Wires and Cables1

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Wires and cables

Shielded Wires

A shielded wire is a type of electrical wire made of several layersof covering and conductors. It is useful for different types ofapplications where protecting covering of conductor is needed.Due to the specific characteristics it has found varieties ofapplications in different fields. It shows preferable electricattributes. Each of its cores is protected and the ground wire isclosely contacted with the shield layer.

Construction of Shielded Wires

A shielded wire must have a protecting coat of layer outside it. Ithas a central core and an insulationlayer provided. Then there is a shield layer which separates the

insulation layer from a ground wire. This layer is made by a

composite tape having a metal surface along with an adhesive

surface. The metallic surface of the wire is longitudinally folded so

that it can cover a portion of the adhesive surface. Then this tapeis helically binded with the folded layer on the outer cover so that

to form alternate helical patterns of the metal and adhesive

layers. A sheath is used to wrap the shielded layer and the ground

wire. After it the sheath layer is attached to the adhesive layer

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while the ground wire remains in touch with the outer metallic

layer. The metal surface used inside makes the shield.

Metal Wires

A metal wire is generally circular in cross section and is flexible.

Most metal wires are made of several small twisted or wovenstrands available in varying lengths and diameters. These wiresare often insulated carrying current and conducting electricity.

Wire Production MethodMetals wires for various applications are processed and reducedto the desired diameter and properties by repeatedly drawing itthrough smaller dies, or traditionally through holes in draw plates.

The wires are heated in an inert atmosphere for softening andthen they are cooled, this process is commonly known asannealing. An inert atmosphere prevents oxidation, althoughsome amount of scaling always occurs and is removed by'pickling' before the wire is redrawn.

Electrical wires are covered with different insulating materials,including plastic or rubber-like polymers. Two or more insulatedwires are again wrapped in a concentric manner and wrappedwith paraffin for further protection. Wire insulation and jacketing

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is done by making them pass through extruders. There aredifferent methods and materials used for manufacturing differenttypes of wires.

Thermostat Wires

Thermostat wires or cables are used to connect a thermostat tothe cooling, heating, and ventilating system. They are used for

joining heat pumps, air conditioning controls, thermostats,heating controls and bell / alarm systemstoo. The thermostat wires are general purpose multi conductorlow voltage control cables. They come in different varieties andare generally numbered or colored to do the correct installation.

There are various types of controls and components in athermostat and the wires for these controls run into thethermostat. The wires are multi-colored. The controls are usuallycomplex and in order to run properly each wire must go to thecorrect terminal on the thermostat otherwise it will not workproperly.

Construction of Thermostat Cables

Thermostat cables are usually made of a solid uncovered copperconductor. Mostly copper is used in these applications. Then it isinsulated with polyvinyl chloride (PVC). The insulationis done without filler and it is surrounded by a fire and sunlight

resistant PVC jacket.

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Winding Wires

Winding wires are among one of the most important types of wireused in electrical industries. They are used in the production ofvarious types of electromagnetic devices like generators,transformers, pumps, control devices and motors. Though a lot ofmaterials are available and suitable for constructing winding wiresbut copper is the most widely accepted metal for it.

Winding wires are either enameled or coated with various typesof varnish and other insulating materials.

Copper is the most common conductor used in winding

wires. It may be either solid or stranded. It offers very low

resistance. The insulation used in these winding wires are made

of special and tough grade polymer compounds. These materials

make the wire impervious to water, oil, grease, and chemicals.

Applications of Winding WiresWinding wires are applied in several industries. They are used as

very fine wires in electronics and telecommunications

applications. Winding wires are used as large insulated and

covered wires for large motor and power transformation

industries. The use and demand of winding wires are increasing

rapidly as the economy of developing countries as well as the

developed countries are recovering and surging. So the demand

for electricity as well as winding wires is rapidly increasing inthese nations. Some of the most important industries where

winding wires are used are:

Automotive Domestic appliances

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Electrical rotating machinery Transformers Other electrical equipment

Varnishing of Winding Wires

Varnishing of winding wires provide a layer of insulation on thesewires. The varnishes must have the capability to resist hightemperatures. The winding wires are generally composed of aconductive material which is usually copper. This conductor iscovered with one or more layers of varnish. Varnishes arecomprised of a copolymer which is obtained from a thermoplasticor thermosetting resin. These layers can withstand temperatures

up to 200C. The resin is made of any of the followings materialslike

Polyamide imide (PAI) Polyester imide (PEI) Polyimide (PI) Polyester (PE) Polyurethane (PU) Polyvinyl acetal (PVA).

Need of varnishingVarnishes add an extra stability and strength to the windingwires. They improve their ability to withstand partial dischargesand voltage peaks at very high temperatures. These insulatedvarnished winding wires are used in the manufacturing of coils forvariable frequency controllers and converters.

Winding Wire IndustryWinding wire is used as semi finished material for generatingelectromagnetic fields and transforming electrical energy. Theindustry of winding wire is a mature industry and its market is onthe rise. Its use in making different types of electromagneticdevices make them one of the important wires in the electricalindustry. The motors, transformers, and generators are the

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building block of any type of industries, plant or systems. So theiruses in diverse areas are spreading its market by leaps andbounds.

Double Insulated Submersible Pump MotorsWinding Wires

The double insulated winding wires are used for the purpose ofwinding & re-winding of submersible pumps motors. Theespecially double insulation of wires is to operate the submersiblepumps motor under water over long periods.

Flat Cables

Flat cables, sometimes also known as ribbon cables, are a wellknown name in the field ofelectronics industry. They are used tointerconnect the inner electrical systems especially in computersto connect peripherals. As these cables are flat, they distributethe mechanical load over the total width of the cable. Flat cableshelp them to increase heat dissipation and thus eliminate theneed for large conductors.

Flat ribbon cables consist of highly stranded, individuallyinsulated conductors that are laid parallel and then fused in a flat,flexible ribbon form. These flat cables don't need repetitiousinsulating material like the traditional round wire cables. Theelectrical characteristics like capacitance, impedance, attenuationremain uniform because of the uniform geometry in these cables.

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Construction of Flat cables:Flat cables are typically made of plastic substrates. They have a

number of electrical conductors fixed to the plastic substrate.There may be 3 or 4 conductors to more than 50 conductors in asingle cable. The axial distance between the adjacent conductorsis usually 0.05 inches. The combination of substrate and plastic isflexible and flat. The width of conductors varies according to thedevice requirement.

Plastic substrates are made from different types of plastics. Theyare:

Polyvinyl Polyamide Plyetherimide Polyethylene Naphthalate Polycarbonate

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