Parts of Cable:
1. Conductor (For LV/MV/HT Cables)
2. Conductor Screen (For MV/HT Cables)
3. Filler & Binding Tapes (For LV/MV/HT Cables)
4. Insulation (For LV/MV/HT Cables)
5. Insulation Screen (For MV/HT Cables)
6. Separation Tape (For MV/HT Cables)
7. Bedding (Inner Sheath)
8. Metallic Sheen (For MV/HT Cables)
9. Armor (For LV/MV/HT Cables)
10. Outer Sheath (For LV/MV/HT Cables)
11. Water Blocking Tapes –Optional (For MV/HT Cables)
12. Insulation Tapes–Optional (For MV/HT Cables)
Code: IS: 8130 / IEC 60228/ BS 6360
Material: Class 2 – Annealed Plain / Tinned Copper / Aluminum.
Used for: LV, MV & HV Cables
• Usually stranded copper (Cu) or Aluminum (Al) is used.
• Copper is denser and heavier, but more conductive than aluminum.
• Electrically equivalent aluminum conductors have a cross-sectional area approximately 1.6 times larger than copper, but half the weight.
• The size of the copper / Aluminum conductor forming one of the cores of a cable is expressed in square millimeters (mm2), and the current rating of the cable is dependent upon the cross-sectional area of each core.
• Multi-core Aluminum or copper conductor are produced by two shapes
Circular Conductor: Multi-layers of stranded wires are assembled together to make circular shape.
• To achieve a circular conductor, the number of strands follows a particular progression: 3, 7, 19, 37, 61, and 127 etc, the diameter of each strand being chosen to achieve the desired cross-sectional area of whole conductor.
• Circular shape conductor is normally available used up to 200mm.2
Segmental Conductor: Five segments of compacted conductor in triangle shape of 72 degree are assembled together with separation of non-metallic tapes to reduce the skin effect which reduce the AC conductor resistance.
• Larger sizes have conductors with the strands laid up in a segmental formation; this cable achieves a better space factor and reduces the overall diameter of the cable. It also reduces the inductance of the cable due to decreased spacing between phases
• Segmental conductor is normally available from 1000 mm2 and above.
2. Conductor Screen (Semi Conductor Screen):
Code: IS: 7098/IEC: 60502/ BS: 6622/BS: 7835
Material: Extruded thermo set semi-conducting compound, carbon paper and carbon loaded polymer.
Used for: Cable from 6 to 30kV (MV & HV Cables)
• This screen consists of a lapped copper tape or metallic foil usually less than 1.0mm in thickness, which is the interface between the conductor and the insulation (PVC, XLPE).
• The main purpose of conductor screen is to maintain a uniformly divergent electric field, and to contain the electric field within the cable core.
• Conductor screen is semi-conducting material because semi-conducting materials do not conduct electricity well enough to be a conductor but will not hold back voltage. It smoothes out the surface irregularities of the conductor. The conductor shield makes the voltage on the inside of the insulation the same.
• Semiconducting screening materials are based on carbon black that is dispersed within a polymer matrix. The concentration of carbon black needs to be sufficiently high to ensure an adequate and consistent conductivity.
• The incorporation must be optimized to provide a smooth interface between the conducting and insulating portions of the cable.
• The smooth surface is important as it decreases the occurrence of regions of high electrical stress.
Control Electrical Field: Conductor screen is control the electric field within the insulation and thus the same voltage gradient across it. It also avoids any interaction of the electric stresses due to the voltages on different phase conductors within the same cable.
Reduce Voltage Stress: Conductor Screen helps to reduce voltage stress at the interface between the conducting and insulating components.
• A typical construction for a medium voltage cable consists of an aluminum conductor covered by a screening layer, then by a polyethylene or ethylene propylene rubber insulation followed by a further screening layer. The coefficient of expansion of the insulation layer is typically ten times greater than that of the aluminum and when the cable is at its maximum operating temperature of 90ºC, a large enough gap can be formed to allow electrical discharges to occur. The semi-conducting layer then serves to even out the stresses associated with these discharges, which would otherwise attack the insulation at specific points.
