 7: Use the short-circuit current time-domain matching method to match the short-circuit current value flowing through the grounding switch contact system in the time domain. Take the arc pre-breakdown start position as the 0 point of the time domain axis as the starting 0 point of the short-circuit current value in the grounding switch contact system for matching calculation, and calculate the maximum arcing current Id1 generated by the short-circuit current in time T12. Step 8: Use electromagnetic field finite element simulation technology to calculate the instantaneous electrodynamic values ​​Ffx and Ffy of the contact where the arc root is located along the contact normal pressure direction fx and the switch closing direction fy when the arc current is Id1; Step 9: Determine the magnitude of the instantaneous electromotive force Ffx of the contact where the arc root is located along the contact normal pressure direction fx and the magnitude of 1 / N times the overtravel preload Fn of the grounding switch contact, where N is 2 to 5; if the instantaneous electromotive force Ffx is less than or equal to 1 / N times the overtravel preload Fn of the grounding switch contact, proceed to Step 10; if the instantaneous electromotive force Ffx is greater than 1 / N times the overtravel preload Fn of the grounding switch contact, increase the overtravel H1 of the moving and stationary contacts of the grounding switch and return to Step 4 to recalculate; Step 10: The arcing time T1 of the first phase of the grounding switch pre-breakdown stage, the contact bounce time T2 of the first pair of contact fingers, the continuous arcing time T12, and the instantaneous electrodynamic values ​​Ffx and Ffy of the contact where the arc root is located along the contact normal pressure direction fx and the switch closing direction fy; Step 11: Calculate the time T3 when the first pair of moving contacts of the contact fingers cut in and the collision and bounce time T4 of the second pair of moving contacts of the contact fingers in the same time domain; and solve for the maximum short-circuit current Id2 before the second pair of moving contacts of the contact fingers cut in according to the short-circuit current time domain matching method provided in Step 7. Step 12: Simulation calculations are performed to obtain the instantaneous electrodynamic values ​​Fdfx and Fdfy of the single contact finger along the contact normal force direction fx and the switch closing direction fy when the single moving contact is fully engaged; Step 13: Calculate the time T5 when the moving contact of the second pair of contact fingers cuts in and the sliding contact time T6 of the multiple pairs of contact fingers, and calculate the total time Tz for the moving contact to cut in: T1 + ... + T6; Step 14: Determine the magnitude of the total contact engagement time Tz and the half-time period of the rated current 1 / (2f); If the total time Tz for the moving contact to engage is less than or equal to half the time period of the rated current 1 / (2f), then calculate the instantaneous electrodynamic values ​​Fsfx and Fsfy of multiple pairs of contact fingers along the contact positive pressure direction fx and the switch closing direction fy under the peak short-circuit current Ich; if the total time Tz for the moving contact to engage is greater than half the time period of the rated current 1 / (2f), then calculate the instantaneous electrodynamic values ​​Fdfx and Fdfy of a single contact finger along the contact positive pressure direction fx and the switch closing direction fy under the peak short-circuit current Ich. Step 15: Compare with the design requirements of the grounding switch, check whether the instantaneous electrodynamic force on the moving contact during the closing process of the grounding switch meets the design requirements, and give the verification conclusion.

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