CN111521930A - Fault current limiting resistor and fault current detection device - Google Patents

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

A fault current limiting resistor and fault current detection device

technical field

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

Background technique

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

Low-voltage switchgear and control equipment usually include circuit breakers, low-voltage switches, isolators, isolating switches, fuse combinations, contactors, motor starters, terminal blocks, automatic transfer switches, etc. It is mainly used for making and breaking circuits whose rated voltage AC does not exceed 1000V or DC does not exceed 1500V.

GB/T 14048.1-2012 "Low-voltage switchgear and control equipment - Part 1: General" is the national standard for this type of product. The standard specifies all the rules and requirements for the basic performance of various low-voltage switchgear and control equipment. Making and breaking capacity, short-circuit making and breaking capacity are the test items that must be carried out in the inspection of various low-voltage switchgear and control equipment products, while the making and breaking capacity test and the performance test under short-circuit conditions all need to detect the fault current .

The detection circuit of fault current, as specified in the standard, consists of two parts: fuse element and fault current limiting resistor. The fuse element adopts a copper wire with a certain diameter and a length of at least 50mm or an equivalent fuse link. Its diameters correspond one-to-one according to the expected fault current, as shown in the following table:

Comparison table of copper wire diameter of fuse element and expected fault current

Copper wire diameter (mm) Expected fault current in fuse element circuit (A) 0.1 50 0.2 150 0.3 300 0.4 500 0.5 800 0.8 1500

The standard points out that when a copper wire with a diameter of Φ0.8mm passes a current of 1500A with a frequency between 45Hz and 67Hz, it will melt in about half a cycle (or about 0.01s for DC).

The material specification and technical requirements of the fault current limiting resistor are not clearly indicated in the standard, but according to the function of the fault current detection circuit, it is not difficult to know that when the fault current limiting resistor passes a current of 1500A with a frequency between 45Hz and 67Hz, At least it should be blown later than the fuse element, and the fault current should be limited to within 1500 (1 ± 10%) A (or within the range of other levels of fault current).

Generally, the rated voltages of low-voltage switchgear and control equipment are most commonly 400V and 690V. Taking the rated voltage level of 400V as an example, the voltage loaded on the fault detection circuit is 230V. When the fault current is 1500A, the instantaneous power requirement of the fault detection circuit will exceed 345kW, and the size of its limiting fault current resistance is only 150mΩ or less.

According to the inventor's knowledge, the commonly used high-power resistors on the market at present can only withstand about tens of watts, at most hundreds of watts, in the size of 150mΩ. Moreover, the volume of a single resistor is also large, and the higher the power requirement, the larger the volume, and the more difficult it is to achieve variable resistance. To meet the test requirements, complex series-parallel connections must be made using a large number of commonly used high-power resistors. This greatly limits the convenience of such resistors and greatly increases their cost. Moreover, each test requires at least 6 or more fault detection circuits. Therefore, the fault current limiting resistor made of commonly used high-power resistors will be extremely bulky, expensive, and difficult to adjust the size of the resistance, resulting in extremely poor operability.

SUMMARY OF THE INVENTION

In order to solve the above problems, the present disclosure proposes a fault current limiting resistor and a fault current detection device. The fault current limiting resistor provided by the present disclosure has a fuse time of 2 cycles under a current of 1500A, which is only longer than the fuse element using copper The wire lasts one and a half cycles, which can meet the requirement that the fuse element is blown first. At the same time, the fault current detection device can realize the detection of multiple fault currents, and can support tests under different fault currents.

According to some embodiments, the present disclosure adopts the following technical solutions:

First of all, the present disclosure provides a fault current limiting resistor, which includes four resistance wires, which are spirally wound together in the same direction and around the same center line, and the resistance wires are in close contact, so that the resistor as a whole is in the same shape. straight line distribution.

As an optional embodiment, the resistance wire is made of alloy material, and Cr30Ni70 alloy is selected.

As an optional embodiment, the wire diameter of the resistance wire is 0.8-1.0 mm. As an optional embodiment, the inclination angle of the resistance wire and the center line is 30°-60°.

Secondly, the present disclosure provides a fault current detection device, including an insulating plate, a plurality of rows of test circuits and bus bars are arranged on one side of the insulating plate, and the test circuit includes the above-mentioned fault current limiting resistor, the limiting The first end of the fault current resistor 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.

As an optional embodiment, the number of the test loops is not less than 6.

