Power supply system for electric heater of heating furnace

Abstract

The invention discloses a power supply system for an electric heater of a heating furnace, the electric heater comprises a first phase junction box, a second phase junction box and a third phase junction box which are independent, the power supply system comprises a power regulation cabinet and a split-phase transfer box, and power is transmitted from the power regulation cabinet to the split-phase transfer box through a three-core cable; the split-phase transfer box is close to the second phase junction box; the split-phase transfer box is respectively connected with the first phase junction box, the second phase junction box and the third phase junction box through 2N single-core cables, and N is a natural number. In the scheme of the invention, the three-core cable is adopted for power transmission from the power regulation cabinet to the split-phase transfer box in a long distance, so that the influence of eddy current caused by unbalanced three-phase current or improper arrangement when a single-core cable is adopted in a long distance can be obviously reduced, and the cable laying cost is saved; the three-core cable is converted into the single-core cable through the split-phase conversion box, split-phase power supply of the heater is met, mutual offsetting of magnetic fields is achieved through the arrangement mode of the single-core cable, and the eddy current loss influence is reduced.

Description

Technical Field

[0001] The present invention relates to the technical field of electric heaters, and particularly to a power supply system for an electric heater of a heating furnace. Background Art

[0002] High-power electric heaters are widely used in heating furnaces in fields such as petrochemical and metallurgy. Low-temperature fluid media pass through specific heat exchange channels inside the heating furnace, and through a path designed based on the principles of fluid thermodynamics, the temperature of the gas entering the heating furnace is increased, and finally high-temperature gas meeting the process requirements is obtained.

[0003] There is a heating furnace widely existing in fields such as petrochemical and metallurgy, which has a cylindrical structure. Each phase of the internal heater is composed of multiple groups of heating elements. The power supply ends of the heater are three independent junction boxes, namely, phase A, phase B, and phase C. And the three junction boxes are distributed on the outer side of the heating furnace at an interval of 120°. Generally, the power supply to the high-power heater is realized by means of a multi-tap transformer combined with a laminated power supply cabinet voltage regulation method.

[0004] At present, high-power electric heaters (such as 6MW level) need to be powered by separate phases to meet high current (single-phase current reaches 1600A), and single-core cables are used. Not only the cost is high, but also unbalanced three-phase currents or improper arrangement of single-core cables will cause eddy currents in the metal sheath / armoring layer, leading to local overheating, insulation aging, and even short-circuit risks. The temperature rise of long-distance single-core cables is significant, reducing the service life. Summary of the Invention

[0005] The purpose of the present invention is to provide a power supply system for an electric heater of a heating furnace to at least partially solve the above problems of the prior art.

[0006] To achieve the above purpose, the present invention provides a power supply system for an electric heater of a heating furnace. The electric heater includes three independent junction boxes, namely, a first phase, a second phase, and a third phase. The three independent junction boxes are spaced apart from each other and distributed on the outer side of the heating furnace;

[0007] The power supply system includes a power regulation cabinet and a phase separation transfer box;

[0008] The power regulation cabinet and the phase separation transfer box are powered by a three-core cable;

[0009] The phase separation transfer box is respectively connected to the first-phase junction box, the second-phase junction box, and the third-phase junction box through 2N single-core cables, where N is a natural number;

[0010] Wherein, the phase separation transfer box is arranged on the outer side of the heating furnace, close to the second-phase junction box;

[0011] A support is provided outside the phase - splitting transfer box on the outside of the heating furnace. The support is used to support and space apart the single - core cables of the first phase, the second phase, and the third phase in a triangular pattern.

[0012] Among them, N cables of the second phase are directly connected to the second - phase junction box, and the remaining cables of the second phase are wound around the heating furnace in a clockwise direction for one circle and then connected to the second - phase junction box.

[0013] N cables of the first phase are wound around the heating furnace for one - third of a circle in a clockwise direction and then connected to the first - phase junction box, and the remaining cables of the first phase are wound around the heating furnace for two - thirds of a circle in a counter - clockwise direction and then connected to the first - phase junction box.

