Jack knowledge about cable:Safety requirements of the cable

In the power transmission , especially in modern super high voltage and high voltage power transmission process , the security is often a very important issue . It plays an important role in the power transmission cables which security demands? Power cable companies who generally have the following five points.

1 cable cross each other , the high-voltage cables should be below the low-voltage cables . If one of the cables around the crossing point within the range of 1m or wear protective tube separated by a partition , the minimum allowable distance of 0.25m.

2 cables with heat pipe close to or intersect , if insulation measures , a minimum distance of parallel and intersecting 0.5m respectively and 0.25m.

3 cable railway or road intersection should wear protective tube to protect the pipe should extend beyond 2m rail or road .

4 cables from the building foundation should be able to ensure that the cable is buried outside the building bulk water ; cable into the building should wear protective tube , the tube should be beyond the protection of bulk water outside the building .

5 should distance between the ground directly buried cables and grounding devices generally 0.25 ~ 0.5m; direct buried cable burial depth , generally not less than 0.7m, and should be buried in the permafrost .

Jack knowledge about cable:Jack knowledge about cable:knowledge of Fireproof cable

With ten years of development blowout cabling industry , a growing number of internationally renowned manufacturers saw the huge potential of the Chinese market, the first to enter the Chinese manufacturers such as Compton , have Mimi eat a big fat , the more An increasing number of manufacturers want to enter the Chinese market share. Thus , with the end of the era of low and profits , the major manufacturers have come up with their own special skill , desire to dominate the market because of a maturing market has not just rely on international brand awareness and the introduction of foreign technology will be able to gain the initiative right , and to consider how to keep more of the overall pace of development China cabling industry , how can the introduction of foreign technology and marketing and transformation of localization in order to expand its market share in China.

In the network transmission is the most valuable information instead of network equipment. There was such a news , a certain public house on fire, she would only hold a drawer to escape from the scene , the people asked her what ah ! So precious ? She said this is my small to large photos, other things are valuable , and photos are priceless , burned it forever gone. Visible information is non-renewable, it never once lost , so people do everything possible to back up the data through a variety of means to send data through a stable network , placed them in a safe place . People gradually integrated wiring system against external invasion and avoid turning the direction of the external hazards , so the cable fire became their top priority.

It is often said Shuihuowuqing since man discovered fire, and the fire is not only accelerated the development of human civilization , but also to bring the destruction of human civilization , many ancient civilizations destroyed by fire . Similarly, the fire also burned cabling system that allows network transmission interruption. Also, if the cable produce large amounts of toxic gases and soot in the combustion process , the escape would have a significant impact on staff , and even become safety hazards. Therefore, countries engineers are stepping up research personnel for data backup and more secure fire lines .

Fireproof cable type

Wider application of the fire at this stage there are UL Series cables and flame retardant cable LSZH cable into two categories. Import products mainly from the Americas and Europe , due to the fire cable standard in America and Europe are not compatible , fire ideas are very different , and therefore , in the choice of the Party and the Institute products are in a passive state , each with its own the truth, often end up in accordance with the actual situation of funds to choose from.

UL flammability standards mainly in the following grades : CMP, CMR, CM, CMG, CMX.

1 ) booster stage -CMP level ( air combustion test / Tolstoy sodium duct experiments Plenum Flame Test / Steiner TunnelTest)
It is UL fire safety standards in the most demanding cable (Plenum Cable), the applicable safety standards UL910, experimental device specified in the horizontal ducts laying multiple samples , (300,000 BTU / Hr) gas burner combustion 87.9KW 20 minutes . Eligibility criteria for the flame must not extend beyond the gas burner flame front from 5 feet . The maximum peak optical density of 0.5 , the average value of the maximum density of 0.15 .
Such cables are usually installed in the CMP pressurized air return ducts or ventilation system air handling equipment used in Canada and the United States is recognized using . Good flame retardant performance meets UL910 standard FEP / PLENUM materials, flame retardant than meets IEC60332-1 and IEC60332-3 standard halogen material , burning up the concentration of smoke is low.