Uniform Electrical Field: A black semi-conducting tape is used to maintain a uniform electric field and minimize electrostatic stresses in MV/HV power cables.
• The external surfaces of the conductor may not be smooth, particularly for stranded conductors, so this layer provides a smooth surface at the same potential as the conductor to keep the electric field consistent all the way around the surface. Without this layer, any small peaks or troughs could cause concentrations of electrical energy which could create small arcs, and over time could erode the insulation layer and cause failure of the cable.
Reduce Electrical Flux line around the each core: It provide a cylindrical, smooth surface between the conductor and insulation
• Semi-conducting compounds also have the effect of filling in the interstices of the conductor giving a smooth surface for the insulation. This reduces the electrical flux lines around each individual wire that make up the conductor, which can reduce the stress by 10-15%.
3. Filler & Binding Tap (Laying-Up):
Material: Non-Hygroscopic PVC / Poly propylene Fiber to maintain roundness of cable.
Used for: LV, MV & HV Cables
• In case of three core cables, the three cores are laid up with polymer compound or non-hygroscopic fillers like polypropylene (PP) fillers and a binder tape is applied with an overlap to provide a circular shape to the cable.
• These binder tapes can be of PVC or foamed Polyethylene.
• Inner Sheath (Bedding) for Armored Cables. Extruded layer of PVC or PE is applied over the laid up cores for armored cables.
Code: IS: 7098, 8130, 14494 / IEC: 60502 / BS: 6622/BS: 7835.
Material: PVC, XLPE, Rubber, Elastomer, EPR.
Used for: LV, MV & HV Cables
• Insulation main Purpose is to withstand the electrical field applied to the cable for its design life in its intended installed environment.
• This will be an extruded layer of XLPE, Elastomer, Rubber or PVC applied over conductor screen under triple extrusion process along with conductor screen and insulation screen.
• There are different Type of Insulation Material used for cable but widely used are
(A) Cross-linked polyethylene: (XLPE)
• They are known as PEX or XLPE Cable. It is form of polyethylene with cross links.
• XLPE creates by direct links or bonds between the carbon backbones of individual polyethylene chains forms the cross linked polyethylene structure.
• The result of this linkage is to restrict movement of the polyethylene chains relative to each other, so that when heat or other forms of energy are applied to the basic network structure cannot deform and the excellent properties that polyethylene has at room temperature are retained at higher temperatures.
• The cross linking of the molecules also has the effect of enhancing room temperature properties.
• The useful properties of XLPE are temperature resistance, pressure resistance (stress rupture resistance), environmental stress crack resistance (esc), and resistance to UV light, chemical resistance, oxidation resistance, room temperature and low temperature properties.
• XLPE cables work for the working voltage of 240 V to 500 KV.
• The jacketing material can be of PVC / Flame Retardant / Flame Retardant Low Smoke / Zero Halogen (LSOH).
Applications: Fire Survival, Under Water Cables, Underground burial, installation on trays and ducts.
(B) Polyvinyl Chloride (PVC)
• They are known as PVC insulated cables are widely used in various fields.
• PVC’s relatively low cost, biological and chemical resistance and workability have resulted in it being used for a wide variety of applications.
• For electric cables the PVC is mixed up with plasticizers. PVC has high tensile strength, superior conductivity, better flexibility and ease of jointing.
• PVC is a thermoplastic material, therefore, care must be taken not to overheat it; it is suitable for conductor temperatures upto 70°C. PVC insulated cables should not be laid when the temperature is less than 0ºC, because it becomes brittle and is liable to crack.
