CN111521930B

CN111521930B - A fault current limiting resistor and fault current detection device

Info

Publication number: CN111521930B
Application number: CN202010402716.XA
Authority: CN
Inventors: 信天; 李洪亮; 李海成; 张超; 田列远; 员雪峰
Original assignee: Shandong Institute for Product Quality Inspection
Current assignee: Shandong Institute for Product Quality Inspection
Priority date: 2020-05-13
Filing date: 2020-05-13
Publication date: 2021-05-11
Anticipated expiration: 2040-05-13
Also published as: CN111521930A

Abstract

The present disclosure provides a fault current limiting resistor and a fault current detection device. The fault current limiting resistor provided by the present disclosure has a fusing time of 2 cycles at a current of 1500A, which is only one and a half times later than the copper wire used for the fusing element. It can meet the requirement that the fuse element is blown first, and the fault current detection device can realize the detection of multiple fault currents, and can support the test under different fault currents.

Description

Fault current limiting resistor and fault current detection device

Technical Field

The disclosure belongs to the technical field of fault current detection, and particularly relates to a fault current limiting resistor and a fault current detection device.

Background

The statements in this section merely provide background information related to the present disclosure and may not necessarily constitute prior art.

Low-voltage switching devices and control devices typically include circuit breakers, low-voltage switches, isolators, disconnecting switches, fuse-breakers, contactors, motor starters, terminal blocks, automatic transfer switching devices, and the like. The circuit is mainly used for switching on and switching off a circuit with rated voltage of alternating current not more than 1000V or direct current not more than 1500V.

GB/T14048.1-2012 "low-voltage switchgear and control apparatus part 1: the general rules are the national standards of the products, all rules and requirements of basic performances of various low-voltage switching devices and control devices are specified in detail in the standards, the connection and disconnection capacities and the short-circuit connection and disconnection capacities are test items which must be carried out in the product inspection of various low-voltage switching devices and control devices, and fault current detection is required in the connection and disconnection capacity test and the performance test under the short-circuit condition.

The detection circuit of the fault current is provided with two parts according to the standard: fuse element, fault current limiting resistor. The fusing element adopts a copper wire with a certain diameter and at least 50mm of length or an equivalent fusing body. The diameters of the three-phase current transformer correspond to the expected fault currents one to one, and the following table is shown:

comparison table of diameter of copper wire of fusing element and expected fault current

Diameter of copper wire (mm)	Anticipating fault current (A) in a fuse element circuit
		0.1	50
0.2	150
		0.3	300
0.4	500
		0.5	800
0.8	1500

The standard states that a copper wire with a diameter of 0.8mm will blow (or about 0.01s for dc) over about half a cycle when passing 1500A current at a frequency between 45Hz and 67 Hz.

The specification and technical requirements of the fault current limiting resistor are not specified in the standard, but it is not difficult to know that the fault current limiting resistor can blow at least later than the fuse element when 1500A current with the frequency between 45Hz and 67Hz is passed through the fault current detecting circuit, and the fault current is limited within 1500(1 +/-10%) A (or within the magnitude range of other classes of fault current).

Typically, the low voltage switchgear and control device voltage ratings are most commonly two levels of 400V, 690V. Taking the rated voltage level of 400V as an example, the voltage applied to the fault detection circuit is 230V. When fault current 1500A is conducted, its fault detection circuit instantaneous power requirement will exceed 345kW, while its limiting fault current resistance is only 150m Ω or less in magnitude.

To the knowledge of the inventors, the high power resistors currently available on the market can only withstand about tens of watts, up to hundreds of watts, at a size of 150m Ω. Also the volume of the individual resistors is large and the higher the power requirement, the larger the volume and the more difficult it is to achieve a variable resistor size. To meet the test requirements, a large number of commonly used high power resistors must be used for complex series-parallel connections. This greatly limits the convenience of such resistors and further increases their cost. Moreover, at least 6 or more fault detection circuits are required for each test. Therefore, the conventional fault current limiting resistor made of a high-power resistor is extremely heavy, high in cost and difficult to adjust the size, so that the operability is extremely poor.

Disclosure of Invention

In order to solve the problem, the limiting fault current resistor and the fault current detection device are provided, and the limiting fault current resistor provided by the disclosure has the advantages that the fusing time is 2 cycles at the current of 1500A, only 1 half cycle later than a copper wire for the fusing element is provided, the requirement of fusing the fusing element firstly can be met, meanwhile, the fault current detection device can realize the detection of multiple paths of fault currents, and the tests under different sizes of fault currents can be supported.

According to some embodiments, the following technical scheme is adopted in the disclosure:

firstly, the invention provides a fault current limiting resistor which comprises four resistance wires, wherein the resistance wires are spirally wound together around the same central line along the same direction, and the resistance wires are in close contact with each other, so that the resistor is integrally distributed in a straight line.

As an alternative embodiment, the resistance wire is made of alloy materials, and Cr30Ni70 alloy is selected.

As an alternative embodiment, the wire diameter of the resistance wire is 0.8-1.0 mm. As an alternative embodiment, the angle of inclination of the resistance wire to the centre line is 30-60 deg..

