CN103616537B - A kind of method of lightning protection back brake device and measurement ground capacitance and line electricity sensibility reciprocal - Google Patents

Abstract

The invention discloses a lightning protection switching device, which comprises a test terminal line and a state conversion terminal line, and the test terminal line and the state conversion terminal line are respectively connected to two ends of a power transmission line for testing, wherein: the test terminal The line includes a first current line, a first voltage line, a first ground line, a discharge gap, a double-pole double-throw switch, a first test terminal and a second test terminal; the state conversion terminal line includes a second current line, a second Ground wire, single pole double throw switch, and short state transition terminal block. At the same time, the invention also discloses a method for measuring the ground capacitance and line inductance of the transmission line by using the lightning protection switching device. In the present invention, the double-pole double-throw switch and the single-pole double-throw switch at the two ends of the test line and the state conversion line can be switched to make the line in various states such as grounding, short-circuiting, and suspension, and all states are The conversion can be fully protected by grounding or lightning protection gaps.

Description

A lightning protection switching device and its method for measuring ground capacitance and line inductance

technical field

The present invention relates to the technical field of switching operation of power system substations, in particular to a switch switching device for lightning protection and switching line wiring mode that can be used in the parameter testing process of DC single, double circuit and AC single, double circuit transmission lines. The utility model has the functions of lightning protection and switching the transmission line among multiple states such as grounding, short-circuiting and suspension, and a method for measuring the ground capacitance and line inductance of the transmission line by using the switch switching device.

Background technique

At present, in the domestic transmission line parameter testing process, the conversion and realization of various functions such as grounding, short-circuiting and suspension are all realized by manually changing the wiring mode on the ground or on the gantry. There are no effective risk control measures in terms of casualties and equipment damage. Since there is no permanent lightning protection device during operation and testing, insulating gloves need to be worn during operation, which is cumbersome and time-consuming. More importantly, it cannot guarantee that operators will not be protected from lightning strikes on long-distance lines. In the process of line parameters, there are often problems such as poor on-site operating environment, chaotic line status, and damage to personal and equipment safety caused by lightning strikes.

Contents of the invention

In order to overcome the existing shortcomings that equipment and personal safety cannot be guaranteed when the state is frequently switched during the line parameter test process, and the operation is time-consuming and laborious, one of the purposes of the present invention is to provide a line parameter test lightning protection switching device . The device has the function of switching the line between the test states of grounding, short circuit and suspension under the protection of grounding or lightning protection gap, which can greatly improve the efficiency of line parameter testing and ensure the safety of people and equipment.

For realizing above object, the technical scheme that the present invention has taken is:

A lightning protection switching device, which includes a test end line and a state conversion end line, the test end line and the state conversion end line are respectively connected to the two ends of the transmission line for testing, wherein:

The test terminal circuit includes a first current wire, a first voltage wire, a first ground wire, a discharge gap, a double-pole double-throw switch, a first test terminal and a second test terminal, wherein the double-pole double-throw switch includes a first Fixed terminal, second fixed terminal, third fixed terminal, fourth fixed terminal, first movable contact and second movable contact, wherein one end of the first current line is connected with the first movable contact, and the first voltage line One end of the terminal is connected to the second movable contact, the first fixed terminal and the second fixed terminal are connected to the first ground wire, the third fixed terminal and the fourth fixed terminal are electrically connected to the first test terminal and the second test terminal respectively , the other ends of the first current line and the first voltage line are respectively provided with a first current line connection terminal and a first voltage line connection terminal, and the discharge gap includes a first discharge rod and a second discharge rod having a gap with the first discharge rod. Discharge rods, wherein the first discharge rod is electrically connected to the first current line terminal, the second discharge rod is electrically connected to the first ground wire, and the first current line terminal and the first voltage line terminal are respectively connected to One end of the transmission line is electrically connected;

The state conversion terminal circuit includes a second current wire, a second ground wire, a single-pole double-throw switch and a short-circuit state conversion terminal, wherein the single-pole double-throw switch includes a fifth fixed terminal, a sixth fixed terminal and a first Three movable contacts, the fifth fixed terminal and the sixth fixed terminal are respectively electrically connected to the second grounding wire and the short-circuit state conversion terminal, and one end of the second current wire is electrically connected to the third movable contact, which The other end is provided with a second current wire terminal, and the second current wire terminal is electrically connected with the other end of the power transmission line.