As an optional embodiment, the scribing device is a scribing device, including a moving body and a connecting line, and the moving body can slide and stop at any position on the fault current resistor for convenient adjustment of the fault current limiting resistor The size of the moving body is provided with a connecting line, and the connecting line is connected to the corresponding fault current detection point.

As an optional implementation manner, the fault current detection points include multiple ones, which correspond to the test loops one-to-one.

As an optional embodiment, a bracket is also included, and the insulating plate is arranged on the bracket.

As an optional embodiment, the fault current limiting resistor is provided on the insulating plate through two fixed ends.

Compared with the prior art, the beneficial effects of the present disclosure are:

The material of the resistance wire used in the present disclosure for making the fault current limiting resistor is an alloy, and the cost is low. The fault current limiting resistor is straight in shape, resulting in minimal inductance. Under the current of 1500A, the fusing time is 2 cycles, which is only one and a half cycles later than the copper wire used for the fuse element, which meets the requirement that the fuse element fuses first.

The fault current limiting resistor provided by the present disclosure is small in size, simple in manufacture, and low in cost, and through a simple scribing device, the size of the resistance can be easily adjusted, and it is used to support tests under different fault currents.

The present disclosure can simultaneously realize multi-channel fault current detection, is simple and practical, and has high test efficiency.

Description of drawings

The accompanying drawings that constitute a part of the present disclosure are used to provide further understanding of the present disclosure, and the exemplary embodiments of the present disclosure and their descriptions are used to explain the present disclosure and do not constitute an improper limitation of the present disclosure.

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

FIG. 2 is a schematic view of the structure of the A surface of the fault current detection device of the present disclosure;

FIG. 3 is a schematic view of the B-side structure of the fault current detection device of the present disclosure;

Among them: 1. Bus bar, 2. Connection end A, 3. Fault current limiting resistor, 4. Scribing device, 5. Connecting wire, 6. Connection end B, 7, bracket, 8, Connection end C, 9 , Connection end D, 10, fuse element, 11, insulating plate.

Detailed ways:

The present disclosure will be further described below with reference to the accompanying drawings and embodiments.

It should be noted that the following detailed description is exemplary and intended to provide further explanation of the present disclosure. Unless otherwise defined, 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 should be noted that the terminology used herein is for the purpose of describing specific embodiments only, and is not intended to limit the exemplary embodiments according to the present disclosure. As used herein, unless the context clearly dictates otherwise, the singular is intended to include the plural as well, furthermore, it is to be understood that when the terms "comprising" and/or "including" are used in this specification, it indicates that There are features, steps, operations, devices, components and/or combinations thereof.

In this disclosure, terms such as "upper", "lower", "left", "right", "front", "rear", "vertical", "horizontal", "side", "bottom", etc. The orientation or positional relationship is based on the orientation or positional relationship shown in the drawings, and is only a relational word determined for the convenience of describing the structural relationship of each component or element of the present disclosure, and does not specifically refer to any component or element in the present disclosure, and should not be construed as a reference to the present disclosure. public restrictions.

In the present disclosure, terms such as "fixed connection", "connected", "connected", etc. should be understood in a broad sense, indicating that it may be a fixed connection, an integral connection or a detachable connection; it may be directly connected, or through an intermediate connection. media are indirectly connected. For the relevant scientific research or technical personnel in the field, the specific meanings of the above terms in the present disclosure can be determined according to specific situations, and should not be construed as limitations on the present disclosure.

As shown in Figure 1, the fault current limiting resistor, in this embodiment, the selected resistance wire material is: Cr30Ni70 alloy, the wire diameter is 0.90mm, the weight per meter is 0.005153kg/m, and the resistance per meter is 1.855Ω/m (20 ℃ Time).

The winding method of the fault current limiting resistor is that four resistance wires are tightly wound at the same time, and there is no large gap in the middle of the resistance wires.

The winding completed resistors are arranged in a straight line to avoid inductive reactance caused by the spiral arrangement, resulting in the overall resistance value being greater than the pre-test measured value.

As shown in FIG. 2, a fault current detection device includes a bracket 7 and an insulating plate 11 arranged thereon. One side of the insulating plate 11 is provided with a plurality of rows of test circuits and bus bars 1, and the test circuits all include limit faults. The current resistor 3, the two ends of the fault current limiting resistor 3 are respectively fixed on the two connection ends. The first end of the fault current limiting resistor 3 is wound or fixed on the connection end A2 and is connected to the bus bar 1 through the fuse element 10 . During the test, in each fault current detection circuit, the connection terminal A2 of the fault current limiting resistor is connected to the busbar 1 through a wire. Then, the bus bar 1 is connected to the test circuit neutral point or artificial neutral point. To realize the simultaneous detection of multiple fault currents in the test.