Applications: Low voltage copper conductor PVC cables are extensively used for domestic home appliances wiring, house wiring and internal wiring for lighting circuits in factories, power supply for office automation, in control, instrumentation, submarine, mining, ship wiring applications etc.
(C) Elastomer insulated cable
• These cables are suitable for use where the combination of ambient temperature and temperature-rise due to load results in conductor temperature not exceeding 90°C under normal operation and 250°C under short-circuit conditions.
• This insulation shall be so applied that it fits closely on the conductor (with or without either separator or screen) but shall not adhere to it. The insulation, unless applied by extrusion, shall be applied in two or more layers and it is applicable to cables with a rated voltage up to 1 100 volts.
Applications: Welding Cables, Ship wiring cables, Pressure Tight Cables and cables for submerged connection, Railways locomotives and coach wiring cables, mining cables.
(D) Polyvinyl chloride (EPR).
• For high-voltage cables, the insulation is ethylene propylene rubber (EPR) and for low-voltage cables it is polyvinyl chloride (PVC).
• EPR has good electrical properties and is resistant to heat and chemicals; it is suitable for a conductor temperature up to 85 ºC.
(E) Rubber insulated cable
• These are used in electric utilities such as the generation and transmission of electricity. Long service life under normal environment in nuclear and conventionally powered generating stations plus safety considerations are the significant factors of these electric appliances.
• When exposed to fire, Silicon offers circuit integrity, low smoke evolution, and freedom from halogen acids.
5. Insulation Screen
Code: IS: 7098/IEC: 60502/ BS: 6622/BS: 7835
Material: Extruded thermo set semi-conducting compound, Carbon paper and carbon loaded polymer.
Used for: Cable from 6 to 30kV (MV & HV Cables)
• An extruded layer of semi conducting is applied over the insulation layer to insure that the electric stress is homogenous around the insulated core. The semi conducting layer shall be firmly bonded to the outer layer of the insulation layer.
• The purpose of insulation screen is same as conductor screen.
• The purpose of insulation screen is to reduce voltage stress at the interface between the conducting and insulating component.
• A cylindrical, smooth surface between the insulation and metallic shield.
• Insulation screen is a layer of black cross linked semi conductive compound of approx 1mm thickness and is either fully bonded to the insulation layer, or can be “cold strippable” by hand.
• When terminating or jointing the cables, it is necessary to remove a part of the insulation screen.
6. Bedding (Inner Sheath)
Code: IS: 7098, 1554 / IEC: 60502 / BS: 6622 / BS: 7835.
Material: Thermoplastic material i.e. PVC, Polyethylene, thermosetting (CSP) compound
Used for: LV, MV & HV Cables
• It could be also called inner sheath or inner jacket, which serves as a bedding under cable armoring to protect the laid up cores and as a separation sheath.
• Inner sheath is over laid up of cores.
• It gives circular shape of the cable and it also provides Bedding for the armoring.
• IS: 1554 permits following two methods of applying the Inner Sheath of thermoplastic material i.e. PVC, Polyethylene etc., which is not harder than insulation.
• Inner sheath is provided by extrusion of thermoplastic over the laid up of cores.
• Inner sheath is provided by wrapping at thermoplastic tape.
• All multi-core cables have either extruded PVC inner sheath or thermoplastic wrapped inner sheath, which is compatible with insulation material and removable without any damage to insulation. Single core cables have no inner sheath.
7. Water blocking Tapes
• Water blocking is used to prevent moisture migration.
• Water blocking tapes or Swelling powder should be applied between the conductor strands to block the ingress of water inside the cable conductor (if required).
• Water blocking methods to be considered are as follows:
• Powders: Swell able powders are used as longitudinal water blocks in cables to prevent longitudinal water penetration. These powders swell and expand sufficiently upon contact with water to form a gel-like material to block the flow of water.
• Water-Blocking Tapes: A water-blocking tape is usually a non-woven synthetic textile tape impregnated with, or otherwise containing, a swell able powder.