There are at least two transmission lines, and the number of the state conversion end lines and the test end lines are equal to the number of transmission lines, and the state conversion end lines and the test end lines are electrically connected to the two transmission lines one by one. end, and all test end lines are located on the same side of the transmission line.

The test terminal circuit and the state conversion terminal circuit are respectively installed on the first installation board and the second installation board.

The first mounting plate includes a first upper mounting plate and a first lower mounting plate, the first upper mounting plate and the first lower mounting plate are fixed by screws with a gap between them, and the test terminal circuit is installed on the first On the upper mounting plate, the first mounting plate includes a second upper mounting plate and a second lower mounting plate, the second upper mounting plate and the second lower mounting plate are fixed by screws and there is a gap between them, the state transition The terminal circuit is installed on the second upper mounting plate.

Both the first mounting board and the second mounting board are epoxy boards.

The discharge gap further includes a first metal sheet and a second metal sheet parallel to each other, the first discharge rod and the second discharge rod are installed on the first metal sheet and the second metal sheet respectively, and the first discharge rod and the second discharge rod The central axes of the two discharge rods are on the same straight line.

The corresponding positions of the first metal sheet and the second metal sheet are respectively provided with a first through hole and a second through hole, and the first discharge rod and the second discharge rod pass through the first through hole and the second through hole respectively, and the second Both sides of the first through hole and the second through hole are provided with nuts which are threadedly connected with the first discharge rod and the second discharge rod respectively.

Install the test end line and the state conversion end line respectively at both ends of the transmission line to be tested. One end of the lightning protection gap is connected to the measuring instrument, the upper side of the knife switch is connected to the other end of the lightning protection gap and grounded, and the lower side is connected to the line short-circuit state conversion terminal. The protective gap is composed of a discharge rod and a parallel iron sheet, and the gap distance is adjustable. The circuit at the state transition end is to install a number of single-pole double-throw switch switches equal to the number of lines on the insulating plate, and the switch is connected to the line, and the two ends are respectively short-circuited to ground and line-shorted to the state-transition terminal. In the operation conversion state, the operator only needs to use the insulating rod to operate the knife switch, away from the line. During the operation, the person and the instrument are protected by the protection gap. The operation is simple and the status is clear at a glance, avoiding unsafe factors such as complicated wiring on site .

Another object of the present invention is to provide an application of the lightning protection switching device, which is used to measure the capacitance to the ground. In order to achieve this purpose, the technical solution adopted by the present invention is:

Adopting the above-mentioned lightning protection switching device of the claim to carry out the measurement method of ground capacitance, it comprises the following steps:

A. Connect the test end line and the state conversion end line to the two ends of the transmission line respectively;

B. Toggle the first movable contact and the second movable contact to make them electrically connected to the first fixed terminal and the second fixed terminal respectively

C. Toggle the third movable contact to make it suspended;

D. Toggle the first movable contact and the second movable contact so that they are electrically connected to the third fixed terminal and the fourth fixed terminal respectively;

E. The first test terminals are all connected to the current measurement terminals of a measuring instrument, and the second test terminals are all connected to the voltage measurement terminals of the measuring instrument;

F. Turn on the measuring instrument for measurement.

The measuring instrument can be used as a YTLP transmission line power frequency parameter testing system

Another object of the present invention is to provide another application of the lightning protection switching device, which is used to measure the inductance of the line. In order to achieve this object, the technical solution adopted by the present invention is:

The method for measuring the line inductance by using the above-mentioned lightning protection switching device of the claim comprises the following steps:

A. Connect the test end line and the state conversion end line to the two ends of the transmission line respectively;

B. Toggle the first movable contact and the second movable contact so that they are electrically connected to the first fixed terminal and the second fixed terminal respectively;

C. Toggle the third movable contact to make it electrically connected to the second grounding wire;

D. Toggle the first movable contact and the second movable contact, so that the positions of the two are transferred to be electrically connected to the third fixed terminal and the fourth fixed terminal respectively;

