A track current difference transformer

Abstract

An inductor for measuring the difference between in-phase currents of tracks, comprising a first iron core for a first lead wire to pass through, a second iron core for a second lead wire to pass through, a first resistor and a second resistor; a coil AB is wound around the first iron core; one end of the coil AB, the first resistor and the other end of the coil AB are electrically connected in sequence; a coil CD is wound around the second iron core; one end of the coil CD, the second resistor and the other end of the coil CD are electrically connected in sequence; when the first lead wire and the second lead wire are respectively connected to a 50 Hz current, magnetic fields are generated in the first iron core and the second iron core, the like-named ends of the coil AB and the coil CD are electrically connected, and the other end of the coil AB and the other end of the coil CD form a measuring end. The present invention makes full use of the flow characteristics of traction current and control signal current in the track section, and can accurately distinguish and measure state quantities such as the amplitude, frequency and phase of various current components.

Description

Technical Field

[0001] The present invention relates to the technical field of railway tracks, and particularly to a track co-directional current difference transformer. Background Art

[0002] In China's electrified railways, railway traction substations convert the high-voltage electricity from the power grid into 25KV, 50Hz alternating current. One pole of the output terminal of the traction transformer is connected to the overhead catenary above the railway, and the other pole is connected to the rail and the ground; electric locomotives obtain electrical energy from the catenary using the pantographs on the roof to pull the train; the driving current of the electric locomotive is called the traction current; the flow path of the traction current is from the traction substation to the catenary, then through the electric locomotive, then through the rail, and finally back to the traction substation through the rail and the ground; there will be 50Hz traction current flowing through the rails of electrified railways.

[0003] In railway stations or sections, choke transformers are often used to divide the tracks into multiple track sections; the midpoints (terminal 3) of adjacent choke transformers are connected to each other, and the terminals 1 and 2 of the choke transformer are respectively connected to the two rails by lead wires; the traction current can be transmitted back to the distant traction substation in sequence through the rail, terminals 1 and 2 of the choke transformer in this section, terminal 3 of the choke transformer in this section, terminal 3 of the adjacent section choke transformer, terminals 1 and 2 of the adjacent section choke transformer, and the adjacent section rail. The control signal current flows within the track section; the flow directions of the traction current and the control signal current are Figure 1 as shown.

[0004] In order to comprehensively monitor the working status of various railway control devices, it is necessary to measure the amplitude, frequency, phase and other state quantities of various component control signal currents and traction currents in the track. One method is to install current transformers in the form of clamp meters at the positions of the first lead wire and the second lead wire of the choke transformer in the figure; however, in actual operation, because the traction current flowing through the first lead wire and the second lead wire is generally relatively large, the maximum value can reach 500A or even higher; moreover, the materials of the first lead wire and the second lead wire are relatively hard and generally do not have extra length reserved, so it is very difficult to test the current difference between the two lead wires by bending the lead wires to form currents in opposite directions within the same transformer core.

[0005] The control signal current is generally relatively small, and the common situation is from 0A to 2A; the difference between the traction current and the control signal current is about 250 times or more; if you want to accurately measure the amplitude, frequency, phase and other state quantities of various control signal current components from the mixed current of a very large traction current and a very small control signal current, it has very high requirements for the accuracy and cost of the current transformer and the subsequent analysis and calculation circuit; for this reason, a track co-directional current difference transformer is proposed in this application. Summary of the Invention

[0006] To solve the technical problems existing in the background art, the present invention proposes a track co-directional current difference mutual inductor. The present invention makes full use of the flow characteristics of the traction current and the control signal current in the track section, significantly improves the measurement conditions, reduces the accuracy and cost requirements of the mutual inductor and the subsequent analysis and calculation circuits, and can accurately distinguish and measure the state quantities such as the amplitude, frequency, and phase of various current components.

