Medium voltage dc ethylene propylene rubber insulated lszh flame retardant cable for ships

Abstract

The utility model discloses a medium -voltage direct current ethylene -propylene rubber insulation LSZH flame -retardant cable for warship, including multiple strandings tinned copper conductor, the conductor outer wrap first semiconductive tape, first semiconductive tape is equipped with three layer co -extrusion structure, from inside to outside is conductor shield layer, insulating layer and insulating shield layer. The conductor outer overlap wrap first semiconductive tape, adopt three layer co -extrusion extrusion process and extrude to avoid the impurity between layer and layer and influence the electrical property of product, three layer co -extrusion structure outer wrap second semiconductive tape prevents the damage of phase -to -phase shield to insulating wire core, and each insulating wire core is shielded with braided tinned copper wire, realizes phase -to -phase shield, homogenizes electric field, and after cabling, outer wrap high flame -retardant tape, and extrusion -coated thermosetting halogen -free low smoke flame -retardant polyolefin sheath, and the outer sheath irradiation crosslinking improves the mechanical physicality of material. The cable successfully passes through a plurality of rigorous electrical test, and the high reliability and insulating durability under the complex working condition such as load cycle, polarity reversal and operating overvoltage are verified.

Description

Technical Field

[0001] The utility model relates to the technical field of cables, specifically to a medium-voltage DC ethylene propylene rubber insulated LSZH flame-retardant cable for ships. Background Art

[0002] In recent years, the all-electric drive technology for ships has become a new focus of ship drive technology research by various countries. The all-electric drive technology for ships uses an electric drive device as the main power system. The basic principle is that the prime mover drives the generator, and the generator drives the motor set to drive the propeller to rotate. At present, the medium-voltage DC integrated electric propulsion technology for ships has become the most promising technology in the all-electric drive technology for ships due to its advantages such as high power density, high operating efficiency, and high operation flexibility. This technology system does not require a propulsion reduction gear device and an adjustable pitch propeller. While reducing the internal noise of the ship, it also makes the ship layout more flexible. At the same time, compared with the AC system, the DC system breaks through the frequency limit, reduces the requirements for the speed regulation characteristics of the prime mover, greatly reduces the volume and weight of the equipment, and effectively improves the system efficiency and power supply continuity, realizing a revolutionary transformation of the ship power system from the traditional mechanical method to the all-electric method.

[0003] In order to promote the implementation of the medium-voltage DC integrated electric propulsion system for ships and meet the comprehensive requirements of the medium-voltage DC integrated electric propulsion system for ships for high electrical performance, high shielding performance, high environmental adaptability, and safety of cables, a medium-voltage DC ethylene propylene rubber insulated halogen-free low-smoke (LSZH) flame-retardant cable for ships has been developed. Content of the Utility Model

[0004] Technical problems to be solved by the utility model: The purpose of the utility model is to solve the comprehensive requirements of the medium-voltage DC integrated electric propulsion system for ships for high electrical performance, high shielding performance, high environmental adaptability, and safety of cables, and to develop a medium-voltage DC ethylene propylene rubber insulated halogen-free low-smoke (LSZH) flame-retardant cable for ships.

[0005] Technical solution: To achieve the above purpose, the technical solution provided by the utility model is: a medium-voltage DC ethylene propylene rubber insulated LSZH flame-retardant cable for ships, including a multi-strand stranded tinned copper conductor, with a first semiconductive tape wrapped around the conductor, and a three-layer co-extrusion structure is provided outside the first semiconductive tape, which is successively a conductor shielding layer, an insulating layer, and an insulation shielding layer from inside to outside.

[0006] As a further improvement of the utility model, a second semiconductive tape is wrapped around the three-layer co-extrusion structure, and the overlap rate is ≥20%.

[0007] As a further improvement of the utility model, tinned copper wires are braided on the second semiconductive tape to form a braided shielding layer, and the braiding density is ≥80%, constituting a phase-separated shielding.

[0008] As a further improvement of the present utility model, the conductor shielding layer adopts a cross-linked semi-conductive rubber inner shielding material, with an extruded nominal thickness of 1.0 mm;

[0009] The insulating layer adopts natural color ethylene-propylene rubber, with an extruded nominal thickness of 2.5 mm. The average value of the insulating thickness ≥ the nominal thickness, the thickness at the thinnest part of the insulation ≥ 90% of the nominal thickness, and the concentricity ≤ 1.15;

[0010] The insulating shielding layer adopts a cross-linked peelable semi-conductive rubber outer shielding material, with an extruded nominal thickness of 0.8 mm.