E. The first test terminals are all connected to the current measurement terminals of a measuring instrument, and the second test terminals are all connected to the voltage measurement terminals of the measuring instrument;

F. Turn on the measuring instrument for measurement.

Compared with the prior art, the present invention has the advantages of:

1. During the parameter test of the transmission line, the test state can be switched safely and conveniently, through the switches at both ends of the test line and the state conversion line (respectively double-pole double-throw switch and single-pole double-throw switch). The switching operation can make the line in various states such as grounding, short-circuiting and suspension, and all state transitions can be fully protected through grounding or lightning protection gaps.

2. A double-pole double-throw switch is used in the test terminal circuit to separate the voltage line and the current line, which can eliminate the influence of the line down-conductor on the line parameter measurement.

3. The structure of the present invention is simple and the state is clear at a glance, which can greatly improve the on-site test environment, effectively protect people and equipment, and the test process is no longer time-consuming and laborious.

Description of drawings

Fig. 1 is a schematic circuit diagram of a test terminal circuit in a lightning protection switching device of the present invention;

Fig. 2 is the circuit schematic diagram of the state transition end circuit in a kind of lightning protection switching device of the present invention;

Fig. 3 is a schematic diagram of a complete test terminal circuit;

Fig. 4 is a schematic diagram of a complete set of state conversion end circuits;

Fig. 5 is a structural schematic diagram of a discharge gap;

Fig. 6 is the structural representation of epoxy plate;

Fig. 7 is the circuit schematic diagram of the ground capacitance measurement of a single transmission line;

Fig. 8 is the circuit schematic diagram of the ground capacitance measurement of two transmission lines;

Fig. 9 is the circuit schematic diagram of the line inductance measurement of single transmission line;

Fig. 10 is a circuit schematic diagram of capacitance measurement to ground of two transmission lines.

Among them: 1. Test terminal line; 11. Current line; 111. Current line terminal; 12. Voltage line; 121. Voltage line terminal; 13. Discharge gap; 131. Discharge rod; 132. Discharge rod; 133. Metal 134, metal sheet; 14, double pole double throw switch; 141, fixed terminal; 142, fixed terminal; 143, fixed terminal; 144, fixed terminal; 145, movable contact; 146, movable contact; 147, insulation Rod; 15, test terminal; 16, test terminal; 17, ground wire; 2, state conversion terminal line; 21, current line; 211, current line terminal; 22, single-pole double-throw switch; 221, fixed terminal; 222, Fixed terminal; 223, movable contact; 224, insulating rod; 23, short circuit state conversion terminal; 24, ground wire; 3, transmission line; 4, epoxy board; 41, upper mounting plate; 42, lower mounting plate ; 5. Measuring instrument; 6. Fixed plate.

detailed description

The content of the present invention will be described in further detail below in conjunction with the accompanying drawings and specific embodiments.

Example:

A lightning protection switching device, which includes a test terminal circuit 1 and a state conversion terminal circuit 2, wherein:

Please refer to Figure 1 for the circuit schematic diagram of the test terminal line 1, which includes a current line 11, a voltage line 12, a grounding line 17, a discharge gap 13, a double-pole double-throw switch 14, and a test terminal 15 and a test terminal 16, wherein, Double pole double throw switch 14 comprises fixed terminal 141, fixed terminal 142, fixed terminal 143, fixed terminal 144, and movable contact 145 and movable contact 146, and movable contact 145 and movable contact 146 are fixed by an insulating rod 147, make both operate at the same time. One end of the current wire 11 is connected with the movable contact 145, one end of the voltage wire 12 is connected with the movable contact 146, the fixed terminal 141 and the fixed terminal 142 are connected with the ground wire 17, and the fixed terminal 143 and the fixed terminal 144 are respectively connected with the test terminal 15 is electrically connected to the test terminal 16, and the other ends of the current line 11 and the voltage line 12 are respectively provided with a current line connection terminal 111 and a voltage line connection terminal 121. The discharge gap 13 includes a discharge rod 131 and a discharge rod 132 that has a gap with the discharge rod 131. The discharge is performed by relying on the gap formed between the two. The discharge rod 131 is electrically connected to the current wire terminal 111, and the discharge rod 132 is connected to the ground wire 17. electrical connection.