2 ) Riser -CMR level ( vertical burning test Riser Flame Test)
This is a commercial grade UL standard cable (Riser Cable), the applicable safety standards UL1666. In the simulation experiments predetermined vertical axis Cable samples , the gas burner with a predetermined 154.5KW (527,500 BTU / Hr) 30 min. Eligibility criteria for the flame can not spread to the upper 12 feet high room. Riser cable is not smoke concentration norms , generally vertical and horizontal cabling for floor use .

3 ) commercial grade -CM level ( vertical burning test Vertial Tray Flame Test)
This is a commercial grade UL standard cable (General Purpose Cable), the applicable safety standards UL1581. Experimental regulations laying multiple samples on a vertical stand 8 feet high , with a prescribed burn at 20KW (70,000 BTU / Hr) 20 minutes. Eligibility criteria for the flame can not spread to the upper end of the cable and self-extinguish . Similar UL1581 and IEC60332-3C, just different cabling roots. Commercial-grade cable is not smoke concentration standard, generally used only on the same floor level traces should not be used on vertical wiring floors .

4 ) General Purpose -CMG level ( vertical burning test Vertial Tray Flame Test)

It is common to UL standard grade cables (General Purpose Cable), the applicable safety standards UL1581. Similar to the commercial and general level of test conditions , the same as approved for use in Canada and the United States . General Purpose Cable specification does not smoke concentration , generally apply only to trace the same floor level , should not be used on vertical wiring floors .

5 ) household level - CMX level ( vertical burning test Vertial Wire Flame Test)
This is the UL standard household -level cable (Restricted Cable), the applicable safety standards UL1581, VW-1. Experimental samples provisions remain vertical , with the torch burning test (30,000 TU / Hr) 15 seconds, then stop for 15 seconds , repeated 5 times. Eligibility criteria for the flame must not exceed 60 seconds remaining , the sample can not burn more than 25% , the pad at the bottom of surgical cotton falling objects can not be ignited . UL1581-VW-1 similar to IEC60332-1, just different burning time . This grade does not smoke or toxic specification , only for laying a single cable system in a home or small office . These cables should be installed in bundles must casing. LSZH cables (LSOH).

LSZH cable by definition is less smoke after a fire , halogen-free cable. LSZH cable in principle is to let the flame does not produce a lot of gas and smoke when burned , so that people will not burn a lot of harm caused , greatly improving the survival rate of people in the fire.

LSZH cable test requirements, meet three requirements:
Flammability Requirements: You must have flame retardant LSZH cable . There are two flame retardant grades were required to comply with IEC 60332.1 ( a single cable vertical burning test ) and IEC 60332.3C ( vertical flame spread of bunched cable test ) . IEC 60332.1 which requires the use of a common flame retardant cable requirements, and IEC60332.3C requires relatively high level of flame retardant belong trunk .
Smoke density requirements : LSZH cable to carry the smoke density test . It is used in a confined space fire burning cables until the flame is extinguished after the final indoor smoke density test , required in the case of cigarettes , the ability to reach 60% light transmission , thus ensuring that people can see the smoke road .

Toxicity requirements: current toxicity testing methods several species, such as mice test and so on. In LSZH cable is used in halogen acid gas emission test ( test for low halogen ) and gas acidity test ( for halogen-free test ) . The test principle is halogen gas material at high temperatures ( respectively 800 ℃ and 935 ℃) generated by the analysis method to determine the halogen content .

Describes some of the information IEC 60332.1 level equivalent to the requirements of UL CM (IEC 60332.2 is a small diameter cable testing methods , alternative testing methods that can not be used when testing using 60332.1 ), IEC60332.3C equivalent to the requirements of UL CMR level . In fact, this four standard test methods are not the same , can not be directly compared.

In summary , the formation of two series of cables , one is flame-retardant cable CMX America ( U.S. standard cables clearly requires CMX halogen to increase the decomposition temperature of the cable ) ; the other is European FR / LSOH flame / LSZH cables.