[0011] As a further improvement of the present utility model, the conductor, the first semi-conductive tape, the three-layer co-extrusion structure, the second semi-conductive tape, and the braided shielding layer are right-twisted into an insulated wire core after stranding, and the stranding pitch-diameter ratio ≤ 15.

[0012] As a further improvement of the present utility model, a halogen-free low-smoke flame-retardant polypropylene rope is filled between the insulated wire cores during stranding.

[0013] As a further improvement of the present utility model, a highly flame-retardant tape is wrapped around after stranding.

[0014] As a further improvement of the present utility model, an outer sheath is extruded on the outermost layer. The outer sheath adopts an irradiated cross-linked polyolefin sheath material. The average value of the sheath thickness ≥ the nominal thickness, the thickness at the thinnest part ≥ 80% of the nominal thickness, and the maximum thickness of the sheath at any cross-section ≤ 1.66 times the minimum thickness.

[0015] As a further improvement of the present utility model, the braided shielding layer can be a composite shielding structure of aluminum-plastic composite tape wrapping and braided copper wire.

[0016] As a further improvement of the present utility model, the conductor shielding layer adopts a braided metal wire process, and the second semi-conductive tape is used to prevent the shielding single wire from scratching the insulating layer.

[0017] Beneficial effects

[0018] 1. A first semi-conductive tape is wrapped around the conductor. Using a semi-conductive nylon tape with a lapping rate of not less than 20% reduces the risk of partial discharge.

[0019] 2. The three-layer co-extrusion structure eliminates the mixing of impurities between layers and ensures the electrical performance of the product.

[0020] 3. Prevent the shielding single wire from scratching the insulating layer: A second semi-conductive tape is wrapped around the three-layer co-extrusion structure with a lapping rate of not less than 20%. Since the conductor shielding layer structure adopts a braided metal wire process, the wrapped second semi-conductive tape can effectively prevent the shielding single wire from scratching the insulating layer, providing additional protection for the insulating layer and enhancing the reliability and safety of the cable.

[0021] 4. A braided shielding layer is provided outside the second semiconductive tape. The braided shielding layer is provided outside each insulated conductor to form a phase-separated shield, which can effectively equalize the electric field.

[0022] 5. Through a number of special electrical tests including load cycle tests, DC superimposed switching impulse voltage tests and subsequent DC tests, this cable has proven that it can maintain insulation without breakdown under complex stress conditions such as repetitive loads, polarity reversal, switching overvoltage, etc. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] Figure 1 is a schematic structural diagram of the present utility model;

[0024] Explanation of the reference numerals in the schematic diagram: <00000�4>1. Conductor; 2. First semiconductive tape; 3. Conductor shield layer; 4. Insulation layer; 5. Insulation shield layer; 6. Second semiconductive tape; 7. Braided shielding layer; 8. Halogen-free low-smoke flame-retardant polypropylene rope; 9. High flame-retardant tape; 10. Outer sheath. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0026] To further understand the content of the present utility model, the present utility model will be described in detail in combination with the drawings and specific embodiments.

[0027] In the description of the present utility model, it should be understood that the orientation or positional relationship indicated by the terms "center", "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", etc. is based on the orientation or positional relationship shown in the drawings. It is only for the convenience of describing the present utility model and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore should not be construed as a limitation to the present utility model.

[0028] In the description of the present utility model, the meaning of "several" is one or more, the meaning of "multiple" is two or more, "greater than", "less than", "exceeding", etc. are understood as not including the present number, "above", "below", "within", etc. are understood as including the present number. If the first and second are described only for the purpose of distinguishing technical features, they should not be construed as indicating or implying relative importance or implicitly indicating the quantity of the indicated technical features or implicitly indicating the sequence relationship of the indicated technical features. <00℃0062>

[0029] In the description of the present utility model, unless otherwise clearly defined, words such as "set", "install", "connect", etc. should be understood in a broad sense, and those skilled in the art can reasonably determine the specific meanings of the above words in the present utility model in combination with the specific content of the technical solution.

[0030] Medium-voltage DC ethylene propylene rubber insulated LSZH flame-retardant cable for ships, including a multi-strand stranded tinned copper conductor 1. The conductor structure adopts regular concentric stranding, so as to ensure the stability of the conductor structure and the roundness of the appearance while ensuring the resistance; the outer-layer stranding pitch diameter ratio is not greater than 12, and the conductor bunching and double stranding both adopt the same-direction stranding to effectively reduce the outer diameter, improve the flexibility of the product at the same time, facilitate installation and construction, and the single-wire tension should be evenly controlled to effectively avoid single-wire skipping strands.