As can be seen from Figure 1, the movable contact 145 and the movable contact 146 of the DPDT switch 14 hit the top and are connected to the discharge rod 132 and grounded, and the movable contact 145 and the movable contact 146 are in the middle even if the voltage line 12 And the current line 11, that is, the transmission line 3 is suspended (there is a protective gap between the ground); and when the movable contact 145 and the movable contact 146 are hit below, it is connected to the test terminal 15 and the test terminal 16 and connected to the test instrument It is also possible to change the wiring mode of the line (two-phase short circuit, three-phase short circuit, etc.) through the terminal leads. The voltage line 12 is not connected to the discharge gap 13, and the other wiring and usage are the same as the current line.

Please refer to Figure 2 for the schematic circuit diagram of the state conversion terminal line 2, which includes a current wire 21, a ground wire 24, a single-pole double-throw switch 22 and a short-circuit state conversion terminal 23, wherein the single-pole double-throw switch 22 includes fixed terminals 221, the fixed terminal 222 and the movable contact 223, an insulating rod 224 is connected on the movable contact 223, the fixed terminal 221, the fixed terminal 222 are electrically connected with the grounding wire 24 and the short-connected state conversion terminal 23 respectively, and the current wire One end of 21 is electrically connected to movable contact 223 , and the other end is provided with current wire connection terminal 211 .

It can be seen from FIG. 2 that the state transition terminal line 2 is only used for state transition, and there is no protection gap and no test wiring. Therefore, a single-pole double-throw switch 22 is used. The current line 21 is electrically connected to the movable contact 223. When the movable contact 223 hits the top, even if the line 2 at the state conversion end is in the grounded state, and the movable contact 223 is in the middle, even if the line is in a suspended state, the movable contact 223 hits the bottom. The wiring mode of the line (two-phase short-circuit, three-phase short-circuit, etc.) can be changed through the short-circuit state conversion terminal 23 .

Please refer to Fig. 7 or shown in Fig. 9, test end line 1 and state conversion end line 2 are respectively connected to the two ends of transmission line 3 to be tested, specifically: current line connection terminal 111 and voltage line connection terminal 121 are respectively connected to the transmission line One end of the line 3 is electrically connected, and the current line terminal 211 is electrically connected to the other end of the transmission line 3 .

Please refer to Figure 3 and Figure 4, there are six test terminal lines and state conversion terminal lines 2, and the ground wires are shared between the test terminal lines and the state conversion terminal lines. This combination structure can complete the DC Line switching function during single, double circuit and AC single, double circuit line parameter testing process.

Please refer to Fig. 5, the discharge gap 13 also includes a metal sheet 133 and a metal sheet 134 fixedly installed on the fixed plate 6 and parallel to each other, the discharge rod 131 and the discharge rod 132 are installed on the metal sheet 133 and the metal sheet 134 respectively, When installing, ensure that the central axes of the discharge rod 131 and the discharge rod 132 are on the same straight line. Specifically, perforations are provided on the metal sheet 133 and the metal sheet 134, and the discharge rod 131 and the discharge rod 132 are correspondingly installed in the corresponding perforations, and two nuts are socketed on the discharge rod 131 and the discharge rod 132 on both sides of the perforation. , the nut is threaded with the corresponding discharge rod 131 and discharge rod 132 to fix the two discharge rods. At the same time, the distance of the discharge gap (that is, the gap between the discharge rod 131 and the discharge rod 132) can be adjusted by adjusting the nut according to the protection strength. In addition, the nuts serve to fix the lead wires connected to the discharge rod 131 and the discharge rod 132 .