[0014] N cables of the third phase are wound around the heating furnace for two - thirds of a circle in a clockwise direction and then connected to the third - phase junction box, and the remaining cables of the third phase are wound around the heating furnace for one - third of a circle in a counter - clockwise direction and then connected to the third - phase junction box.

[0015] Preferably, multiple groups of supports are provided outside the phase - splitting transfer box, and each group of supports is used to support one single - core cable of the first phase, the second phase, and the third phase.

[0016] Preferably, N is equal to 2.

[0017] Preferably, the maximum working current of each phase is 1600A, and the three - core cable includes 4 YJV22 - 3×300mm 2 three - core cables.

[0018] Preferably, each phase of the cable led out from the phase - splitting transfer box includes 4 YJV82 - 1×240mm 2 single - core cables.

[0019] Preferably, the phase - splitting transfer box includes four three - core cable inlets and four groups of single - core cable outlets. Each group of single - core cable outlets includes three single - core cable outlets arranged in a triangular pattern. The 4 three - core cables are connected to the phase - splitting transfer box through the four three - core cable inlets, and are transferred into 4 groups of single - core cables. Each group of single - core cables includes 3 single - core cables and is output through a group of single - core cable outlets.

[0020] Preferably, the inside of the phase - splitting transfer box includes supports for keeping the 3 single - core cables of each group of single - core cables spaced apart in a triangular pattern inside the phase - splitting transfer box.

[0021] Preferably, the phase - splitting transfer box includes the metal sheath of the three - core cable, the grounding copper bar, the surge protector, the fuse, the conversion copper bar, the shielding layer of the single - core cable, and the insulating terminal of the single - core cable.

[0022] Preferably, the distance between adjacent - phase single - core cables is not less than 2 times the outer diameter of the single - core cable.

[0023] Preferably, the cable spacing between adjacent phases is equal.

[0024] Preferably, the three independent junction boxes are evenly distributed on the outer side of the heating furnace at intervals of 120 degrees from each other.

[0025] Preferably, the system further includes: a medium-voltage switchgear cabinet, a multi-tap transformer electrically connected to the medium-voltage switchgear cabinet, and the multi-tap transformer is electrically connected to the power regulation cabinet.

[0026] Compared with the prior art, the present invention has at least the following advantages:

[0027] For the long-distance power transmission from the power regulation cabinet to the phase-splitting transfer box, three-core cables are used, which can significantly reduce the influence of eddy currents generated by unbalanced three-phase currents or improper arrangement when using single-core cables over long distances, and also save the cable laying cost; the three-core cable is converted into a single-core cable through the phase-splitting conversion box to meet the phase-splitting power supply of the heater. The single-core cables after phase-splitting are laid along different winding paths and arranged in a triangular pattern, ensuring that the magnetic fields of the three single-core cables arranged in a triangular pattern are evenly cancelled out in space, reducing the influence of eddy current loss and electromagnetic interference on adjacent communication lines or temperature sensors. At the same time, the spacing between single-core cables is 2 times the outer diameter of the cable, achieving a balance between cable heat dissipation and electromagnetic compatibility. Description of the Drawings

[0028] Figure 1 It is a schematic structural diagram of a power supply system for an electric heater of a heating furnace provided in Embodiment 1 of the present invention.

[0029] Figure 2 It is a schematic cross-sectional view of the cable along any vertical direction of the center of the heating furnace in the power supply system provided in Embodiment 1 of the present invention.

[0030] Figure 3 It is a schematic internal structure diagram of the phase-splitting transfer box included in the power supply system provided in Embodiment 1 of the present invention.

[0031] Figure 4 It is a schematic connection diagram of the phase-splitting transfer box of the power supply system provided in Embodiment 1 of the present invention with the A-phase, B-phase, and C-phase junction boxes outside the heating furnace.