Jack knowledge about cable:knowledge of ground wire

In life, the ground wire is more commonly used as a cable, Here we give a brief knowledge of the ground wire! 
Ground wire is directly connected to the earth wire, also called safe return route, it put pressure direct danger to pass the Earth, considered a lifeline. 
Household appliances due to the poor insulation or humid environment will cause its shell with a certain static, in severe electric shock. In order to avoid such occurrences in the electrical wires may be connected to a metal housing at the other end of the wire to earth, once the electrical leakage occurs into the static ground line will release the earth. In addition to electrical maintenance personnel in the use of electric iron welding circuit, sometimes because of the charged electric iron and damaged electrical breakdown of the integrated circuit, which is more important. Friends sometimes use the computer to ignore the main case is grounded in fact, connected to the host computer root shell ground, to a certain extent, can prevent crashes phenomenon. 
In the power system ground: an important tool to have when the power voltage of equipment and lines appear unexpectedly assurance staff. By ministerial regulations, the ground wire must be more than 25mm 2 soft bare copper wire.

Brief introduction

Appliances, ground wire is connected to the electrical equipment enclosure and other parts in a timely manner will be due to various causes unsafe charge or leakage current export lines.

(1) high-voltage ground wire effect: high ground wire is used for lines and substation construction, to prevent near the charged body to ensure the safety of the use or misuse of electrostatic induction shock closing time. 
(2) high-voltage ground wire structure: portable high voltage ground wire from the insulated operating rod, wire clips, short routes, grounding wire, grounding terminals, bus clip, earth clamp. 
(3) high-voltage ground wire production process: the fine craftsmanship - wire clamp, earth clamp is made of high quality aluminum die casting; operating rod using epoxy color tube, good insulation properties, high strength, light weight, bright appearance smooth; soft ground using multi-strand copper wire twisted together high quality soft, and covered with soft, high temperature transparent insulating sheath can be worn on the ground to prevent the use of copper, copper wire fatigue testing requirements, ensure workers safety in operation. 
(4) ground wire Specifications: according to ministerial regulations, the ground wire must be more than 25mm 2 soft bare copper wire.

Resistance requirements

High short-circuit ground wire to ground resistance requirements determine the quality of the ground wire, generally in accordance with the power industry DL-T879-2004 technical requirements of each cross-sectional area of ​​the ground wire to ground resistance is not greater than the following values: 
DC resistance is measured between the lugs, 
For 16mm2, 25mm2, 35mm2, 50mm2, 70mm2, 95mm2, 120mm2 various sections, 
Average per meter were less than the resistance value should 1.24mΩ, 0.79mΩ, 0.56mΩ, 0.40mΩ, 0.28mΩ, 0.21mΩ, 0.16mΩ.

High voltage ground wire classification

(1) high-voltage ground wire in accordance with the use of the environment can be divided into: indoor busbar grounding wire (JDX-NL) and outdoor line-type ground wire (JDX-WS). (2) high-voltage ground wire in accordance with the voltage level can be divided into: 10KV ground wire, 35KV high voltage ground wire, 110KV grounding line, 220KV high voltage ground wire, 500KV high voltage ground wire 
Instructions for use 
(1) When mounted ground: first link earth clamp, followed by electrical connection clip; When removing the grounding line, the program must first disconnect power clip, after the demolition of the grounding clip. 
(2) Installation: soft copper phase grounding copper nose on his eyes fixed on the ground rod grounding Clips (electrical connection there are the fixed and movable) corresponding position on the monocular copper nose on the ground conjunct fixed on the ground or ground pin clip, constitute a complete set of ground wire. 
(3) verification of voltage levels and ground rod to operate the equipment are the same voltage level. 
(4) Ground partakers with soft copper and modular, grounding rods have flat type and double reed hook clamp.