[0031] Since the conductor adopts a multi-strand stranded conductor, it has a great impact on the partial discharge performance of the product. To fully reduce this risk, a first semiconductive tape 2 is overlapped and wrapped outside the conductor. A semiconductive nylon tape is used, and the lapping rate is not less than 20%.

[0032] There is a three-layer co-extrusion structure outside the first semiconductive tape 2, which are the conductor shielding layer 3, the insulation layer 4 and the insulation shielding layer 5 from the inside to the outside in sequence. Among them, the conductor shielding layer 3 adopts a cross-linked semiconductive rubber inner shielding material, and the extruded nominal thickness is 1.0 mm; the insulation layer ④ adopts natural ethylene propylene rubber, and the extruded nominal thickness is 2.5 mm. The average insulation thickness ≥ nominal thickness, the thinnest insulation thickness ≥ 90% nominal thickness, and the concentricity ≤ 1.15; the insulation shielding layer 5 adopts a cross-linked peelable semiconductive rubber outer shielding material, and the extruded nominal thickness is 0.8 mm. This three-layer co-extrusion structure realizes the simultaneous extrusion of the three layers through the co-extrusion process, using different bodies, the same extrusion head, and special die design. The advantages are as follows: it can avoid the mixing of impurities between layers and ensure the electrical performance of the product.

[0033] A second semiconductive tape 6 is wrapped outside the three-layer co-extrusion structure, and the lapping rate is not less than 20%. Since the conductor shielding layer 3 structure adopts a braided metal wire process, the wrapped second semiconductive tape 6 can prevent the shielding single wire from scratching the insulation layer.

[0034] There is a braided shielding layer 7 outside the second semiconductive tape 6, which is braided with tinned copper wires. The density of the braided shielding layer 7 is not less than 80%. If necessary, the braiding density can be increased according to the user's requirements; it can also adopt forms such as aluminum-plastic composite tape wrapping + braided copper wire composite shielding to further improve the electromagnetic shielding performance of the cable. The braided shielding layer 7 is arranged outside each insulated wire core to form a phase shielding, effectively equalizing the electric field.

[0035] The above-mentioned conductor 1, first semiconductive tape 2, three-layer co-extrusion structure, second semiconductive tape 6 and braided shielding layer 7 are stranded into an insulated wire core in the right direction after stranding, and the stranding pitch diameter ratio ≤ 15. In this embodiment, a halogen-free low-smoke flame-retardant polypropylene (PP) rope 8 is filled between the four insulated wire cores. The filling material should be suitable for the working temperature of the cable, compatible with the insulating material, and not adhere to the insulated wire core. After the four insulated wire cores are stranded, a high-flame-retardant tape is wrapped, and the tape lapping rate ≥ 15%.

[0036] The outermost layer is extruded with an outer sheath 10. The outer sheath 10 is selected from irradiated cross-linked polyolefin sheath materials with stable heat-aging performance, low smoke, halogen-free, low toxicity, flame retardant, oil resistance, and weather resistance. The material performance indicators meet the requirements of the standard GJB 1916 / GJB 774A. At the same time, the sheath material should also be resistant to γ-rays, with an oxygen index ≥ 32%. When necessary, characteristics such as anti-rat, anti-termite, and anti-ultraviolet can be considered. The average value of the sheath thickness ≥ the nominal thickness, and the thinnest part of the sheath ≥ 80% of the nominal thickness. The maximum thickness of the sheath on any cross-section of the cable ≤ 1.66 times the minimum thickness. When extruding the sheath, a halogen-free, low-smoke, and low-compression ratio screw should be selected, with a compression ratio of 1∶1.15. The die is of the extrusion type, effectively ensuring the non-roundness of the finished cable.

[0037] The medium-voltage DC ethylene-propylene rubber insulated LSZH flame-retardant cable for ships provided in this embodiment passes the following three special performance tests.

[0038] 1. Load cycle test: 12 24-hour load cycles under negative polarity UT(=1.85U0, U0 = 12.5 kV), 12 24-hour load cycles under positive polarity UT, and 3 48-hour load cycles under positive polarity UT; the test requires that the cable does not break down.

[0039] 2. DC superimposed switching impulse voltage test: Apply 10 consecutive pulses of U0→Up2,s(Up2,s = 30 kV), 10 consecutive pulses of U0→-Up2,s, 10 consecutive pulses of -U0→-Up2,s, and 10 consecutive pulses of -U0→Up2,o(Up2,o = 30 kV) in sequence, and no breakdown is required.

[0040] 3. Subsequent DC test: After completing the impulse test, apply a negative polarity DC voltage UT(2h) without heating, and no breakdown is required.