[0032] Figure 5 It is a schematic diagram of the incoming and outgoing line structure of the phase-splitting transfer box included in the power supply system provided in Embodiment 2 of the present invention. Detailed Embodiments

[0033] To enable those skilled in the art to better understand the solution of the present invention, the technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all of the embodiments. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present invention without making creative efforts shall fall within the scope of protection of the present invention.

[0034] It should be noted that the terms "first", "second", etc. in the specification and claims of the present invention and the above-mentioned drawings are used to distinguish similar objects, and do not have to be used to describe a specific order or sequence. It should be understood that such data can be interchanged under appropriate circumstances to facilitate understanding of the embodiments of the present invention described herein. In addition, the terms "comprising" and "having" and any variations thereof are intended to cover non-exclusive inclusion. For example, a product or device comprising a series of units does not necessarily have to be limited to those units clearly listed, but may include other units not clearly listed or inherent to these products or devices.

[0035] In the present invention, the orientation or positional relationship indicated by the terms "upper", "lower", "left", "right", "front", "rear", "top", "bottom", "inner", "outer", "middle", "vertical", "horizontal", "lateral", "longitudinal", etc. is based on the orientation or positional relationship shown in the drawings. These terms are mainly used to better describe the present invention and its embodiments, and are not used to limit that the indicated devices, elements or components must have a specific orientation or be constructed and operated in a specific orientation.

[0036] Moreover, in addition to being able to represent an orientation or positional relationship, some of the above terms may also be used to represent other meanings. For example, the term "upper" may also be used to represent a certain attachment relationship or connection relationship in some cases. For those of ordinary skill in the art, the specific meanings of these terms in the present invention can be understood according to specific circumstances.

[0037] In addition, the terms "mounted", "set", "provided with", "connected", "connected to", "socketed" should be understood in a broad sense. For example, it can be a fixed connection, a detachable connection, or an integral structure; it can be a mechanical connection or an electrical connection; it can be directly connected, or indirectly connected through an intermediate medium, or there can be internal communication between two devices, elements or components. For those of ordinary skill in the art, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0038] It should be noted that, without conflict, the embodiments in the present invention and the features in the embodiments can be combined with each other. The present invention will be described in detail below with reference to the drawings and in conjunction with the embodiments.

[0039] Example 1

[0040] This example discloses a power supply system for the electric heater of a heating furnace. Figure 1 The structural schematic diagram of this power supply system is shown. Figure 2 It is a schematic cross-sectional view of any vertical direction along the center of the heating furnace of the power supply system provided in Example 1 of the present invention. Figure 3 The internal structural schematic diagram of the phase-splitting transfer box included in this power supply system is shown.

[0041] Refer to Figure 1 As shown, this system includes a power regulation cabinet 400 and a phase-splitting transfer box 500. The electric heater 600 includes three independent junction boxes for the first phase, the second phase, and the third phase, and the three independent junction boxes are spaced apart from each other on the outer side of the heating furnace. The first phase, the second phase, and the third phase are respectively one of the A phase, the B phase, and the C phase, and are different from each other.

[0042] This power supply system may further include: a medium-voltage switchgear 200 and a multi-tap transformer 300 electrically connected to the medium-voltage switchgear. The multi-tap transformer 300 is electrically connected to the power regulation cabinet 400. The medium-voltage switchgear 200 is electrically connected to a three-phase power supply 100.

[0043] In a preferred embodiment, the three independent junction boxes are evenly distributed at intervals of 120 degrees on the outer side of the heating furnace.

[0044] Among them, the power regulation cabinet 400 and the phase-splitting transfer box 500 transmit power through a three-core cable;

[0045] The phase-splitting transfer box 500 is respectively connected to the first-phase junction box, the second-phase junction box, and the third-phase junction box through 2N single-core cables, where N is a natural number, for example, N is 2 or 3.