• Sealed Overlap: To ensure a seal of the overlap, hot-melt adhesives can be used. These adhesives can be extruded or pumped into the overlap seam of a longitudinally formed metallic tape before the seam is closed during cable manufacture.
8. Metallic Screen
Code: IS: 7098 /IEC: 60502 / BS: 6622/ BS: 7835.
Material: Non-magnetic metallic materials Copper Wire / Tape or Aluminum Wire / Strip
Used for: MV & HV Cables
• Medium Voltage & High voltage cables have an earthed metallic screen over the insulation of each core.
• This screen consists one or multi layers of a lapped conductive copper wires, copper tape or metallic foil, lead, aluminum helically with overlap over insulation screen.
• The metallic shield needs to be electrically continuous over a cable length to adequately perform its functions of electrostatic protection, electromagnetic protection, and protection from transients, such as lightning and surge or fault currents.
(1) Shield Electromagnetic radiation: A metallic sheath is used as a shield to keep electromagnetic radiation in the cable.
• The main function of the metallic screen is to nullify the electric field outside of the cable – it acts as a second electrode of the capacitor formed by the cable. The screen needs to connect to earth at least at one point along the route.
• The capacitive charging current and induced circulating currents which are generated under normal operating conditions will be drained away through the screen.
(2) Earth Path: It also provides a path for fault and leakage currents (sheaths are earthed at one cable end).
• The screen also drains the zero-sequence short circuit currents under fault conditions; this function is used to determine the required size of the metallic screen.
• Lead sheaths are heavier and potentially more difficult to terminate than copper tape, but generally, provide better earth fault capacity.
(3) Water Blocking: The other function of metallic sheaths is to water block and form a radial barrier to prevent humidity from penetrating the cable insulation system.
(4) Mechanical Protection: It also provides some degree of mechanical protection to cable.
• Cable shields are non-magnetic metallic materials. The two materials typically used for metallic shields are aluminum and copper. Aluminum requires a larger diameter as a wire or a thicker cross section as tape to carry the same current as copper. At equivalent current-carrying capacity, an aluminum shield will be lighter in weight but about 40% larger in dimensions
Different Types of Metallic Screen
(A) Concentric Copper Wire screens /Tapes
• Lightweight and cost-effective design.
• High short-circuit capacity.
• Easy to terminate.
• Low resistance of screen may necessitate need for special screen connections to limit the circulating current losses.
• Does not form a complete moisture barrier unless water swell able tapes are used under and/or over the copper wires.
(B) Aluminum foil laminate
• Lightweight and cost effective design.
• Moisture proof radial barrier.
• Low short circuit capacity.
• More difficult to terminate – requires special screen connections.
(C) Extruded lead alloy sheath
• Waterproofing guaranteed by the manufacturing process.
• Excellent resistance to corrosion and hydrocarbons (suitable for oil and gas plants).
• Heavy and expensive.
• Lead is a toxic metal whose use is being restricted in some countries.
• Limited capacity for short circuits.
Code: IS: 7098 / IS: 3975 / IEC: 60502 / BS: 6622/BS: 7835.
Material: metallic or non-magnetic Aluminum, Steel wire/strip.
Used for: LV, MV & HV Cables
• The armor provides mechanical protection against crushing forces.
• Armor also can serve as an Earth Continuity Conductor (ECC).
• The armoring type could be:
Mechanical protection of the cable is provided by a single layer of wire / strip strands laid over the bedding. Steel wire or strip is used for 3-core or 4-core cables, but single-core cables have aluminum wire armoring.
• When an electric current passes through a cable, it produces a magnetic field (the higher the voltage the bigger the field). The magnetic field will induce an electric current in steel armor (eddy currents), which can cause overheating in AC systems. The non-magnetic aluminum armor prevents this from happening.