Maintenance

Before using portable short-circuit ground wire should confirm a priori power outage, make sure no voltage on the device after the. First grounding clamp connected to the ground network or flat iron, then stick with a ground operation wire end line classes were tightened on the device leads. When removing the short-circuit ground wire, coinciding with the opposite order. 
Short-circuit ground wire installed from it and live equipment, taking into account the impact of the grounding wire pendulum, its safe distance should not be less than the value of the new regulations, "electricity safety regulations."

Prohibited method but with winding is shorted to ground without clamp.

Suspension points if ground, use copper for grounding clamp or a dedicated ground connection; If no fixed ground available; are available temporary grounding, grounding buried depth should not be less than 0.6m. 
Portable short-circuit ground wire should be properly kept. Before each use, check carefully whether it should be in good condition, no bare annealed copper wires exposed, no loose nuts shall not be used. 
Portable short-circuit ground wire test cycle every five years, with factory inspection test items. After passing the test of portable short-circuit ground wire after being subjected to short-circuit, short-circuit current withstand should be based on the size and appearance inspection judgments in general should be scrapped

Review, summarize recent knowledge of the cable!

Recently, Jack has to share the nine cables knowledge blog!
To share a lot of knowledge of the cable, the cable basics knowledge, Main introduces three categories according to the application, gave a briefing on the knowledge of the power cable, Main introduce power cable history, type and structure! And how to buy power cable.
Then gave a briefing on fiber optic cable, xlpe cable, AAC (Aluminum alloy cable) cable, high voltage cable, control cable and other cables commonly used structures and uses, and gave a briefing specifically Wire and cable manufacturing process, so that we With the understanding of manufacturing cables, yesterday, to everyone Distinguish between wire and cable, wire and cable let everyone have a deeper understanding!
To conclude, Jack has to share so much knowledge of the cable, it makes me feel very proud, I often see his old blog, to check whether there is an error, and every time can learn something new, today, as summed up, not to share the knowledge of the cable, I hope everyone can learn more things, thank you!

Jack knowledge about cable:Distinguish between wire and cable

People often think of wire and cable be confused, the Jack will give you the difference between the wire and cable!

Wire
Carrier conduction electricity use.

Wire and cable
For transmission (magnetic) energy, information and realize electromagnetic energy conversion of wire products.

Distinguish between wire and cable

The wire is composed of one or a plurality of soft wire, wrapped with a protective layer of light; cable is composed of one or a plurality of insulating coating wire, wrapped with metal or rubber tough outer. Cables and wires are generally consists of a core wire, insulating sheath and the protecting scarfskin consists of three parts. The following characteristics of common cable: CEF — ethylene propylene rubber insulated rubber chloroprene, flame retardant power cable for ship. CVV — PVC insulation, flame retardant power cable with PVC sheath for ship. Oxygen line often use BV, BX, RV, RVV series wire, wherein: BV — copper core PVC insulated wires, long-term permissible temperature 65 ℃, the lowest temperature of -15 ℃, working voltage 500V AC, DC 1000V, fixed laid indoor, outside, can be laid can also be concealed. BX — copper core rubber insulated wire, the highest use temperature is 65 ℃, apply to indoor. RV — Polyvinyl chloride insulated single core cable, the highest use temperature is 65 ℃, the minimum temperature -15 ℃, working voltage 250V AC, DC 500V, used as a instrument and equipment internal wiring. RVV — copper core PVC insulated and sheathed flexible cords, allowing long-term working temperature is 105 ℃, the working voltage 500V AC, DC 1000V, used in wet, mechanical protection requirements high, often moving and bending of the occasion. In fact, “the wire” and “cable” and there is no strict boundaries. Usually the core number less, products with small diameter, simple structure of the product called wires, no insulation called bare wire, the other called cables; conductor cross-sectional area of the larger (greater than 6 mm2) called the high wire, the smaller (less than or equal to 6 mm2) called small wires, insulated wire, also known as wire cloth that is relatively simple, easy to understand!! cable generally have 2 layers of insulation, most of them are multi core structure, around the cable tray, usually more than 100 meters in length. The wire is usually single layer insulation, single core, 100 meters roll, radio disc. Cable common type: VV said: PVC insulated (first V), PVC sheath (second V) YJV22 said: crosslinking PVC insulation, PVC sheath (YJ) (V), steel tape armored (22) and add “ZR” or “FR” for flame retardant cable (wire). Add “L” to aluminum wire type is simple: BVV– PVC insulated and sheathed copper core PVC insulated copper wire, BV–, BYJ– copper core crosslinked polyolefin insulation wire, PVC insulated copper wire BVR–, BX– rubber insulated copper wire, RHF– chloroprene rubber copper core wire.