The bracket 7 includes a base, and a support frame arranged on the base, and the support frame includes two, which are located on both sides of the insulating plate 11 respectively.

A scribing device 4 is slidably provided on the fault current limiting resistor 3, and is connected to the connection end B6 through the scribing device 4, and the connection end B6 is connected to the corresponding fault current detection point;

As shown in FIG. 3 , the other side of the insulating plate is provided with several columns of connection end groups, and each connection end group includes at least two fixed ends (ie, the connection end C8 and the connection end D9, wherein the connection end D9 is connected to the fault current limiting resistor) One fixed point connection end A2 is connected together), a fuse element 10 is installed between the connection end C8 and the connection end D9, wherein the connection end C8 is connected with the bus bar 1, and the connection end D9 is connected with the connection end A2.

In this embodiment, the fuse element 10 is a copper wire, and in each test, fuse elements with different diameters can be replaced according to requirements.

The insulating plate 11 may be an epoxy resin insulating plate.

During the test, in each fault current detection circuit, the current flowing through the route is: the fault current detection point of the test sample, the connecting terminal B 6, the connecting wire 5, the marking device 4, the fault current limiting resistor 3, the connecting terminal A 2 ( That is, the connection terminal D 9), the fuse element 10, the connection terminal C8, the busbar 1, the test voltage neutral point or the artificial neutral point.

The above fault detection device has the advantages of small size, simple manufacture and low cost of the fault current limiting resistor, and through a simple scribing device, the size of the resistance can be easily adjusted, which is used to support tests under different fault currents.

Due to the small size of the fault current limiting resistor, 6 or even more fault current detections can be easily realized.

The resistance wire material used to make the fault current limiting resistor is generally used to make the electric furnace, which is relatively common and the cost is very low.

Its fault current limiting resistor is linear in shape, resulting in minimal inductance.

Its fault current limiting resistor, under the current of 1500A, has a fuse time of 2 cycles, which is only 1 and a half cycles later than the copper wire used for the fuse element, which just meets the requirement that the fuse element fuses first. Suitable for low-voltage switchgear and control equipment testing.

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

Although the specific embodiments of the present disclosure have been described above in conjunction with the accompanying drawings, they do not limit the protection scope of the present disclosure. Those skilled in the art should understand that on the basis of the technical solutions of the present disclosure, those skilled in the art do not need to pay creative efforts. Various modifications or variations that can be made are still within the protection scope of the present disclosure.

Claims (10)

1. A fault current limiting resistor, characterized by: the resistance wires are spirally wound together along the same direction and around the same central line, and the resistance wires are in close contact with each other, so that the whole resistor is linearly distributed.

2. A fault current limiting resistor as claimed in claim 1, wherein: the resistance wire is made of alloy materials, or further made of Cr30Ni70 alloy.

3. A fault current limiting resistor as claimed in claim 1, wherein: the wire diameter of the resistance wire is 0.8-1.0 mm.

4. A fault current limiting resistor as claimed in claim 1, wherein: the inclination angle of the resistance wire and the center line is 30-60 degrees.

5. A fault current detection device is characterized in that: the device comprises an insulating plate, wherein a plurality of rows of test circuits and bus bars are arranged on one surface of the insulating plate, each test circuit comprises the fault current limiting resistor as claimed in any one of claims 1 to 4, 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 connected to a corresponding fault current detection point 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.

6. The fault current detection device as claimed in claim 5, wherein: the number of the test loops is not less than 6.

7. The fault current detection device as claimed in claim 5, wherein: the scribing device is a scriber and comprises a moving body and a connecting line, wherein the moving body is capable of sliding and stopping at any position on the fault current resistor and is used for adjusting and limiting the size of the fault current resistor, the moving body is provided with the connecting line, and the connecting line is connected with the corresponding fault current detection point.

8. The fault current detection device as claimed in claim 5, wherein: the fault current detection points comprise a plurality of detection points which are in one-to-one correspondence with the test loops.

9. The fault current detection device as claimed in claim 5, wherein: the insulation board is arranged on the support.

10. The fault current detection device as claimed in claim 5, wherein: the fault current limiting resistor is disposed on the insulating plate through two fixed ends.

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