• Magnetic Material’s armoring for 3Ph System: With 3-core or 4-core cables the vector sum of the currents in the conductors is zero, and there is virtually no resultant magnetic flux. In multi-core, armored cables have either single layer of Galvanized Steel wire Armor or Galvanized steel strip applied over inner sheath with left hand lay.
• Non-Magnetic Material’s armoring for 1Ph System: This is not so, however, for a single-core cable, where eddy-current heating would occur if a magnetic material was used for the armoring. The material has to be non-magnetic for armoring as in this case of return current is not passing through the same cable. Hence, it will not cancel the magnetic lines produced by current. These magnetic lines which are oscillating in case of AC systems will give rise to eddy currents in magnetic armoring and hence, armoring will become hot, and this may lead to failure of the cable. Hence, single core cables for use on AC systems are armored with single layer of non-magnetic (aluminum) material.
Armoring is mostly of following type:
• SWA – Steel wire armor, used in multi-core cables (magnetic),
• AWA – Aluminum wire armor, used in single-core cables (non-magnetic).
• Tinning or galvanizing is used for rust prevention. Phosphor bronze or tinned copper braid is also used when steel armor is not allowed.
• As strip construction is economical, the manufacture always provides steel strip armoring unless wire armoring is specified.
• As per IS: 1554 Round Wire armoring is provided in cable where calculated diameter under amour is upto13mm. Above this the amour is either steel wire or steel strip of size 4.00X0.80mm.
10. Over Sheath (Outer Jacket):
Code: IS: 7098 / IEC: 60502 / BS: 6622/BS: 7835.
Material: PVC Flame Retardant / Flame Retardant Low Smoke / Zero Halogen (LSOH), High density Polyethylene HDPE, Halogen Free Flame Retardant (HFFR)
Used for: LV, MV & HV Cables
• It is the outer protection part of the cable against the surrounding environment.
• Protected against water ingress, protection against termite, protection against UV and protection against differing soil compositions.
• It is applied over armoring in case of armored cable and over inner sheath in case of unarmored cable called as ‘Outer Sheath.’
• The standard sheath color is Black other colors such as Red, Light Blue can also be provided.
• High-voltage cables are identified by outer sheaths colored red; a black sheath indicates a low-voltage cable
The following are the electrical property may be considered while selecting an outer Sheath Materials
• Dielectric Strength: Cable Sheath may be semiconducting or insulating.
• Discharge and Tracking Resistance: When a non shielded cable rests upon or comes into contact with a ground plane, the ground plane acts as the outer plate of the capacitor, made up of the conductor, insulation and the ground plane. Discharges and tracking may cause erosion of the outer sheath material.
• Material: A major consideration in selecting outer sheath may be a thermoplastic or thermosetting material. Mostly, a thermoplastic jacket is less expensive. However, thermoplastics will melt at some elevated temperature and, thus, could run or drip from the cable under extreme conditions.
• Thermoset materials will not melt and run or drip at elevated temperatures.
Comparison of Cable
PVC Insulated Cable
• PVC insulation becomes stiff making it difficult to fold and the soft PVC loosens its softening agent over years, making it brittle and prone to rip.
• Even at the time of disposing, burning PVC emits toxic dioxin, which is responsible for causing cancer and does, when dumped scantly dissolve.
• PVC is thin insulation mainly used in LT side cables and XLPE is thick insulation used in MV & HT cables.
XLPE Insulated Cable
• Higher Current Capacity: XLPE has higher current carrying capacity.
• Higher Temperature Withstand Capacity: It can withstand higher temperature compared to PVC cable.
• Higher Overload Capacity: XLPE have high overload capacity.
• Low Dielectric Constant: XLPE has lower dielectric and constant power factor.
• Light weight & Small Bending Radius: XLPE cables are lighter in weight, has smaller bend radius, and hence lesser installation cost.
• Higher Short Circuit Capacity: XLPE has higher short circuit rating. XLPE can withstand higher & lower temperatures insulation is usually thinner but the resistance is higher.