(2) small diameter called “line”; large diameter is called “cable”.

(3) is called the “line” has the advantages of simple structure; complex called “cable”.

But with the expanding usage, many varieties of “line cable”, “cable cable”. So there is no need to distinguish strictly.

In daily habits, the household cloth wire is house wire, the power cable referred to as cable.

Wire and cable mainly includes bare wire, winding wires, power cables, communication cables and optical cables, electrical equipment with.

Jack knowledge about cable:knowledge of high voltage cable

During electric power transmission transmission, the higher the voltage, the less the loss of power! With the development of insulating materials and technology, and now has a large number of high-voltage cable production and extensive application! Here jack'll tell you about the structure of high-voltage cables, usage characteristics, Construction and other knowledge!

High voltage cable is a power cable, means for transmitting the power cable 10KV-35KV (1KV = 1000V) between the power transmission and more used in the main road.

The structure of high-voltage cables

High voltage cable from the inside to the outside components include: conductor, insulation, inner sheath, fillers (armored), external insulation. Of course, armored high-voltage underground cables are mainly used, can resist the oppression of high intensity on the ground, while preventing other external damage.

High-voltage cable to use features

The product is suitable for AC rated voltage 35KV and below for power transmission and distribution lines with a fixed set granary, the maximum long-term working temperature of conductor 90 degrees, short circuit (the longest time not to exceed 5S), the cable conductor maximum temperature does not exceed 250 degrees.

Construction

Like other power cables, high-voltage cables have the structural elements of one or more conductors, insulation, and a protective jacket. High-voltage cables differ from lower-voltage cables in that they have additional internal layers in the insulation jacket to control the electric field around the conductor.

For circuits operating at or above 2,000 volts between conductors, a conductive shield may surround each insulated conductor. This equalizes electrical stress on the cable insulation. This technique was patented by Martin Hochstadter in 1916;[1] the shield is sometimes called a Hochstadter shield. The individual conductor shields of a cable are connected to earth ground at the ends of the shield, and at splices. Stress relief cones are applied at the shield ends.

Cables for power distribution of 10 kV or higher may be insulated with oil and paper, and are run in a rigid steel pipe, semi-rigid aluminum or lead sheath. For higher voltages the oil may be kept under pressure to prevent formation of voids that would allow partial discharges within the cable insulation.

Sebastian Ziani de Ferranti was the first to demonstrate in 1887 that carefully dried and prepared paper could form satisfactory cable insulation at 11,000 volts. Previously paper-insulated cable had only been applied for low-voltage telegraph and telephone circuits. An extruded lead sheath over the paper cable was required to ensure that the paper remained absolutely dry.

Vulcanized rubber was patented by Charles Goodyear in 1844, but it was not applied to cable insulation until the 1880s, when it was used for lighting circuits.Rubber-insulated cable was used for 11,000 volt circuits in 1897 installed for the Niagara Falls Power Generation project.

Mass-impregnated paper-insulated medium voltage cables were commercially practical by 1895. During World War II several varieties of synthetic rubber and polyethylene insulation were applied to cables.Modern high-voltage cables use polymers or polyethylene, including (XLPE) for insulation.

Jack knowledge about cable:knowledge of Wire and cable manufacturing process

Hello everyone, It’s time to share my knowledge of cable now,Today I will share the knowledge of Wire and cable manufacturing process.