Please refer to Fig. 6, the test terminal circuit 1 and the state conversion terminal circuit 2 can be correspondingly installed on the corresponding epoxy board 4, and the epoxy board 4 is composed of an upper mounting board 41 and a lower mounting board 42, wherein the test terminal The line 1 and the state conversion terminal line 2 are installed on the corresponding upper mounting plate 41, and the lower mounting plate 42 is fixed to the upper mounting plate 41 by six screws. There is a certain distance between the two, and the lower mounting plate 42 ensures The components and leads of the upper mounting plate 41 are insulated from the ground, and also play a supporting role. Of course, the number of upper mounting plates 41 can be adjusted according to the line parameter measurement needs, and can be six AC double circuits or four DC double circuits.

Please refer to Fig. 7, to test the ground capacitance of a single transmission line 3, the measurement of the ground capacitance needs to suspend the transmission line 3 to the ground, the method is: turn off the measuring instrument 5, and connect the test terminal 15 to the measuring instrument 5 The current measurement terminal, the test terminal 16 is connected to the voltage measurement terminal of the measuring instrument 5; then the current line terminal 111 and the voltage line terminal 121 are electrically connected to one end of the power transmission line 3 respectively, and the current line terminal 211 is connected to the power transmission line. The other end of the line 3 is electrically connected; toggle the movable contact 145 and the movable contact 146 to electrically connect the two to the fixed terminal 141 and the fixed terminal 142 respectively, so that the transmission line 3 is grounded first; toggle the movable contact 223 to make It is suspended in the air, which is equivalent to ensuring the suspension of the transmission line 3 at this time; toggle the movable contact 145 and the movable contact 146 to electrically connect the two to the fixed terminal 143 and the fixed terminal 144 respectively, that is, to connect the current line 11 to the test terminal 15 , the voltage line 12 is connected to the test terminal 16; the measuring instrument 5 is opened to measure the ground capacitance of the transmission line 3. Wherein, the measuring instrument 5 may adopt a YTLP power frequency parameter test system for transmission lines.

Please refer to Figure 8, when the ground capacitance test is performed on two transmission lines 3 (the situation of more than three is similar, and will not be repeated here), the method is similar to that of a single one, specifically: turn off the measuring instrument 5. Connect the two test terminals 15 in series to the current measuring terminal of the measuring instrument 5, and connect the two test terminals 16 in series to the voltage measuring terminal of the measuring instrument 5; then connect the first test terminal circuit The current line terminal and the voltage line terminal are respectively electrically connected to one end of the first power transmission line, and the current line terminal of the first state conversion end line is electrically connected to the other end of the first power transmission line. Similarly, Electrically connect the current line terminal and the voltage line terminal of the second test line to one end of the second transmission line respectively, and connect the current line terminal of the second state conversion line to the other end of the second transmission line. One end is electrically connected; move the movable contact 145 and the movable contact 146 of the two test ends to make the two electrically connected to the corresponding fixed terminal 141 and fixed terminal 142 respectively, so that the transmission line 3 is grounded first; The movable contact 223 of the state transition end circuit makes it all suspended, which is equal to ensuring the suspension of the two transmission lines at this moment; the movable contact 145 and the movable contact 146 of the two test end circuits are moved to make the two respectively correspond to the corresponding fixed contacts. The terminal 143 is electrically connected with the fixed terminal 144, that is, the current line 11 is connected with the corresponding test terminal 15, and the voltage line 12 is connected with the corresponding test terminal 16; connected together; open the measuring instrument 5 to measure the ground capacitance of the two transmission lines.

Please refer to shown in Fig. 9, carry out line inductance test to single transmission line 3, its method is: close measuring instrument 5, test terminal 15 is connected to the current measuring terminal of measuring instrument 5, and test terminal 16 is connected to this measuring instrument 5; then the current line terminal 111 and the voltage line terminal 121 are electrically connected to one end of the transmission line 3 respectively, and the current line terminal 211 is electrically connected to the other end of the transmission line 3; The point 145 and the movable contact 146 make the two electrically connected to the fixed terminal 141 and the fixed terminal 142 respectively, so that the transmission line 3 is grounded first; The other end of the terminal is grounded; then move the movable contact 145 and the movable contact 146 so that the two are electrically connected to the fixed terminal 143 and the fixed terminal 144 respectively, that is, the current line 11 is connected to the test terminal 15, and the voltage line 12 is connected to the test terminal 16. connected; open the measuring instrument 5 to measure the ground capacitance of the transmission line 3. Here, the movable contact 145 and the movable contact 146 are first moved to electrically connect the two to the fixed terminal 141 and the fixed terminal 142 respectively.

