Enamelled Aluminium winding wire is an integral part of a winding coil in every electrical machine or apparatus, mainly in application such as transformers, chokes, motors, pumps, electro-magnets, electro mechanical relays, automotive alternators and cut-outs, etc. Compared to fibrous insulations, enamelled aluminium wire offers a favourable space saving factor together with a high level of breakdown voltage. Like other wires, enamelled aluminium wire is classified by diameter (AWG number or SWG) or area (square millimetres), temperature class and insulation class.

Application of Enamelled Aluminium Wire:

The P-LINE range of enamelled aluminium wires are primarily used in three types of applications as in Transformers to transform one kind of electrical energy into other kinds, in Motors to transform electrical energy into mechanical energy, also used in Generators to transform mechanical energy into electrical energy. Enamelled aluminium wire, also called "Magnet Wire", is widely used in various electrical applications due to its superior electrical, thermal and mechanical properties. Enamelled aluminium wires are used in Electro-Magnets to generate a magnetic field through electricity.

Round enamelled aluminium wire is an excellent electrical conductor, and consequently have a wide variety of applications, including use in automobiles, electric motors, distribution transformers, dry-type transformers, electro-magnets, inductors, relays, micro-motors, air-conditioners, precision electric appliances, deflection coils, audio devices, buzzers, microphones and industrial machinery. The wire is also found in smaller devices and home appliances, such as computers, televisions, etc. For ease of manufacturing inductive components like transformers, chokes and inductors, most of these wires can be soldered/welded.

Connecting of Terminals

Problems of connecting aluminium wires to the terminal never affect the motor design, where connections are made with equipment suitable for the purpose. Manufacturers use oxide-piercing connectors and specialized, high-pressure connector crimpers to create a uniform, high-conductivity connection which virtually eliminates the possibility of oxide affecting the integrity of the connection. They have found that it is critical to motor reliability to have the right connection design, materials, and manufacturing processes.

Suitability in adverse applications

Motor manufacturers have conducted extensive study on the impact of adverse environment on aluminium magnet wire. These studies have centred on some of the more challenging applications, such as domestic water pumps (where the motor windings are subjected to mineral salts) and pool pumps (where the windings must withstand chlorinated water). Aluminium is well-suited to adverse environments and is used, along with copper for magnet wire, in many motors.

Advantages and benefits

Aluminium is 3 times lighter than copper by consequently reducing the weight of the product in which it is used as well as reduction in the cost of freight and transportation, cost effective and user friendly. It has high electrical conductivity, better heat dissipation, and excellent insulation/enamel, for a longer life with hard oxide coating on surface, for easier coiling. Resistance of heat temperature is higher by 20?C than copper, allowing aluminium to withstand better current overloads. Production and handling cost can be commendably reduced. Enamelled aluminium winding wires are fast replacing copper, since it is more affordable comparatively. Today most of the manufacturers are opting to use aluminium winding wires to sustain the competition.

Insulation - Enamel/Varnish

Modern Enameled Aluminium winding wires are typically insulated with a thin layer of enamel/varnish (Polyurethane/Polyester) often with one or more different compositions, to provide a tough and continuous insulation layer. Insulation varnish coatings of different temperature classes (in order of increasing temperature range) are used to prevent short circuit of the wire surfaces when wound into coils. Magnetic flux is created when current flows through the coil. The smaller these devices are, the stronger they are because Enamelled aluminium wires are insulated by a thin coat of enamel instead of other types of thicker insulation like paper, fibre-glass and mica, etc. The polyester insulating varnish commonly used on a motor's magnetic wire has a copper like hue. This makes it almost impossible to distinguish the material used in the motor windings. Other than understanding the application and the limitations of aluminium, you typically have no way of knowing if you have a motor with aluminium or copper winding.

As enamel aluminium wires take up less space in coil formation so it makes more effective and compact coils with higher efficiency. Breakdown voltage of aluminium enamelled winding wires depends on the thickness of the covering, which can be of 3 types: Grade 1, Grade 2 and Grade 3. Higher grades have thicker insulation and thus higher breakdown voltages. The temperature class indicates the temperature of the wire where it has a 20,000 hours service life.

At lower temperatures the service life of the wire is longer (about a factor 2 for every 10?C lower temperature). Common temperature classes are 130?C (B Level), 155?C (F Level) and 180?C (H Level). Insulation Class 'B', 'F' and 'H' are for application such as dry type transformers, stator winding fractional HP motors, DC field and armature windings. Polyester coated wires have very good chemical resistance and are compatible with all general purpose impregnating varnishes including high temperature modified phenolic polyester and others which do not contain the reactive solvent.

Conductivity

Enamelled aluminium winding wires are widely used in electric devices because of their excellent conductivity. Aluminium enamelled wires are meant to carry electrical currents more efficiently. Transformers made of enamel aluminium wires have lesser energy losses and higher heat dissipating factors.

Resistance to Corrosion

The third feature of enamelled aluminium wires that make them so attractive for use in these devices is its resistance to corrosion. Enamelled aluminium wire is the material of choice for use in electrical circuits, as it lasts for a long time. The mech- anical, electrical and chemical characteristics of enamelled aluminium wire differ from those of copper magnet wire because of the inherent differences in the conductor materials. These differences are reflected in certain test procedures and/or performance requirements for aluminium enamelled wire, such as elongation, adherence and flexibility, heat shock, scrape resistance, continuity and thermal endurance. Smaller diameter magnet wire usually has a round cross section.

Performance Features of Enamelled Aluminium Wires

Enamelled aluminium winding wires are resistant to high temp- eratures, suitable for high-speed automated winding/routing, excellent performance at breakdown levels, can be directly soldered/welded, with no pinhole, resistive to high frequency, wearing, refrigerants and electronics corona, high breakdown voltage, low dielectric loss angle, dozens of times on pulse life as the ordinary compound enamel-insulated wire Reference Standards: NEMA MW1000 -1997/IEC- 60317/JIS-3202. The wire is available in gauges from SWG 38 - SWG 13.

Garg Distributors Private Limited, Hyderabad. Tel: 040-23074040, 23074050. Mobile: 099481-23466. Email: keshav@gdpl.info, garg@gdpl.org