[0046] Among them, the phase-splitting transfer box 500 is arranged on the outer side of the heating furnace, close to the second-phase junction box;

[0047] A bracket is arranged outside the phase-splitting transfer box 500, and the bracket is used to support and space apart the single-core cables of the first phase, the second phase, and the third phase in a triangular shape;

[0048] The N cables of the second phase are directly connected to the second-phase junction box, and the remaining cables of the second phase are connected to the second-phase junction box after winding around the heating furnace in a clockwise direction for one circle;

[0049] The N cables of the first phase are connected to the first-phase junction box after winding around the heating furnace for one-third of a circle in a clockwise direction, and the remaining cables of the first phase are connected to the first-phase junction box after winding around the heating furnace for two-thirds of a circle in a counterclockwise direction;

[0050] The N cables of the third phase are connected to the third-phase junction box after winding two-thirds of a circle around the heating furnace in the clockwise direction, and the remaining cables of the third phase are connected to the third-phase junction box after winding one-third of a circle around the heating furnace in the counterclockwise direction.

[0051] Among them, the second-phase junction box can be phase A, phase B, or phase C.

[0052] In a preferred embodiment, multiple groups of brackets are provided outside the phase-splitting transfer box, and each group of brackets is used to support one single-core cable of the first phase, the second phase, and the third phase.

[0053] In a preferred embodiment, the distance between adjacent single-core cables is not less than twice the outer diameter of the single-core cable. Moreover, the distances between the cables of adjacent phases can be equal, that is, the distances between the cable of the middle phase and the cables of the upper and lower phases or the left and right phases are equal, and the distances are all not less than twice the outer diameter of the single-core cable.

[0054] Among them, each group of brackets can include multiple brackets spaced apart from each other, as long as it is ensured that the minimum distance between adjacent single-core cables is not less than twice the outer diameter of the single-core cable. Each group of brackets can also only include a circular bracket surrounding the heating furnace, and the three cables of phase A, phase B, and phase C are laid on this circular bracket to form a triangular arrangement.

[0055] As Figure 2 shown, the heating furnace and the cables laid outside the heating furnace are vertically cut along any vertical plane passing through the center of the heating furnace, and multiple three-phase cables arranged in a triangular pattern are obtained. Among them, 10 represents the phase A cable, 11 represents the phase B cable, and 12 represents the phase C cable. 13 and 14 are non-magnetic clamps on the bracket for clamping the cables, for example, made of stainless steel or aluminum alloy.

[0056] Figure 2 shows two groups of brackets 01 and 02. The two bracket sections close to the heating furnace belong to one group of brackets 01, and the two bracket sections on the left and right sides far from the heating furnace belong to another group of brackets 02. Among them, each group of brackets is used to support three single-core cables. It is easy to understand that Figure 2 is only an example here. When each phase includes more than 4 single-core cables, there can be more groups of brackets.

[0057] In a preferred embodiment, referring to Figure 3 shown, the phase-splitting transfer box 500 includes the metal sheath 15 of the three-core cable, the grounding copper bar 17, the surge protector 18, the fuse 19, the three-core cable aggregation copper bar 20, the three-phase connection copper bar 21, the conversion copper bar 22, the single-core cable 23, the insulation terminal 24 of the single-core cable, and the shielding layer 25 of the single-core cable.

[0058] For long-distance power transmission from the power regulation cabinet to the phase-separated connection box, three-core cables are used, which can significantly reduce the influence of eddy currents caused by unbalanced three-phase currents or improper arrangement when using single-core cables over long distances, and also save the cost of cable laying. The three-core cable is converted into a single-core cable through the phase-separated conversion box to meet the phase-separated power supply of the heater. The single-core cables after phase separation are laid along different winding paths and arranged in a triangular pattern to ensure that the magnetic fields of the three single-core cables arranged in a triangular pattern are evenly cancelled out in space, reducing the influence of eddy current loss and electromagnetic interference on adjacent communication lines or temperature sensors. At the same time, the distance between single-core cables is 2 times the outer diameter of the cable to achieve a balance between cable heat dissipation and electromagnetic compatibility.