• Higher Moisture Resistance: XLPE also has a higher moisture & chemical resistance.
• Cable installation job for XLPE is easier than PVC insulated cables because of less weight, less diameter and less bending radius.
• The volume resistivity (ohm-cm) for XLPE is way higher than the PVC cables which are of the order of XLPE cable has insulation resistance of 1000 times compared to PVC cables.
Elastomer Insulated Cable
• Elastomer cables are preferred for flexible application and in congested locations, where the bending radius are very small. Elastomer cables are available from low voltage up to 33 kV grade.
• Elastomer cables are also available with rigid copper conductors and having properties like fire survival, zero halogen and low toxicity FS properties.
Rubber Insulated Cable
• Rubber insulation remains in the best condition after a long span of time, say 25-30 years and remain soft and pliable even when the temperature is low.
• Rubber Cables are predominantly used in special applications like, mining, ship wiring, transportation sector and defense applications & earth moving machines.
• These materials have the potential to be recyclable since they can be molded , extruded and reused like plastics, but they have typical elastic properties of rubbers which are not recyclable owing to their thermosetting characteristics
Cable Selection Parameters
Voltage of Cable
• The Nominal voltage is to be expressed with two values of alternative current Uo/U in V (volt).
• Uo/U : Phase to earth voltage
• Uo : Voltage between conductor and earth
• U : Voltage between phases (conductors)
• (i) Low-tension (LT) cables — upto 1000 V
• (ii) High-tension (HT) cables — upto 11,000 V
• (iii) Super-tension (ST) cables — from 22 kV to 33 kV
• (iv) Extra high-tension (EHT) cables — from 33 kV to 66 kV
• (v) Extra super voltage cables — beyond 132 kV
• A low-voltage system usually has a solidly earthed neutral so that the line to earth voltage cannot rise higher than (line volts) ÷ √ 3. Cables for low-voltage use are insulated for 600V rms score to earth and 1000V rms core to core.
• High-voltage cables used in Shell installations are rated 19000/3300V or 3810/6600V or 6600/11000V, Phase/Phase.
• In selecting the voltage grade of cable, the highest voltage to earth must be allowed for. For example, on a normal 6.6kV unearthed system, a line conductor can achieve almost 6.6kV to earth under earth-fault conditions, to withstand this, a cable insulated for 6600/11000V must, therefore, be used.
Current Carrying Capacity
• The current carrying capacity of a cable is called Ampacity. Ampacity is defined as the maximum amount of electrical current a conductor or device can carry before sustaining immediate or progressive deterioration and is the rms electric current which a device or conductor can continuously carry while remaining within its temperature rating.
Short Circuit Values
• The “short-circuit current rating” is the maximum short-circuit current that a component can withstand. Failure to provide adequate protection may result in component destruction under short circuit conditions.
• Short circuits and their effects must be considered in selecting cables. These cables should have a short circuit rating which is the highest temperature the cable can withstand during an electrical short circuit lasting up to about half a second.
Type of Conductor
• Type of Conductor Material Copper or Aluminum is main criteria for selection of Cable
No of Core
• No of core selection is depends upon power system.
• For Single Phase Power Supply, we can use 2 core cable for three phase supply we can use 3.5 core or 4 core cable for HV supply. We may be use single core cable.
• It is a primary concern when installing lengths of cables is voltage drop. The amount of voltage lost between the originating power supply and the device being powered can be significant. All cables have resistance, and when current flows in them, this results in a volt drop.
Type of Insulations
• Type of Cable Insulation Material like, PVC, XLPE, Rubber
• PVC Cable is cheaper than XLPE Cable
Method of Installation
• If we lay cable in ground armor cable is required. But if we lay cable in cable tray, we may be used an armor cable to reduce cost of cable.
• If we lay cable on cable tray, then shielded cable is required.