Secondly, the fault current detection device comprises an insulating plate, wherein a plurality of rows of test loops and bus bars are arranged on one surface of the insulating plate, each test loop comprises the fault current limiting resistor, the first end of each fault current limiting resistor is connected with the corresponding bus bar through a fuse element, and a scribing device is arranged on each fault current limiting resistor in a sliding mode and is connected to corresponding fault current detection points through the scribing device;

the another side of insulation board is provided with a plurality of rows of link ends group, and every link end group includes two at least stiff ends for installation fuse element, and one of them stiff end is connected with busbar, another stiff end with first end is connected.

In an alternative embodiment, the number of test loops is not less than 6.

As an alternative embodiment, the scribing device is a scriber and comprises a movable body and a connecting line, wherein the movable body can slide and stop at any position on the fault current resistor for conveniently adjusting and limiting the size of the fault current resistor, and the movable body is provided with the connecting line which is connected with the corresponding fault current detection point.

In an alternative embodiment, the fault current detection points include a plurality of points corresponding to the test loops one to one.

As an alternative embodiment, the device further comprises a support, and the insulating plate is arranged on the support.

As an alternative embodiment, the fault current limiting resistor is arranged on the insulating plate by two fixed ends.

Compared with the prior art, the beneficial effect of this disclosure is:

the resistance wire material used for manufacturing the fault current limiting resistor is an alloy, and is low in cost. The fault current limiting resistor is in a straight shape and brings the least inductance. Under 1500A current, the fusing time is 2 cycles, which is 1 half cycle later than that of a copper wire used for the fusing element, so that the requirement of fusing the fusing element first is met.

The fault current limiting resistor provided by the disclosure has the advantages of small volume, simple manufacture and low cost, and can conveniently realize the adjustable resistance size through a simple marking device, and is used for supporting tests under different fault currents.

The multi-path fault current detection can be realized simultaneously, and the method is simple, practical and high in test efficiency.

Drawings

The accompanying drawings, which are included to provide a further understanding of the disclosure, illustrate embodiments of the disclosure and together with the description serve to explain the disclosure and are not to limit the disclosure.

FIG. 1 is a schematic diagram of a fault current limiting resistor winding process of the present disclosure;

fig. 2 is a schematic view of a-plane structure of the fault current detection apparatus of the present disclosure;

fig. 3 is a schematic B-plane structure diagram of the fault current detection apparatus of the present disclosure;

wherein: 1. busbar, 2, link A, 3, restriction fault current resistor, 4, marking device, 5, connecting wire, 6, link B, 7, support, 8, link C, 9, link D, 10, fuse element, 11, insulation board.

The specific implementation mode is as follows:

the present disclosure is further described with reference to the following drawings and examples.

It should be noted that the following detailed description is exemplary and is intended to provide further explanation of the disclosure. Unless defined otherwise, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this disclosure belongs.

It is noted that the terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting of example embodiments according to the present disclosure. As used herein, the singular forms "a", "an" and "the" are intended to include the plural forms as well, and it should be understood that when the terms "comprises" and/or "comprising" are used in this specification, they specify the presence of stated features, steps, operations, devices, components, and/or combinations thereof, unless the context clearly indicates otherwise.

In the present disclosure, terms such as "upper", "lower", "left", "right", "front", "rear", "vertical", "horizontal", "side", "bottom", and the like indicate orientations or positional relationships based on those shown in the drawings, and are only relational terms determined for convenience in describing structural relationships of the parts or elements of the present disclosure, and do not refer to any parts or elements of the present disclosure, and are not to be construed as limiting the present disclosure.

In the present disclosure, terms such as "fixedly connected", "connected", and the like are to be understood in a broad sense, and mean either a fixed connection or an integrally connected or detachable connection; may be directly connected or indirectly connected through an intermediate. The specific meanings of the above terms in the present disclosure can be determined on a case-by-case basis by persons skilled in the relevant art or technicians, and are not to be construed as limitations of the present disclosure.

As shown in fig. 1, the fault current limiting resistor, in this embodiment, is made of the following materials: the wire diameter of the Cr30Ni70 alloy is 0.90mm, the weight per meter is 0.005153kg/m, and the resistance per meter is 1.855 omega/m (at 20 ℃).

The winding mode of the fault current limiting resistor is that four resistance wires are simultaneously and tightly wound, and no large gap exists in the middle of the resistance wires.

The winding completed resistor is arranged linearly, so that inductive reactance generated by spiral arrangement is avoided, and the integral resistance value is larger than the pre-test measurement value.

As shown in fig. 2, a fault current detection device includes a support 7 and an insulating plate 11 disposed thereon, wherein a plurality of rows of test circuits and bus bars 1 are disposed on one surface of the insulating plate 11, each test circuit includes a fault current limiting resistor 3, and two ends of the fault current limiting resistor 3 are respectively fixed on two connecting ends. The first end of the fault current limiting resistor 3 is wound or fixed on the connection terminal a2, and is connected to the busbar 1 through the fuse element 10. During testing, in each fault current detection loop, the connection end A2 of the fault current limiting resistor is connected to the busbar 1 through a lead. Then, the busbar 1 is connected to the test circuit neutral point or the artificial neutral point. And the simultaneous detection of multiple paths of fault currents in the test is realized.