Process

Wire and cable manufacturing and production of most of the mechanical and electrical products are completely different. Another commonly used mechanical and electrical products will be assembled into component parts , multiple parts and then assembled into a single product , the product measured by number of units or pieces . Wire and cable is the basic unit of measurement of length . All are from the conductor wire and cable processing began , with the insulation layer by layer in the periphery of the conductor, shielded cabling , protection layer made ​​of wire and cable products. The more complex structure of the product , the more superimposed layers.

Technological Characteristics

1. large length of continuous overlay combination mode of production , the impact on the global wire and cable production and controllability , which involves and affects:

( 1 ) production process and equipment layout

Various equipment production plant product requirements must be reasonable discharge process , so that the various stages of semi-finished products , sequential flow. Device configuration to be considered and balanced production capacity of different production efficiency , and some equipment may have to configure two or more , in order to make the production capacity of the production line can be balanced . Thus a combination of reasonable matching device layout and production sites , must be based on the product and production to balance considered.

( 2) The production organization and management

Production organization and management must be scientific and reasonable, accurate and careful , meticulous , scrupulous operator must perform according to process requirements , any link problems will affect the process of smooth, affect product quality and delivery. Especially multi -core cable , one pair or the basic unit length is short , or quality problems , the entire length of cable will be enough to cause scrapped. Conversely, if a cell is too long , must be sawn waste.

( 3 ) Quality Management

Large continuous length superimposed combination of production, so that any one part of the production process , some problems occur instantaneously , it will affect the quality of the entire cable . The more quality defects occur in the inner layer , but did not discover the termination of production, then the greater the losses . Because unlike the production of wire and cable products assembled , you can open other pieces of heavy equipment and replacement ; either a part or the wire and cable process quality problems, these cables is almost irreversible and irreparable. Post- processing is very negative , not sawn downgrade is either scrap the entire cable . It is not open to reload.

Quality Management wires and cables must be run through the entire production process . Quality inspection departments to manage the entire production process inspection tour , the operator self-inspection, mutual inspection process from top to bottom , this is to ensure product quality , and means an important guarantee for improving economic efficiency of enterprises .

2 . Production process multiple categories , material flow

Wire and cable manufacturing process involving a wide range of categories , and pressure from the non-ferrous metal smelting and processing, to plastics , rubber, paint and other chemical technology ; fiber material wrapping , weaving and other textile technology , the metal strip around the bag and metal materials the longitudinally welded metal forming process , and so on .

Wire and cable manufacturing a variety of materials used , not only classes , varieties , specifications, and large quantities. Therefore, the amount of various materials , spare capacity , batch and batch cycle must be approved . Meanwhile , the decomposition of waste treatment, recycling , reuse and waste disposal , as an important part of management , good material quota management , attention to conservation work .

Wire and cable production, from raw materials and various auxiliary materials and out of storage , the process of transfer to the semi-finished product storage, factory , material flow, must be rational distribution , dynamic management .

3 . Special equipment and more

Wire and cable manufacturing industry that has the technological characteristics of specialized production equipment , in order to adapt the structure , performance requirements of cable products to meet the large length of continuous high-speed production requirements as much as possible , so as to form a cable manufacturing equipment series. Such as extrusion machine, cable machine, stranding machine, around the charter series.

Closely related to the development of wire and cable manufacturing processes and equipment , and promote each other. The new process requirements, to promote the emergence and development of new specialized equipment ; conversely , the development of new equipment , but also to improve the promotion of the development and application of new technology . Such as drawing, annealing , tandem extrusion line ; physical foaming production lines and other special equipment , wire and cable manufacturing process to promote the development and improvement , improve product quality and production efficiency of the cable.
Second, the main craft wire and cable\

Power cables

Wires and cables through : drawing , stranding , covering three processes to produce finished , the more complex model specifications , the higher reproducibility.

1 . Drawn

In the external force so that the metal in the metal working pressure is forced through the die ( pressure roller ) , a metal cross-sectional area is compressed to obtain technical processing method and the shape and size of the cross-sectional area required called metal drawing .