[0007] To solve the above problems, the present invention provides a track co-directional current difference mutual inductor, including a first iron core for a first lead wire to pass through, a second iron core for a second lead wire to pass through, a first resistor, and a second resistor;

[0008] A coil AB is wound around the first iron core; one end of the coil AB, the first resistor, and the other end of the coil AB are electrically connected in sequence;

[0009] A coil CD is wound around the second iron core; one end of the coil CD, the second resistor, and the other end of the coil CD are electrically connected in sequence, wherein the second iron core and the first iron core have exactly the same size and structure; the number of turns of the coil CD and the coil AB are exactly the same; the resistance values of the second resistor and the first resistor are the same;

[0010] The 25Hz currents flowing through the first lead wire and the second lead wire have the same direction, the 3000Hz currents flowing through the first lead wire and the second lead wire have the same direction, and the directions of the 50Hz currents flowing through the first lead wire and the second lead wire are the same; wherein, when the first lead wire and the second lead wire are respectively connected to the current, the first iron core and the second iron core generate magnetic fields, the same-named ends of the coil AB and the coil CD are electrically connected, and the other ends of the coil AB and the coil CD form a measurement end for electrically connecting a voltage detection device.

[0011] Preferably, the current value of the 50Hz current is 0 to 500A; the current values of the 25Hz current and the 3000Hz current are both 0 to 2A.

[0012] Preferably, multiple groups of first lead wires penetrate through the same first iron core; the 50Hz currents flowing through the multiple groups of first lead wires have the same direction, the 25Hz currents flowing through the multiple groups of first lead wires have the same direction, and the 3000Hz currents flowing through the multiple groups of first lead wires have the same direction;

[0013] Multiple sets of second lead wires penetrate through the same second iron core; the directions of the 50Hz currents flowing through the multiple sets of second lead wires are the same, the directions of the 50Hz currents flowing through the multiple sets of second lead wires are the same as the directions of the 50Hz currents flowing through the multiple sets of first lead wires 1, the directions of the 25Hz currents flowing through the multiple sets of second lead wires are the same, the directions of the 3000Hz currents flowing through the multiple sets of second lead wires are the same, the directions of the 25Hz currents flowing through the multiple sets of second lead wires are opposite to the directions of the 25Hz currents flowing through the multiple sets of first lead wires, and the directions of the 3000Hz currents flowing through the multiple sets of second lead wires are opposite to the directions of the 3000Hz currents flowing through the multiple sets of first lead wires.

[0014] Preferably, the opposite ends of coil AB and coil CD are electrically connected, and the other ends of coil AB and coil CD form a measurement end for measuring the combined value of the 50Hz currents in the first and second lead wires and for measuring the difference value of the 25Hz currents in the first and second lead wires, and the other ends of coil AB and coil CD form a measurement end for measuring the combined value of the 50Hz currents in the first and second lead wires and for measuring the difference value of the 3000Hz currents in the first and second lead wires.

[0015] Preferably, it further includes a third iron core for the third lead wire to pass through, a third resistor, a fourth resistor, and a fourth iron core for the fourth lead wire to pass through; among them, the first iron core, the second iron core, the third iron core, and the fourth iron core are arranged side by side;

[0016] A coil EF is wound around the third iron core; one end of coil EF, the third resistor, and the other end of coil EF are electrically connected in sequence;

[0017] A coil GH is wound around the fourth iron core; one end of coil GH, the fourth resistor, and the other end of coil GH are electrically connected in sequence;

[0018] The directions of the 25Hz currents flowing through the first and second lead wires are the same, the directions of the 3000Hz currents flowing through the first and second lead wires are the same, the directions of the 25Hz currents flowing through the third and fourth lead wires are the same, the directions of the 3000Hz currents flowing through the third and fourth lead wires are the same, the directions of the 25Hz currents flowing through the third and fourth lead wires are opposite to the directions of the 25Hz currents flowing through the first and second lead wires, and the directions of the 3000Hz currents flowing through the third and fourth lead wires are opposite to the directions of the 3000Hz currents flowing through the first and second lead wires; the directions of the 50Hz currents flowing through the first, second, third, and fourth lead wires are the same;

[0019] When the first lead wire, the second lead wire, the third lead wire, and the fourth lead wire are respectively connected to the 50 Hz current, the A ends, C ends, E ends, and G ends in the coil AB, coil CD, coil EF, and coil GH are denoted as the same-named ends. The A end and the D end, the C end and the E end, and the F end and the G end are sequentially connected, and the B end and the H end form a measurement end for measuring the difference in the 50 Hz current between the first lead wire and the second lead wire and the third lead wire and the fourth lead wire, and for measuring the combined value of the 25 Hz current in the first lead wire and the second lead wire and the third lead wire and the fourth lead wire. The B end and the H end form a measurement end for measuring the difference in the 50 Hz current between the first lead wire and the second lead wire and the third lead wire and the fourth lead wire, and for measuring the combined value of the 3000 Hz current in the first lead wire and the second lead wire and the third lead wire and the fourth lead wire.