Please refer to Figure 10, when the line inductance test is performed on two transmission lines 3 (the situation of more than three is similar, and will not be repeated here), the method is similar to that of a single one, specifically: turn off the measuring instrument 5. Connect the two test terminals 15 in series to the current measuring terminal of the measuring instrument 5, and connect the two test terminals 16 in series to the voltage measuring terminal of the measuring instrument 5; then connect the first test terminal circuit The current line terminal and the voltage line terminal are respectively electrically connected to one end of the first power transmission line, and the current line terminal of the first state conversion end line is electrically connected to the other end of the first power transmission line. Similarly, Electrically connect the current line terminal and the voltage line terminal of the second test line to one end of the second transmission line respectively, and connect the current line terminal of the second state conversion line to the other end of the second transmission line. One end is electrically connected; move the movable contact 145 and the movable contact 146 of the two test terminals to electrically connect the two to the corresponding fixed terminal 141 and fixed terminal 142 respectively, so that one end of the transmission line 3 is grounded first; The movable contact 223 is connected to the corresponding fixed terminal 221, that is, the other end of the two power transmission lines 3 is grounded; the movable contact 145 and the movable contact 146 of the two test end lines are moved to make the two connect to the corresponding fixed terminal respectively. 143 is electrically connected to the fixed terminal 144, that is, the current line 11 is connected to the corresponding test terminal 15, and the voltage line 12 is connected to the corresponding test terminal 16; together; open the measuring instrument 5 to measure the ground capacitance of the two transmission lines.

It can be seen from the above that in the field test process, firstly, the movable contact 145 and the movable contact 146 should be electrically connected to the corresponding fixed terminal 141 and the fixed terminal 142 respectively, and at the same time, the movable contact 223 should be moved to make it It is connected to the corresponding fixed terminal 221 (even if both ends of the transmission line 3 are grounded), which can ensure the safety of people and equipment during the test wiring and rerouting process. After the wiring is completed, adjust the corresponding switch (that is, double-pole double-throw switch and single-pole double-throw switch) to the corresponding position (grounded, suspended, shorted) to start the test.

The above descriptions are only preferred embodiments of the present invention, and are not intended to limit the present invention. For those skilled in the art, the present invention may have various modifications and changes. Any modifications, equivalent replacements, improvements, etc. made within the spirit and principles of the present invention shall be included within the protection scope of the present invention.

Claims (9)