• Mutual heating effect due to cable group laying is also considered while selecting a cable. When multiple cables are in close proximity, each contributes heat to the others and diminishes the amount of external cooling affecting the individual cable conductors. Therefore, cable de rating is necessary consideration for multiple cables in close proximity.
Shielded Cable or unshielded Cable
The choice of a shielded cable or non-shielded cable depends upon some criteria.
• An area such as a production/factory floor where heavy equipment being used is a prime example of a place where we might consider a shielded cable.
• Grounding can also be a concern in some installations. If shielded cable is used to connect equipment from two different circuits, a ground loop can occur, causing noise on a network line. If the ground voltage difference is great enough, it may even cause damage.
• Terminations of the shielded cable must also be made with care to provide for a smooth dielectric transition from the shielded condition to the unshielded condition.
• The substantial space required if shielded cables were used. Shielded cables require a significant amount of space at each end of the cable for installation of the stress cone kit. Also, the minimum bending radius for shielded cables is twelve times cable outside diameter, whereas the minimum bending radius for unshielded cables is only eight times outside diameter (and even less with extra-flexible appliance connection cables used in controllers).
• The two factors, high cost and large space requirements, preclude use of shielded cable in switchgear.
• It is also an important factor for selecting the type of cable.
• It is to be kept in mind that the cost of cable should not be such large that it causes loss and another cable may fetch the same results in low cost and loss.
• Cable operates at its best when it is installed in its optimum environmental conditions.
• For example, Elastomeric Cable is applied in trailing, coal cutter, wind mill, panel wiring, battery cable and such other areas. XLPE cables work good in areas where moisture content is good. Thus, proper cable should be selected so that the system becomes more efficient.
• Low voltage cables with both PVC and XLPE insulation are suitable for indoor and outdoor applications.
• Armored cables are not recommended for tray applications, as they are heavy in weight and extra loads are exerted on the tray.
• Unarmored cables are not recommended for direct buried applications, except if the quoted cables are designed and produced to pass direct burial test requirements (example, direct burial tests described in UL 1277 and UL 1581).
• A PVC jacket is a very stable material against a wide range of chemicals, while HDPE jacketed cables can serve better in wet locations.
Cable Core Colors Identification
• Single core – Natural
• Two core – Red, Black
• Three core – Red, Yellow and Blue
• Four core – Red, Yellow and Blue and Black
• Five core – Red, Yellow and Blue and Black and Green
Abbreviation for PVC & XLPE Cable
• A = Aluminum Conductor.
• Y = PVC Insulation or PVC Sheath
• 2X = Cross-linked Polyethylene Insulation
• W = Round Steel Wire Armoring
• WW = Double Round Steel Wire Armoring
• F = Formed Steel Wire (Strip) Armoring
• FF = Double Formed Steel Wire (Strip) Armouring
• C = Metallic Screening (Usually of Copper)
• CE = Metallic Screening (Usually of Copper) over each individual core.
• Gb = Holding Helix Tape (of Steel)
• Wa = Aluminum Round Wire & Aluminum Formed Wire (Strip) Fa Armouring.
• AYY: Aluminum Conductor, PVC Insulated, PVC Outer Sheathed Heavy Duty Cables.
• AYWY: Aluminum Conductor, PVC Insulated, Round Steel Wire Armored and PVC Outer Sheathed
• AYFY: Aluminum Conductor, PVC Insulated, Flat Steel Wire (Strip) Armored and PVC Outer Sheathed
• AYCY: Aluminum Conductor, PVC Insulated, Metallic Screened and PVC Outer Sheathed
• A2XCY: Aluminum Conductor, XLPE Insulated, Metallic Screened and PVC Outer Sheathed
Cable Application Standard
• IEC 60502 (Part 1)”PVC/ XLPE insulated cables” single core /multi-core
• BS 5467 for XLPE insulated armored cables
• BS 7889 for XLPE insulated single core unarmored cables
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