[0041] The performance of the finished cable meets all the above test requirements.

[0042] The test conditions for the DC superimposed switching impulse voltage test are specifically as follows: 10 consecutive pulses from U0→Up2,s(Up2,s is 1.15 times the maximum absolute peak voltage of the switching overvoltage, the voltage value that the cable system may withstand when the switching overvoltage and the actual DC voltage have the same polarity, Up2,s = 30 kV)+10 consecutive pulses from U0→-Up2,s+10 consecutive pulses from -U0→-Up2,s+10 consecutive pulses from -U0→Up2,o(Up2,o is 1.15 times the maximum absolute peak voltage of the switching overvoltage, the voltage value that the cable system may withstand when the switching overvoltage and the actual DC voltage have opposite polarities, Up2,o = 30 kV); the test requires that the cable does not break down.

[0043] The above has schematically described the present utility model and its implementation manners. This description is not restrictive, and only one of the implementation manners of the present utility model is shown in the accompanying drawings. The actual structure is not limited thereto. Therefore, if those of ordinary skill in the art are inspired by it and design, without creative efforts, structural manners and embodiments similar to the technical solution without departing from the gist of the creation of the present utility model, they shall fall within the protection scope of the present utility model.

Claims

1. A medium-voltage DC ethylene propylene rubber insulated LSZH flame-retardant cable for ships, characterized in that: It includes a multi-strand stranded tin-plated copper conductor, with a first semiconducting strip wrapped around the conductor. The first semiconducting strip has a three-layer co-extruded structure, consisting of a conductor shielding layer, an insulation layer, and an insulation shielding layer from the inside out.

2. The LSZH flame-retardant medium-voltage DC ethylene propylene rubber insulated cable for ships according to claim 1, characterized in that: The three-layer co-extruded structure is wrapped with a second semi-conductive strip, with an overlap rate of ≥20%.

3. The LSZH flame-retardant medium-voltage DC ethylene propylene rubber insulated cable for ships according to claim 2, characterized in that: The second semiconducting strip is braided with tin-plated copper wire to form a braided shielding layer with a braiding density of ≥80%, which constitutes phase-separated shielding.

4. The LSZH flame-retardant medium-voltage DC ethylene propylene rubber insulated cable for ships according to claim 1, characterized in that: The conductor shielding layer uses cross-linked semi-conductive rubber inner shielding material with an extruded nominal thickness of 1.0 mm; The insulation layer is made of natural ethylene propylene rubber, with an extruded nominal thickness of 2.5 mm, an average insulation thickness ≥ nominal thickness, a minimum insulation thickness ≥ 90% of the nominal thickness, and a concentricity ≤ 1.

15. The insulating shielding layer is made of cross-linked peelable semi-conductive rubber outer shielding material with a nominal extrusion thickness of 0.8 mm.

5. The LSZH flame-retardant medium-voltage DC ethylene propylene rubber insulated cable for ships according to claim 2, characterized in that: The conductor, the first semiconducting strip, the three-layer co-extruded structure, the second semiconducting strip, and the braided shielding layer are cabled and then right-hand stranded into an insulated core with a stranding pitch ratio ≤15.

6. The LSZH flame-retardant medium-voltage DC ethylene propylene rubber insulated cable for ships according to claim 5, characterized in that: During cabling, halogen-free, low-smoke, flame-retardant polypropylene rope is filled between the insulated cores.

7. The LSZH flame-retardant medium-voltage DC ethylene propylene rubber insulated cable for ships according to claim 5, characterized in that: After the cable is assembled, wrap it with high flame-retardant tape.

8. The LSZH flame-retardant medium-voltage DC ethylene propylene rubber insulated cable for ships according to claim 7, characterized in that: The outermost extruded outer sheath is made of irradiated cross-linked polyolefin sheath material. The average thickness of the sheath is greater than or equal to the nominal thickness, the thinnest part is greater than or equal to 80% of the nominal thickness, and the maximum thickness of the sheath on any cross section is less than or equal to 1.66 times the minimum thickness.

9. The LSZH flame-retardant medium-voltage DC ethylene propylene rubber insulated cable for ships according to claim 3, characterized in that: The braided shielding layer can be a composite shielding structure consisting of aluminum-plastic composite tape wrapped with braided copper wire.

10. The LSZH flame-retardant medium-voltage DC ethylene propylene rubber insulated cable for ships according to claim 2, characterized in that: The conductor shielding layer is made using a braided metal wire process, and the second semiconducting tape is used to prevent the shielding monofilaments from puncturing the insulation layer.

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