[0059] Embodiment 2

[0060] Embodiment 2 of the present invention provides a power supply system for the electric heater of a heating furnace, referring to Figure 1 As shown, the system includes a medium-voltage switchgear 200, a multi-tap transformer 300, a power regulation cabinet 400, a phase-separated connection box 500, and an electric heater 600. Among them, the medium-voltage switchgear 200 is electrically connected to the three-phase power supply 100; the multi-tap transformer 300 is electrically connected to the medium-voltage switchgear 200 and the power regulation cabinet 400, and the power regulation cabinet 400 and the phase-separated connection box 500 are connected by a three-core cable for power transmission.

[0061] Among them, the three-phase power supply 100 is, for example, an HV1 power supply, such as a 10 kV, 50 Hz power supply for power. The medium-voltage switchgear 200 may include a circuit breaker QF1, with a rated voltage and current of, for example, 10 kV and 630 A. The multi-tap transformer 300 is adapted to the power supply, and can also work at a voltage of 10 kV, for example. The power regulation cabinet can adjust the input power of the electric heater. For example, it can be set to four gears of adjustment: Ue = 2450 V, Ie = 1600 A; Ue = 2083 V, Ie = 1500 A; Ue = 1770 V, le = 1200 A; Ue = 1505 V, Ie = 1000 A.

[0062] The power regulation cabinet 400 and the phase-separated connection box 500 are connected by a three-core cable for power transmission; the phase-separated connection box 500 is close to the second-phase junction box;

[0063] The phase-separated connection box 500 respectively leads out three-phase cables and connects them to the first-phase junction box, the second-phase junction box, and the third-phase junction box; each phase cable includes 2N single-core cables;

[0064] A bracket is provided outside the phase-separated connection box 500 to support and space the single-core cables of the first phase, the second phase, and the third phase in a triangular pattern;

[0065] Among them, N cables of the second phase are directly connected to the second-phase junction box, and the remaining cables of the second phase are connected to the second-phase junction box after winding around the heating furnace in a clockwise direction;

[0066] The N cables of the first phase are wound around one-third of the heating furnace in the clockwise direction and then connected to the first-phase junction box, and the remaining cables of the first phase are wound around two-thirds of the heating furnace in the counterclockwise direction and then connected to the first-phase junction box;

[0067] The N cables of the third phase are wound around two-thirds of the heating furnace in the clockwise direction and then connected to the third-phase junction box, and the remaining cables of the third phase are wound around one-third of the heating furnace in the counterclockwise direction and then connected to the third-phase junction box.

[0068] In a preferred embodiment, N is equal to 2. That is, the phase-splitting transfer box is connected to the first-phase junction box, the second-phase junction box, and the third-phase junction box respectively through 4 single-core cables.

[0069] Taking the heater power of 6 MW as an example, the maximum working current of each phase is 1600 A. Under the conditions of meeting the cable current-carrying capacity and voltage drop, for a long distance (about 200 meters), 4 YJV22-3×300mm 2 three-core cables are first selected for spliced power supply; near the phase-splitting transfer box, the above three-core cables are then converted into 4 YJV82-1×240mm 2 single-core cables for spliced power supply through the phase-splitting transfer box.

[0070] Among them, the YJV22-3×300mm 2 three-core cable is a commonly used armored power cable, suitable for three-phase high-power power transmission or distribution systems. YJ represents cross-linked polyethylene insulation (XLPE), V represents polyvinyl chloride (PVC) sheath, 22 represents steel tape armor + PVC outer sheath, 3×300mm 2 The 3 in it represents three cores, corresponding to three phases (A / B / C phases), and 300mm 2 represents the cross-sectional area of each core conductor. In the YJV82-1×240mm2 single-core cable, YJ represents cross-linked polyethylene insulation, V represents polyvinyl chloride (PVC) sheath, 8 represents aluminum alloy tape armor, 2 represents polyvinyl chloride outer sheath, and 1×240mm 2 represents single core and the cross-sectional area of the conductor is 240 square millimeters.

