Digital display type grounding current measuring device

Abstract

A digital display type grounding current measuring device comprises a grounding copper bar, a plurality of groups of detection units are arranged on the grounding copper bar, and each detection unit comprises a binding post connected with the grounding copper bar and a current transformer. And a plurality of current displays are arranged in the display station, and the current displays are in one-to-one correspondence with the current transformers and are connected with the current transformers. The utility model provides a digital display type grounding current measuring device, which can solve the problem that the existing grounding copper bar can only realize grounding and cannot detect the grounding uniqueness and reliability of a secondary circuit. When only one point of the secondary circuit is reliably grounded, the current value of the secondary circuit is less than 1mA; when multipoint grounding exists in the secondary circuit, the current value is far greater than a normal value, and the specific value is determined according to the difference between two grounding potential values; and when the grounding point of the secondary circuit is not reliable in grounding, the current value is 0.

Description

Technical Field

[0001] The utility model relates to the technical field of transformer secondary circuit detection, in particular to a digital display type ground current measuring device. Background Art

[0002] Article 18.6.2.1 of the "Twenty-Five Key Requirements for Preventing Power Production Accidents (2023 Edition)" stipulates that "the secondary circuit of a current transformer or voltage transformer can only have one grounding point."

[0003] The secondary circuit of a transformer must have a grounding point to protect personnel and secondary equipment. If the secondary circuit lacks a grounding point, the high voltage connected to the primary side will create a voltage through the distributed capacitance between the secondary windings and the secondary circuit's capacitance to ground, introducing the high voltage into the secondary circuit. If the secondary circuit has a grounding point, the secondary circuit capacitance is short-circuited, and the voltage distributed to the high-voltage side of the secondary circuit is zero, thus protecting personnel and secondary equipment.

[0004] A TA secondary circuit can only have one grounding point. If there are grounding points on either side of the relay's current coil in the TA secondary circuit, the parallel circuit formed by the two grounding points and the ground will bypass the current coil, causing a shunt and reducing the current flowing through the coil. Furthermore, in the event of a ground fault, the potential difference between the two grounding points will generate additional current in the current coil. Both of these factors can cause a significant difference between the current flowing through the relay and the current flowing into the TA secondary, potentially causing the relay protection device to malfunction.

[0005] The TV secondary circuit can only have one grounding point. When a ground fault occurs in the grid, high current flowing through the ground grid can cause the voltage zero point to shift, potentially leading to voltage distortion and misoperation or failure of protective devices. If the grounded neutral conductor is broken, causing poor contact with the N600, this can also cause the neutral point voltage phase to shift.

[0006] There are many reasons for multiple grounding in transformer secondary circuit failures: 1) During protection installation, the secondary neutral point of the transformer, with two sets of dual protection screens, may be grounded at different points, resulting in multiple grounding. 2) During technical upgrades or expansion projects, due to errors in drawings or human negligence, the secondary circuit may be mistakenly connected to another circuit, resulting in multiple grounding. 3) Improper use of experimental equipment during commissioning can cause multiple grounding. 4) The secondary neutral circuit ground wire may already be connected to the grounding busbar when the equipment leaves the factory. During installation, it may be grounded at one point by connecting to the grounding grid, and then grounded at other circuit panels, resulting in multiple grounding. 5) Due to insufficient technical skills, construction workers may damage the conductor insulation, resulting in multiple neutral grounding.

[0007] Currently, the reliability and uniqueness of the transformer secondary circuit grounding point can only be checked when the equipment is shut down for maintenance. The inspection steps are as follows:

[0008] (1) After confirming that there is no current or voltage in the circuit, remove the known grounding wire identified in the secondary circuit.

[0009] (2) Disconnect the current (voltage) terminal connectors in the local terminal box and the protection panel cabinet to divide the entire TA (TV) secondary circuit into several controllable sections;

[0010] (3) According to the principle of "first outdoor cables, then the main unit, and finally indoor cabinets", measure the insulation resistance of each section of the circuit to ground. If the insulation resistance of all sections to ground is qualified, it can be confirmed that there are no other grounding points in the entire circuit except the determined grounding point. If the insulation resistance of a section to ground is unqualified, there is a second grounding point in the detection range of this section.

[0011] (4) After confirming the uniqueness of the secondary circuit, restore the known grounding wire that has just been removed.

[0012] (5) Measure the insulation resistance to ground at any point in the entire circuit. If the insulation is zero, the grounding point of the circuit is reliable, otherwise it is unreliable.