[0020] The above technical solution of the present invention has the following beneficial technical effects:

[0021] In the present invention, since the directions and magnitudes of the 50 Hz currents flowing through the first lead wire and the second lead wire are the same, when measuring the voltage at the measurement end formed by the B end and the D end, the induced voltages generated by the 50 Hz currents on the first lead wire and the second lead wire on the second resistor and the first resistor will be substantially cancelled out each other, leaving only the difference voltage.

[0022] Since the directions of the 25 Hz and 3000 Hz currents flowing through the first lead wire and the second lead wire are opposite and the magnitudes are the same, the induced voltages generated by the 25 Hz current and the 3000 Hz current on the first lead wire and the second lead wire on the second resistor and the first resistor will be superimposed on each other, which is twice the induced voltage generated by a single one of the first lead wire or the second lead wire; through the mutual cancellation and mutual enhancement of the above induced voltages, the voltage at the measurement end formed by the B end and the D end can be monitored to measure the 25 Hz current signal, significantly reducing the influence of the 50 Hz current; the present invention can meet the need for detecting the difference in the same-direction current of the track in various situations.

[0023] The present invention makes full use of the flow characteristics of the traction current and the control signal current in the track section, significantly improves the measurement conditions, reduces the accuracy and cost requirements of the current transformer and the subsequent analysis and calculation circuit, and can accurately distinguish and measure the state quantities such as the amplitude, frequency, and phase of various current components. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] Figure 1 It is a flow diagram of the traction current and the control signal current in the existing railway track.

[0025] Figure 2 It is a schematic structural diagram of the first embodiment of a current transformer for detecting the difference in the same-direction current of the track proposed by the present invention.

[0026] Figure 3 This is a schematic structural diagram of the second embodiment of a track co-directional current difference transformer proposed by the present invention.

[0027] Figure 4 This is a schematic structural diagram of the third embodiment of a track co-directional current difference transformer proposed by the present invention.

[0028] Figure 5 This is a schematic structural diagram of the fourth embodiment of a track co-directional current difference transformer proposed by the present invention.

[0029] Reference numerals: 1, first lead wire; 2, first iron core; 3, second lead wire; 4, second iron core; 5, coil AB; 6, first resistor; 7, second resistor; 8, coil CD; 9, third lead wire; 10, third iron core; 11, coil EF; 12, fourth lead wire; 13, fourth iron core; 14, coil GH. Detailed implementation manners

[0030] To make the objectives, technical solutions, and advantages of the present invention clearer and more understandable, the present invention will be further described in detail below in conjunction with specific implementation manners and with reference to the accompanying drawings. It should be understood that these descriptions are merely exemplary and are not intended to limit the scope of the present invention. In addition, in the following descriptions, the descriptions of well-known structures and technologies are omitted to avoid unnecessarily confusing the concepts of the present invention.

[0031] In the first embodiment, as Figure 2 shown, a track co-directional current difference transformer proposed by the present invention includes a first iron core 2 for allowing a first lead wire 1 to pass through, a second iron core 4 for allowing a second lead wire 3 to pass through, a first resistor 6, and a second resistor 7;

[0032] A coil AB5 is wound around the first iron core 2; one end of the coil AB5, the first resistor 6, and the other end of the coil AB5 are electrically connected in sequence;

[0033] A coil CD8 is wound around the second iron core 4; one end of the coil CD8, the second resistor 7, and the other end of the coil CD8 are electrically connected in sequence, wherein the second iron core 4 and the first iron core 2 have exactly the same size and structure; the number of turns of the coil CD8 and the coil AB5 are exactly the same; the resistance values of the second resistor 7 and the first resistor 6 are the same;

[0034] The directions of the 25 Hz current and the 3000 Hz current flowing through the first lead wire 1 and the second lead wire 3 are opposite, and the directions of the 50 Hz current flowing through the first lead wire 1 and the second lead wire 3 are the same; among them, when the first lead wire 1 and the second lead wire 3 are respectively connected to the 50 Hz current, the first iron core 2 and the second iron core 4 generate magnetic fields, and the A ends and C ends in the coil AB5 and the coil CD8 are recorded as the same-name ends; the A end and the C end are electrically connected, and the other end B end of the coil AB5 and the other end D end of the coil CD8 form a measurement end for electrically connecting a voltage detection device;

[0035] Further, the A end and the B end, and the C end and the D end form an auxiliary measurement end.