[0071] In this embodiment, taking the phase-splitting transfer box 500 close to the B phase as an example, 4 single-core cables of each of the A phase, B phase, and C phase are led out from the phase-splitting transfer box 500. The 4 single-core cables of each phase are divided into the first group and the second group, with 2 single-core cables in one group. Figure 4Taking the laying of the first group of 2 single-core cables of each phase as an example for illustration. The 2 single-core cables of the first group of cables 1 of phase A are divided into cables 4 and 5, the 2 single-core cables of the first group of cables 2 of phase B are divided into cables 6 and 7, and the 2 single-core cables of the first group of cables 3 of phase C are divided into cables 8 and 9. The single-core cable 7 in phase B is directly connected to the phase B junction box, and the other single-core cable 6 is connected to the phase B junction box after winding around the heating furnace in a clockwise direction; one cable 4 in phase A is connected to the phase A junction box after winding around the heating furnace one-third of a circle in a clockwise direction, and the other single-core cable 5 is connected to the phase A junction box after winding around the heating furnace two-thirds of a circle in a counterclockwise direction; one cable 8 in phase C is connected to the phase C junction box after winding around the heating furnace two-thirds of a circle in a clockwise direction, and the other single-core cable 9 is connected to the phase C junction box after winding around the heating furnace one-third of a circle in a counterclockwise direction. It is easy to understand that the second group of 2 single-core cables of each phase adopts the same winding method as the first group of 2 single-core cables. Moreover, after the laying of the 2 single-core cables of each group of each phase is completed, their cross-sections form Figure 2 the triangular arrangement shown.

[0072] In a preferred embodiment, referring to Figure 5 shown, it shows a schematic diagram of the incoming and outgoing line structure of the phase-separated transfer box included in the power supply system provided in Embodiment 2 of the present invention. The incoming and outgoing line ports 27 of the phase-separated transfer box 500 include four three-core cable inlets and four groups of single-core cable outlets, and each group of single-core cable outlets includes three single-core cable outlets arranged in a triangular shape; 4 three-core cables are connected to the phase-separated transfer box through 4 three-core cable inlets, for example, connected to the three-core cable aggregation copper bar 20; each phase cable led out from the phase-separated transfer box (for example, the conversion copper bar 22) includes 4 single-core cables, which are divided into 4 groups of single-core cables, and each group of single-core cables includes 1 single-core cable of each of the 3 phases and is output through a group of single-core cable outlets, that is, through four groups of single-core cable outlets, and are respectively connected to the phase A, phase B, and phase C junction boxes. In a preferred embodiment, the phase-separated transfer box 500 includes supports for keeping the 3 single-core cables of each group of single-core cables spaced apart in a triangular shape inside the phase-separated transfer box.

[0073] By adopting the solution provided by the present invention, three-core cables are used for long-distance power transmission from the power regulation cabinet to the phase-separated transfer box, which can significantly reduce the influence of eddy currents generated by unbalanced three-phase currents or improper arrangement when using single-core cables over a long distance, and save the cable laying cost; the three-core cables are converted into single-core cables through the phase-separated conversion box to meet the phase-separated power supply of the heater. The single-core cables after phase separation are laid according to different winding paths and arranged in a triangular shape, ensuring that the magnetic fields of the three single-core cables arranged in a triangular shape are evenly cancelled out in space, reducing the influence of eddy current loss and electromagnetic interference on adjacent communication lines or temperature sensors. At the same time, the distance between single-core cables is 2 times the outer diameter of the cable, realizing the balance between cable heat dissipation and electromagnetic compatibility.