Drawing process of : single strands system and stranding drawn .

2 . Stranding

To improve the flexibility of wire and cable , the overall degree , so two or more single-wire , interwoven according to a predetermined direction called stranding .

Stranding process points : Conductor stranding , cabling , weaving , wire armouring and winding .

3 . Coated

According to the different performance requirements of the wire cable , the use of special equipment in the outside conductor covering a different material . Coating process points :

A. Squeeze bag : rubber, plastic, lead, aluminum and other materials.
B. Longitudinal package : rubber , wrinkles aluminum material.
C. Wrapping: ribbon tape , mica , E-glass fiber tape, non-woven fabrics , plastic tapes , linear cotton , silk and other fibrous materials.
D. Dip : insulating paint , asphalt , etc.

Third, the basic plastic wire and cable manufacturing process

1 . Copper, aluminum, single strands system

Commonly used copper wire cable , aluminum material , at room temperature , the tensile drawing machine using a die or a number of channels through the die orifice to reduce the cross section , increasing the length , strength. Drawing is the first procedure of each wire and cable companies , the main process parameters are brushed with mold technology.

2 . Annealed monofilament

Copper, aluminum filaments heated to a certain temperature , recrystallization of the monofilament way to improve the toughness and reduce the strength of the monofilament to meet the conductive core wire and cable requirements . The key is to prevent oxidation annealing process copper wire .

3 . Stranding conductor

In order to improve the flexibility of wire and cable in order to facilitate the laying of installation , conductive core to take a plurality of monofilaments twisted together . From the conductive core stranded form, can be divided into rules and irregular strands twisted . Irregular Stranded Stranded divided into concentric complex twist, twisted and so special .

To reduce the area occupied by wire , cable geometries shrink , while using the stranded conductor pressed form, so that variation of ordinary semi circular , fan-shaped, W -shaped and pressed round . Such conductors mainly used in the power cable.

4 . Extruded insulation

Plastic wire and cable type used mainly extruded solid insulation , plastic insulation extruded main technical requirements :

4.1. Eccentricity : extruded insulation thickness deviation is reflected important symbol extrusion process level , most of the product structure size and standard deviation values ​​are clearly defined.

4.2 . Smoothness: the surface of the insulating layer extrusion requires smooth , with no rough surface, charred , poor quality of impurities

4.3 . Density : a cross-sectional extruded insulation layer to be dense and firm, not allowed to have visible pinhole to eliminate the presence of air bubbles.

5. Cabling

For multi -core cables in order to ensure molding degrees , reducing the appearance of the cable, generally need to be twisted round . Mechanism of stranded conductor stranding similar, larger diameter section due stranding , they use no way back twist . Cabling technical requirements : First, eliminate shaped stand up and lead insulated cores twisted cables ; second is to prevent insulation from being scratched.

Most of the cable into the cable accompanied by the completion of the other two processes : one is filled to ensure stability after round into the cable and the cable ; one is lashing ensure no loose cable core .

6. Inner sheath

To protect the insulation core is not the pimple armored injury , the need for appropriate protection insulating layer , the protective layer of : extruded inner sheath ( isolation units ) and wrap the sheath ( cushion ) . Wrapping cushion with a cable instead of banding with processes simultaneously.

7 . Armouring

Laying underground cables , the work may be subject to certain positive pressure, choose the steel tape armored structure. Cable laying there in both the positive pressure pulling force occasions ( such as water , drop a large vertical shaft or soil ) , should be used with structured inner wire armouring .

8. Sheath

Structural part of the outer sheath to protect wire and cable insulation to prevent the erosion of environmental factors . The main role of the outer sheath is to improve the mechanical strength of the wire and cable , anti-chemical corrosion, moisture, water immersion , prevents cable burning capabilities. According to the different requirements of the cable directly to the use of an extruder extruded plastic sheath .

Just this today,welcome to talk about cable knowledge together!