[0036] In the present invention, because the directions and magnitudes of the 50 Hz currents flowing through the first lead wire 1 and the second lead wire 3 are the same, when measuring the voltage at the measurement end formed by the B end and the D end, the induced voltages generated by the 50 Hz currents on the first lead wire 1 and the second lead wire 3 on the second resistor 7 and the first resistor 6 will basically cancel each other out, leaving only the differential voltage;

[0037] Because the directions of the 25 Hz and 3000 Hz currents flowing through the first lead wire 1 and the second lead wire 3 are opposite and the magnitudes are the same, the induced voltages generated by the 25 Hz current and the 3000 Hz current on the first lead wire 1 and the second lead wire 3 on the second resistor 7 and the first resistor 6 will be superimposed on each other, which is twice the induced voltage generated by a single one of the first lead wire 1 or the second lead wire 3; through the mutual cancellation and mutual enhancement of the above induced voltages, the voltage at the measurement end formed by the B end and the D end can be monitored to measure the 25 Hz current signal, significantly reducing the influence of the 50 Hz current;

[0038] For example, the 50 Hz current flowing through the first lead wire 1 is 500 A, and the 25 Hz current is 1 A; the 50 Hz current flowing through the second lead wire 3 is 480 A, and the 25 Hz current is 1 A;

[0039] If the 25 Hz current is directly measured at the AB end of the coil AB5 or the CD of the coil CD8, it is equivalent to analyzing and calculating the 1 A 25 Hz current under the interference of the 500 A 50 Hz current, and the ratio of the interference signal to the measured signal is 500 times;

[0040] If the 25 Hz signal current is measured at both ends of BD, it is equivalent to analyzing and calculating the 2 A (1 A multiplied by 2 times) 25 Hz current under the interference of the 20 A (500 A minus 480 A) 50 Hz current, and the ratio of the interference signal to the measured signal is 10 times; through the above method, the ratio of the interference signal to the measured signal is reduced by 50 times, and the test conditions can be significantly improved.

[0041] In addition to measuring the 25Hz current at both ends of BD, the difference in the 50Hz current between the first lead wire 1 and the second lead wire 3 can also be directly measured at both ends of BD; at the same time, the 50Hz current value on the first lead wire 1 can be measured on AB, and the 50Hz current value on the second lead wire 3 can be measured on CD; when the 50Hz current is relatively small, the 25Hz current value can also be directly measured at both ends of AB and at both ends of CD as a judgment condition in a special fault state.

[0042] In an optional embodiment, the current value of the 50Hz current is 0 to 500A; the current values of the 25Hz current and the 3000Hz current are 0 to 2A.

[0043] Embodiment 2, as Figure 3 shown, a rail co-directional current difference transformer proposed by the present invention includes a first iron core 2 for the first lead wire 1 to pass through, a second iron core 4 for the second lead wire 3 to pass through, a first resistor 6 and a second resistor 7; wherein, multiple groups of first lead wires 1 penetrate through the same first iron core 2; multiple groups of second lead wires 3 penetrate through the same second iron core 4;

[0044] A coil AB5 is wound around the first iron core 2; one end of the coil AB5, the first resistor 6 and the other end of the coil AB5 are electrically connected in sequence;

[0045] A coil CD8 is wound around the second iron core 4; one end of the coil CD8, the second resistor 7 and the other end of the coil CD8 are electrically connected in sequence, wherein the second iron core 4 and the first iron core 2 have exactly the same size and structure; the number of turns of the coil CD8 and the coil AB5 are exactly the same; the resistance values of the second resistor 7 and the first resistor 6 are the same;

[0046] The directions of the 50Hz currents flowing through the multiple groups of first lead wires 1 are the same, and the directions of the 25Hz currents and the 3000Hz currents flowing through the multiple groups of first lead wires 1 are the same;

[0047] The directions of the 50Hz currents flowing through the multiple groups of second lead wires 3 are the same, the directions of the 50Hz currents flowing through the multiple groups of second lead wires 3 are the same as the directions of the 50Hz currents flowing through the multiple groups of first lead wires 1, the directions of the 25Hz currents and the 3000Hz currents flowing through the multiple groups of second lead wires 3 are the same, and the directions of the 25Hz currents and the 3000Hz currents flowing through the multiple groups of second lead wires 3 are opposite to the directions of the 25Hz currents and the 3000Hz currents flowing through the multiple groups of first lead wires 1;