[0074] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit it. Those of ordinary skill in the art should understand that the technical solutions described in the foregoing embodiments can be modified, or some of the technical features can be equivalently replaced; these modifications or replacements do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

1. A power supply system for an electric heater of a heating furnace, wherein the electric heater includes three independent junction boxes for the first phase, the second phase, and the third phase, and the three independent junction boxes are spaced apart from each other on the outer side of the heating furnace; characterized in that, the power supply system includes a power regulation cabinet and a phase-splitting transfer box; the power regulation cabinet and the phase-splitting transfer box are electrically connected by a three-core cable; the phase-splitting transfer box is connected to the first-phase junction box, the second-phase junction box, and the third-phase junction box respectively by 2N single-core cables, where N is a natural number; wherein, the phase-splitting transfer box is arranged on the outer side of the heating furnace, close to the second-phase junction box; a bracket is arranged on the outer side of the heating furnace outside the phase-splitting transfer box, and the bracket is used to support and space apart the single-core cables of the first phase, the second phase, and the third phase in a triangular arrangement; wherein, N cables of the second phase are directly connected to the second-phase junction box, and the remaining cables of the second phase are connected to the second-phase junction box after winding around the heating furnace in a clockwise direction for one circle; N cables of the first phase are connected to the first-phase junction box after winding around the heating furnace for one-third of a circle in a clockwise direction, and the remaining cables of the first phase are connected to the first-phase junction box after winding around the heating furnace for two-thirds of a circle in a counterclockwise direction; N cables of the third phase are connected to the third-phase junction box after winding around the heating furnace for two-thirds of a circle in a clockwise direction, and the remaining cables of the third phase are connected to the third-phase junction box after winding around the heating furnace for one-third of a circle in a counterclockwise direction.

2. The power supply system for the electric heater of the heating furnace according to claim 1, wherein, Multiple groups of brackets are arranged outside the phase-splitting transfer box, and each group of brackets is used to support one single-core cable of the first phase, the second phase, and the third phase.

3. The power supply system for the electric heater of the heating furnace according to claim 2, characterized in that, N equals 2, the maximum working current per phase is 1600 A, and the three-core cable includes 4 YJV22 - 3×300mm 2 three-core cables.

4. The power supply system for the electric heater of the heating furnace according to claim 3, characterized in that, Each phase cable led out from the phase-splitting transfer box includes 4 single-core cables of YJV82-1×240mm 2 ​ 5. The power supply system for the electric heater of the heating furnace according to claim 4, characterized in that, The phase-splitting transfer box includes four three-core cable inlets and four groups of single-core cable outlets, and each group of single-core cable outlets includes three single-core cable outlets arranged in a triangular pattern; the 4 three-core cables are connected to the phase-splitting transfer box through the four three-core cable inlets, and are transferred into 4 groups of single-core cables, and each group of single-core cables includes 3 single-core cables and is output through a group of single-core cable outlets.

6. The power supply system for the electric heater of the heating furnace according to claim 5, characterized in that, The phase-splitting transfer box includes supports for keeping the 3 single-core cables of each group of single-core cables spaced apart in a triangular pattern inside the phase-splitting transfer box.

7. The power supply system for the electric heater of the heating furnace according to any one of claims 1-6, characterized in that, The phase-splitting transfer box includes a metal sheath of the three-core cable, a grounding copper bar, a surge protector, a fuse, a conversion copper bar, a shielding layer of the single-core cable, and an insulating terminal of the single-core cable.

8. The power supply system for the electric heater of the heating furnace according to any one of claims 1-6, characterized in that, The distance between adjacent single-core cables is not less than 2 times the outer diameter of the single-core cable.

9. The power supply system for the electric heater of the heating furnace according to any one of claims 1-6, characterized in that, The three independent junction boxes are evenly distributed on the outer side of the heating furnace at intervals of 120 degrees.

10. The power supply system for the electric heater of the heating furnace according to any one of claims 1-6, characterized in that, It further includes: a medium-voltage switchgear cabinet, a multi-tap transformer electrically connected to the medium-voltage switchgear cabinet, and the multi-tap transformer is electrically connected to the power regulation cabinet.

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