The support 7 comprises a base and two support frames arranged on the base, and the two support frames are respectively positioned on two sides of the insulating plate 11.

The fault current limiting resistor 3 is provided with a scribing device 4 in a sliding way, and the scribing device 4 is connected to a connection terminal B6, and a connection terminal B6 is connected to a corresponding fault current detection point;

as shown in fig. 3, a plurality of rows of connection terminal groups are arranged on the other surface of the insulating plate, each connection terminal group includes at least two fixed terminals (i.e., a connection terminal C8 and a connection terminal D9, where the connection terminal D9 is connected to a connection terminal a2 of a fixed point at one end of the fault current limiting resistor), a fuse element 10 is installed between the connection terminal C8 and the connection terminal D9, where the connection terminal C8 is connected to the busbar 1, and the connection terminal D9 is connected to the connection terminal a 2.

In this embodiment, the fuse element 10 is a copper wire, and fuse elements of different diameters can be replaced as required in each test.

The insulating plate 11 may be an epoxy insulating plate.

During the test, in each fault current detection loop, the current flowing route is as follows: the test sample fault current detection point comprises a test sample fault current detection point, a connecting end B6, a connecting lead 5, a scribing device 4, a fault current limiting resistor 3, a connecting end A2 (namely a connecting end D9), a fuse element 10, a connecting end C8, a busbar 1 and a test voltage neutral point or an artificial neutral point.

The fault detection device has the advantages that the resistor for limiting the fault current is small in size, simple to manufacture and low in cost, and the resistor can be adjusted conveniently through the simple marking device, so that tests under the fault currents of different sizes can be supported.

Because the resistor for limiting the fault current is small in size, the detection of the fault current of 6 paths or even more paths can be conveniently realized.

The resistance wire material used for manufacturing the fault current limiting resistor is generally used for manufacturing electric furnaces, is common and has low cost.

The fault current limiting resistor is in a straight line shape, and the inductance is minimum.

The resistor limits the fault current, under 1500A current, the fusing time is 2 cycles, and only 1 half cycle later than the copper wire for the fusing element just meets the requirement that the fusing element fuses firstly. The device is suitable for testing low-voltage switch equipment and control equipment.

The above description is only a preferred embodiment of the present disclosure and is not intended to limit the present disclosure, and various modifications and changes may be made to the present disclosure by those skilled in the art. Any modification, equivalent replacement, improvement and the like made within the spirit and principle of the present disclosure should be included in the protection scope of the present disclosure.

Although the present disclosure has been described with reference to specific embodiments, it should be understood that the scope of the present disclosure is not limited thereto, and those skilled in the art will appreciate that various modifications and changes can be made without departing from the spirit and scope of the present disclosure.

Claims

1. a fault current detection device is characterized in that: comprise an insulating plate, one side of the insulating plate is provided with multiple rows of test loops and busbars, and the test loop comprises a fault current limiting resistor, the limiting fault current resistance The first end of the device is connected to the busbar through a fuse element, and a scribing device is slidably arranged on the fault current limiting resistor, and is connected to the corresponding fault current detection point through the scribing device;

The other side of the insulating plate is provided with several columns of connection end groups, each connection end group includes at least two fixed ends for installing fuse elements, one of the fixed ends is connected to the busbar, and the other fixed end is connected to the The first end is connected.

2 . The fault current detection device according to claim 1 , wherein the number of the test loops is not less than 6. 3 .

3 . The fault current detection device according to claim 1 , wherein the scribing device is a scriber, comprising a moving body and a connecting line, and the moving body can slide and stop on the fault current resistor. 4 . Any position on the moving body is used to adjust the size of the fault current limiting resistor, and a connecting line is provided on the moving body, and the connecting line is connected to the corresponding fault current detection point.

4 . The fault current detection device according to claim 1 , wherein the fault current detection points comprise a plurality of points, which correspond to the test loops one-to-one. 5 .

5 . The fault current detection device according to claim 1 , further comprising a support, and the insulating plate is arranged on the support. 6 .

6 . The fault current detection device according to claim 1 , wherein the fault current limiting resistor is arranged on the insulating plate through two fixed ends. 7 .

7 . The fault current detection device according to claim 1 , wherein the fault current limiting resistor comprises four resistance wires, and the resistance wires are spirally wound together in the same direction and around the same center line, 8 . The resistance wires are in close contact, so that the resistors are distributed in a straight line as a whole.

8 . The fault current detection device of claim 7 , wherein the resistance wire is made of an alloy material, or further, a Cr30Ni70 alloy. 9 .

9 . The fault current detection device according to claim 7 , wherein the wire diameter of the resistance wire is 0.8-1.0 mm. 10 .

10 . The fault current detection device according to claim 7 , wherein the inclination angle between the resistance wire and the center line is 30°-60°. 11 .