[0048] When the first lead wire 1 and the second lead wire 3 are respectively connected to a 50 Hz current, a magnetic field is generated in the first iron core 2 and the second iron core 4. The A ends and C ends in the coil AB5 and the coil CD8 are denoted as the same-named ends; the A end and the C end are electrically connected. The other end B of the coil AB5 and the other end D of the coil CD8 form a measurement end for electrically connecting a voltage detection device. That is, at the B end and the D end, the combined value of the 25 Hz current and the 3000 Hz current of multiple groups of the first lead wire 1 and multiple groups of the second lead wire 3 can be detected, and the difference value of the 50 Hz current of multiple groups of the first lead wire 1 and multiple groups of the second lead wire 3 can be detected;

[0049] Further, the A end and the B end, and the C end and the D end form an auxiliary measurement end.

[0050] In an optional embodiment, the current value of the 50 Hz current is 0 - 500 A; the current values of the 25 Hz current and the 3000 Hz current are 0 - 2 A.

[0051] Embodiment 3, as Figure 4 shown, a track co-directional current difference transformer proposed by the present invention includes a first iron core 2 for the first lead wire 1 to pass through, a second iron core 4 for the second lead wire 3 to pass through, a first resistor 6 and a second resistor 7;

[0052] A coil AB5 is wound around the first iron core 2; one end of the coil AB5, the first resistor 6, and the other end of the coil AB5 are electrically connected in sequence;

[0053] A coil CD8 is wound around the second iron core 4; one end of the coil CD8, the second resistor 7, and the other end of the coil CD8 are electrically connected in sequence. Among them, the second iron core 4 and the first iron core 2 have exactly the same size and structure; the number of turns of the coil CD8 and the coil AB5 is exactly the same; the resistance values of the second resistor 7 and the first resistor 6 are the same;

[0054] The directions of the 25 Hz current and the 3000 Hz current flowing through the first lead wire 1 and the second lead wire 3 are opposite, and the directions of the 50 Hz current flowing through the first lead wire 1 and the second lead wire 3 are the same; among them, when the first lead wire 1 and the second lead wire 3 are respectively connected to a 50 Hz current, a magnetic field is generated in the first iron core 2 and the second iron core 4. The A end and the D end in the coil AB5 and the coil CD8 are denoted as different-named ends; the A end and the D end are electrically connected. The other end B of the coil AB5 and the other end C of the coil CD8 form a measurement end for measuring the combined value of the 50 Hz current in the first lead wire 1 and the second lead wire 3 and measuring the difference value of the 25 Hz and 3000 Hz currents in the first lead wire 1 and the second lead wire 3;

[0055] Further, the A end and the B end, and the C end and the D end form an auxiliary measurement end.

[0056] In an optional embodiment, the current value of the 50 Hz current is 0 to 500 A; the current values of the 25 Hz current and the 3000 Hz current are 0 to 2 A.

[0057] Embodiment 4, as Figure 5 As shown, a differential current transformer for track co-directional currents proposed by the present invention includes a first iron core 2 for the first lead wire 1 to pass through, a second iron core 4 for the second lead wire 3 to pass through, a third iron core 10 for the third lead wire 9 to pass through, a fourth iron core 13 for the fourth lead wire 12 to pass through, a third resistor, a fourth resistor, a first resistor 6 and a second resistor 7; wherein, the first iron core 2, the second iron core 4, the third iron core 10 and the fourth iron core 13 are arranged side by side in sequence;

[0058] A coil AB5 is wound around the first iron core 2; one end of the coil AB5, the first resistor 6 and the other end of the coil AB5 are electrically connected in sequence;

[0059] A coil CD8 is wound around the second iron core 4; one end of the coil CD8, the second resistor 7 and the other end of the coil CD8 are electrically connected in sequence;

[0060] A coil EF is wound around the third iron core 10; one end of the coil EF, the third resistor and the other end of the coil EF are electrically connected in sequence;

[0061] A coil GH is wound around the fourth iron core 13; one end of the coil GH, the fourth resistor and the other end of the coil GH are electrically connected in sequence;

[0062] Wherein, the fourth iron core 13, the third iron core 10, the second iron core 4 and the first iron core 2 have exactly the same size and structure; the number of turns of the coil GH, the coil EF, the coil CD8 and the coil AB5 are exactly the same; the resistance values of the fourth resistor, the third resistor, the second resistor 7 and the first resistor 6 are the same;