1. A lightning protection switching device, characterized in that it comprises a test terminal circuit (1) and a state conversion terminal circuit (2), and the test terminal circuit (1) and the state conversion terminal circuit (2) are respectively connected to The two ends of the transmission line (3) are used for testing, wherein: The test terminal circuit (1) includes a first current wire (11), a first voltage wire (12), a first ground wire (17), a discharge gap (13), a double pole double throw switch (14) and a first A test terminal (15) and a second test terminal (16), wherein the double pole double throw switch (14) includes a first fixed terminal (141), a second fixed terminal (142), a third fixed terminal (143), a Four fixed terminals (144), and the first movable contact (145) and the second movable contact (146), wherein one end of the first current line (11) is connected with the first movable contact (145), the first voltage One end of the line (12) is connected to the second movable contact (146), the first fixed terminal (141) and the second fixed terminal (142) are connected to the first grounding wire (17), and the third fixed terminal (143) and the fourth fixed terminal (144) are respectively electrically connected to the first test terminal (15) and the second test terminal (16), and the other ends of the first current line (11) and the first voltage line (12) are respectively provided with The first current line connection terminal (111) and the first voltage line connection terminal (121), the discharge gap (13) includes the first discharge rod (131) and the second discharge rod (131) having a gap with the first discharge rod (131). Rods (132), wherein the first discharge rod (131) is electrically connected to the first current line terminal (111), the second discharge rod (132) is electrically connected to the first ground wire (17), and the first discharge rod (132) is electrically connected to the first ground wire (17). A current line terminal (111) and a first voltage line terminal (121) are respectively electrically connected to one end of the power transmission line (3); The state conversion terminal line (2) includes a second current wire (21), a second ground wire (24), a single-pole double-throw switch (22) and a short-circuit state conversion terminal (23), wherein the single-pole double-throw The throwing switch (22) includes a fifth fixed terminal (221), a sixth fixed terminal (222) and a third movable contact (223), and the fifth fixed terminal (221) and the sixth fixed terminal (222) are connected to the sixth fixed terminal (222) respectively. The two grounding wires (24) are electrically connected to the short-circuit state conversion terminal (23), one end of the second current wire (21) is electrically connected to the third movable contact (223), and the other end is provided with a first Two current wire connection terminals (211), the second current wire connection terminal (211) is electrically connected to the other end of the power transmission line (3). 2. The lightning protection switching device according to claim 1, characterized in that, there are at least two transmission lines (3), and the number of the state conversion end lines (2) and the test end lines (1) are equal to Equal to the number of transmission lines (3), the state conversion end lines (2) and test end lines (1) are electrically connected to the two ends of the transmission line (3), and all test end lines (1) ) are located on the same side of the transmission line (3). 3. The lightning protection switching device according to claim 2, characterized in that, the testing terminal circuit (1) and the state conversion terminal circuit (2) are installed on the first mounting board and the second mounting board respectively. 4. The lightning protection switching device according to claim 3, characterized in that both the first mounting plate and the second mounting plate are epoxy plates (4). 5. The lightning protection switching device according to claim 1, characterized in that, the discharge gap (13) further comprises a first metal sheet (133) and a second metal sheet (134) parallel to each other, the first A discharge rod (131) and a second discharge rod (132) are installed on the first metal sheet (133) and the second metal sheet (134) respectively, and the first discharge rod (131) and the second discharge rod (132) axis are on the same straight line. 6. The lightning protection switching device according to claim 5, characterized in that, the corresponding positions of the first metal sheet (133) and the second metal sheet (134) are respectively provided with a first perforation and a second perforation, The first discharge rod (131) and the second discharge rod (132) pass through the first through hole and the second through hole respectively, and both sides of the first through hole and the second perforation are respectively provided with the first discharge rod ( 131) and the nut that the second discharge rod (132) is threaded. 7. The method for measuring the capacitance to ground by using the lightning protection switching device according to any one of claims 1-6, is characterized in that it comprises the following steps: A, the test terminal circuit (1) and the state conversion terminal circuit (2) are respectively connected to the two ends of the transmission line (3); B. Toggle the first movable contact (145) and the second movable contact (146) so that the two are electrically connected to the first fixed terminal (141) and the second fixed terminal (142); C, toggle the third movable contact (223) to make it suspended; D. Toggle the first movable contact (145) and the second movable contact (146) so that they are electrically connected to the third fixed terminal (143) and the fourth fixed terminal (144) respectively; E, the first test terminal (15) is connected to the current measurement terminal of a measuring instrument (5), and the second test terminal (16) is connected to the voltage measurement terminal of the measuring instrument (5); F, open measuring instrument (5) and measure. 8. The method for measuring the ground capacitance of the lightning protection switching device according to claim 7, characterized in that, the measuring instrument (5) is a YTLP type transmission line power frequency parameter testing system. 9. The method for measuring line inductance using the lightning protection switching device according to any one of claims 1-6, is characterized in that it comprises the following steps: A, the test terminal circuit (1) and the state conversion terminal circuit (2) are respectively connected to the two ends of the transmission line (3); B. Toggle the first movable contact (145) and the second movable contact (146) so that the two are electrically connected to the first fixed terminal (141) and the second fixed terminal (142); C. Toggle the third movable contact (223) to make it electrically connected to the second ground wire (24); D, toggle the first movable contact (145) and the second movable contact (146), so that the positions of the two are transferred to be electrically connected to the third fixed terminal (143) and the fourth fixed terminal (144) respectively; E, the first test terminal (15) is connected to the current measurement terminal of a measuring instrument (5), and the second test terminal (16) is connected to the voltage measurement terminal of the measuring instrument (5); F, open measuring instrument (5) and measure.