[0013] The existing inspection process can be summarized as: remove grounding, disconnect, measure section by section to confirm uniqueness, restore grounding, and measure to confirm reliability. This troubleshooting process requires covering all panels involved in each winding, and requires a section-by-section inspection, which is not intuitive. Relying on a section-by-section inspection method using an insulation meter, the inspection process is labor-intensive and inefficient. Summary of the Invention

[0014] The technical problem to be solved by the utility model is to provide a digital display grounding current measuring device to solve the problem that the existing grounding copper busbar can only realize the grounding function but cannot detect the uniqueness and reliability of the entire secondary circuit grounding.

[0015] In order to solve the above technical problems, the technical solution adopted by the utility model is: a digital ground current measuring device, including a grounding copper busbar, on which are provided a plurality of detection units, the detection units including terminals connected to the grounding copper busbar and current transformers; and also including a display stand, in which a plurality of current displays are provided, and the current displays correspond one-to-one to the current transformers and are connected thereto.

[0016] Preferably, it also includes a base, a grounding copper bar and a display stand are arranged on the base, the bottom of the current transformer passes through the grounding copper bar and extends into the base, and the wire connects the current transformer and the current display through the base.

[0017] Preferably, one end of the grounding copper busbar extends to the outside of the base and is provided with a grounding bolt.

[0018] This utility model provides a digital ground current measurement device that overcomes the shortcomings of existing grounding copper bars, which only provide grounding but cannot detect the uniqueness and reliability of secondary circuit grounding. When only one point in the secondary circuit is reliably grounded, the current value is less than 1mA; when multiple points in the secondary circuit are grounded, the current value is much higher than normal, and the specific value depends on the potential difference between the two grounds; when the grounding point in the secondary circuit is unreliable, the current value is 0.

[0019] This digital display type ground current dedicated grounding can monitor the uniqueness and reliability of the secondary circuit grounding in real time, reducing the maintenance personnel's work of troubleshooting the transformer secondary circuit grounding point, improving the safe and stable operation level of the equipment, and has practical value. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] The present invention will be further described below with reference to the accompanying drawings and embodiments:

[0021] Figure 1 It is a structural diagram of the present utility model. DETAILED DESCRIPTION

[0022] like Figure 1 As shown, a digital ground current measuring device includes a grounding copper busbar 1, on which multiple detection units are provided. The detection units include a terminal 2 connected to the grounding copper busbar 1 and a current transformer 3; and also includes a display stand 4. The display stand 4 is provided with multiple current displays 5. The current displays 5 correspond to the current transformers 3 one by one and are connected thereto.

[0023] Preferably, it also includes a base 6, the grounding copper bus 1 and the display stand 4 are arranged on the base 6, the bottom of the current transformer 3 passes through the grounding copper bus 1 and extends into the base 6, and the wire connects the current transformer 3 and the current display 5 through the base 6.

[0024] Preferably, one end of the grounding copper bus 1 extends to the outside of the base 6 and is provided with a grounding bolt 7 .

[0025] When in use, install the device at the bottom of the panel cabinet of the microcomputer protection and control device, and the grounding copper bar 1 should have a cross-sectional area of not less than 100mm 2 The cross-sectional area of the grounding terminal of all devices, cable shielding layers and cabinet doors in the cabinet shall not be less than 4mm 2 Connect multiple strands of copper wire to it, each wire passing through a current transformer 3 before connecting to terminal 2. The through-hole current transformer 3 is used to collect the current in the grounding wire of the voltage and current secondary circuit. The current display 5, current transformer 3, and terminal 2 should be wired in a one-to-one correspondence. The current display 5 displays the grounding current value of the grounding wire.

[0026] The above embodiments are merely preferred technical solutions of the present invention and should not be construed as limiting the present invention. The scope of protection of the present invention shall be the technical solutions set forth in the claims, including equivalent alternatives to the technical features of the technical solutions set forth in the claims. Equivalent alternatives and improvements within this scope are also within the scope of protection of the present invention.

Claims

1. A digital ground current measuring device, characterized in that: The invention comprises a grounding copper busbar (1), on which a plurality of detection units are arranged, wherein the detection units comprise a terminal (2) connected to the grounding copper busbar (1) and a current transformer (3); and a display stand (4), wherein a plurality of current displays (5) are arranged in the display stand (4), and the current displays (5) correspond to the current transformers (3) one by one and are connected thereto.

2. The digital ground current measuring device according to claim 1, characterized in that: The device further comprises a base (6), a grounding copper busbar (1) and a display stand (4) are arranged on the base (6), the bottom of the current transformer (3) passes through the grounding copper busbar (1) and extends into the base (6), and a wire connects the current transformer (3) and the current display (5) through the base (6).

3. The digital ground current measuring device according to claim 2, characterized in that: One end of the grounding copper busbar (1) extends to the outside of the base (6) and is provided with a grounding bolt (7).

Images