[0063] The directions of the 25 Hz current and the 3000 Hz current flowing through the first lead wire 1 and the second lead wire 3 are the same, the directions of the 25 Hz current and the 3000 Hz current flowing through the third lead wire 9 and the fourth lead wire 12 are the same, and the directions of the 25 Hz current and the 3000 Hz current flowing through the third lead wire 9 and the fourth lead wire 12 are opposite to the directions of the 25 Hz current and the 3000 Hz current flowing through the first lead wire 1 and the second lead wire 3; the directions of the 50 Hz current flowing through the first lead wire 1, the second lead wire 3, the third lead wire 9 and the fourth lead wire 12 are the same;

[0064] When the first lead wire 1, the second lead wire 3, the third lead wire 9, and the fourth lead wire 12 are respectively connected to the state of 50 Hz current, the A ends, C ends, E ends, and G ends in the coil AB5, the coil CD8, the coil EF, and the coil GH are denoted as the same-name ends, and the A end, D end, E end, and H end are connected in sequence.

[0065] Then, the B end and the H end form a measurement end for measuring the difference in 50 Hz current between the first lead wire 1 and the second lead wire 3 and the third lead wire 9 and the fourth lead wire 12 (that is, the difference between the sum of the 50 Hz current values in the first lead wire 1 and the second lead wire 3 and the sum of the 50 Hz current values in the third lead wire 9 and the fourth lead wire 12).

[0066] And a measurement end for measuring the combined value of the 25 Hz current in the first lead wire 1 and the second lead wire 3 and the third lead wire 9 and the fourth lead wire 12 (that is, the 25 Hz current value in the first lead wire 1 + the 25 Hz current value in the second lead wire 3 + the 25 Hz current value in the third lead wire 9 + the 25 Hz current value in the fourth lead wire 12).

[0067] In an optional embodiment, the current value of the 50 Hz current is 0 - 500 A; the current values of the 25 Hz current and the 3000 Hz current are 0 - 2 A.

[0068] It should be understood that the above specific embodiments of the present invention are only used for exemplary illustration or explanation of the principle of the present invention, and do not constitute a limitation to the present invention. Therefore, any modifications, equivalent replacements, improvements, etc. made without departing from the spirit and scope of the present invention shall be included within the protection scope of the present invention. In addition, the appended claims of the present invention are intended to cover all changes and modification examples falling within the scope and boundaries of the appended claims, or equivalent forms of such scope and boundaries.

Claims

1. An in-orbit co-directional current difference transformer, characterized in that, It includes a first iron core (2) for a first lead wire (1) to pass through, a second iron core (4) for a second lead wire (3) to pass through, a first resistor (6) and a second resistor (7); A coil AB (5) is wound around the first iron core (2); one end of the coil AB (5), the first resistor (6) and the other end of the coil AB (5) are electrically connected in sequence; A coil CD (8) is wound around the second iron core (4); one end of the coil CD (8), the second resistor (7) and the other end of the coil CD (8) are electrically connected in sequence, wherein the second iron core (4) and the first iron core (2) have exactly the same size and structure; the number of turns of the coil CD (8) and the coil AB (5) are exactly the same; the resistance values of the second resistor (7) and the first resistor (6) are the same; The 25 Hz currents flowing through the first lead wire (1) and the second lead wire (3) have the same direction, the 3000 Hz currents flowing through the first lead wire (1) and the second lead wire (3) have the same direction, and the directions of the 50 Hz currents flowing through the first lead wire (1) and the second lead wire (3) are the same; wherein, when the first lead wire (1) and the second lead wire (3) are respectively connected to the current, the first iron core (2) and the second iron core (4) generate magnetic fields, the like-named ends of the coil AB (5) and the coil CD (8) are electrically connected, and the other end of the coil AB (5) and the other end of the coil CD (8) form a measurement end for electrically connecting a voltage detection device.

2. The differential current transformer for the same-direction current of the track according to claim 1, characterized in that The current value of the 50 Hz current is 0 - 500 A; the current values of the 25 Hz current and the 3000 Hz current are both 0 - 2 A.

3. The differential current transformer for same-direction currents on a track according to claim 1, wherein Multiple groups of first lead wires (1) pass through the same first iron core (2); the directions of the 50 Hz currents flowing through the multiple groups of first lead wires (1) are the same, the directions of the 25 Hz currents flowing through the multiple groups of first lead wires (1) are the same, and the directions of the 3000 Hz currents flowing through the multiple groups of first lead wires (1) are the same; Multiple groups of second lead wires (3) pass through the same second iron core (4); the directions of the 50 Hz currents flowing through the multiple groups of second lead wires (3) are the same, the directions of the 50 Hz currents flowing through the multiple groups of second lead wires (3) are the same as the directions of the 50 Hz currents flowing through the multiple groups of first lead wires (1), the directions of the 25 Hz currents flowing through the multiple groups of second lead wires (3) are the same, the directions of the 3000 Hz currents flowing through the multiple groups of second lead wires (3) are the same, the directions of the 25 Hz currents flowing through the multiple groups of second lead wires (3) are opposite to the directions of the 25 Hz currents flowing through the multiple groups of first lead wires (1), and the directions of the 3000 Hz currents flowing through the multiple groups of second lead wires (3) are opposite to the directions of the 3000 Hz currents flowing through the multiple groups of first lead wires (1).

4. A differential current transformer for track co-directional currents according to claim 1, characterized in that, The opposite ends of coil AB (5) and coil CD (8) are electrically connected, and the other ends of coil AB (5) and coil CD (8) form a measuring end for measuring the combined value of 50 Hz current in the first lead wire (1) and the second lead wire (3) and the difference value of 25 Hz current in the first lead wire (1) and the second lead wire (3), and also form a measuring end for measuring the combined value of 50 Hz current in the first lead wire (1) and the second lead wire (3) and the difference value of 3000 Hz current in the first lead wire (1) and the second lead wire (3).

5. A differential current transformer for same-direction currents in a track according to claim 1, characterized in that It further includes a third iron core (10) for the third lead wire (9) to pass through, a third resistor, a fourth resistor, and a fourth iron core (13) for the fourth lead wire (12) to pass through; wherein, the first iron core (2), the second iron core (4), the third iron core (10), and the fourth iron core (13) are arranged side by side; A coil EF is wound around the third iron core (10); one end of the coil EF, the third resistor, and the other end of the coil EF are electrically connected in sequence; A coil GH is wound around the fourth iron core (13); one end of the coil GH, the fourth resistor, and the other end of the coil GH are electrically connected in sequence; The flowing directions of the 25 Hz currents respectively flowing through the first lead wire (1) and the second lead wire (3) are the same, the flowing directions of the 3000 Hz currents respectively flowing through the first lead wire (1) and the second lead wire (3) are the same, the flowing directions of the 25 Hz currents respectively flowing through the third lead wire (9) and the fourth lead wire (12) are the same, the flowing directions of the 3000 Hz currents respectively flowing through the third lead wire (9) and the fourth lead wire (12) are the same, the direction of the 25 Hz current respectively flowing through the third lead wire (9) and the fourth lead wire (12) is opposite to the direction of the 25 Hz current respectively flowing through the first lead wire (1) and the second lead wire (3), the direction of the 3000 Hz current respectively flowing through the third lead wire (9) and the fourth lead wire (12) is opposite to the direction of the 3000 Hz current respectively flowing through the first lead wire (1) and the second lead wire (3); the flowing directions of the 50 Hz currents respectively flowing through the first lead wire (1), the second lead wire (3), the third lead wire (9), and the fourth lead wire (12) are the same; When the first lead wire (1), the second lead wire (3), the third lead wire (9), and the fourth lead wire (12) are respectively connected to the state of the 50 Hz current, the A end, the C end, the E end, and the G end in the coil AB (5), the coil CD (8), the coil EF, and the coil GH are denoted as the same-named ends, and the A end and the D end, the C end and the E end, and the F end and the G end are sequentially connected. The B end and the H end form a measurement end for measuring the difference in the 50 Hz current between the first lead wire (1) and the second lead wire (3) and the third lead wire (9) and the fourth lead wire (12), and for measuring the combined value of the 25 Hz current in the first lead wire (1) and the second lead wire (3) and the third lead wire (9) and the fourth lead wire (12). The B end and the H end form a measurement end for measuring the difference in the 50 Hz current between the first lead wire (1) and the second lead wire (3) and the third lead wire (9) and the fourth lead wire (12), and for measuring the combined value of the 3000 Hz current in the first lead wire (1) and the second lead wire (3) and the third lead wire (9) and the fourth lead wire (12).

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