Paper Wrapped Wire for High Power Transformers, A Growing Demand for African Countries in General and North Africa in Particular

August 04 20:16 2022

Transformer windings are made primarily of copper, and they are usually insulated with paper. Copper has made possible much of today’s electrical industry because, in addition to these excellent mechanical properties, copper has the highest conductivity of the metals. Its importance in transformers is particularly the minimization of load losses compared to other metals.

To produce a transformer winding with a given nominal voltage and a defined number of turns, two winding technologies are possible: battleship or column.

Each of them is characterized by its configuration of windings with respect to the magnetic circuit. The so-called battleship technology consists of placing the coils in the center of the magnetic circuit. In column technology, it is the opposite.

Each of them has its advantages which can be:

• space saving (battleship) • better short-circuit resistance (battleship) • better cooling (layers) • better resistance to lightning shock (layers) • a ease of production and good dielectric strength

Battleship type :

In battleship technology, the magnetic circuit surrounds the high and low voltage windings of a given phase, as shown in the figure below.

In these armored transformers the return paths of the magnetic flux through the magnetic circuit are external and surround the windings. Thanks to its excellent arrangement of magnetic shielding, the armored transformer is particularly suitable for the supply of low voltage and high current, as for example in the case of arc furnace transformers.

This technology is particularly compact compared to column technology. However, it requires some experience and a lot of labor in the construction of the windings and the assembly of the tons of magnetic circuit.

Column type:

Column type transformers have their magnetic flux return paths passing through magnetic circuit legs which are concentrically surrounded by the main windings, as shown in the figure below.

In a three-phase transformer there is one magnetic circuit leg per electrical phase. This type of transformer is particularly widespread in the world for any type of application.


Standard TUN 900.031: Insulated flat wires for winding, covered with paperStandard TUN 900.032: Insulated round wires for winding, covered with paperStandard TUN 900.114: Disposable container for paper-insulated round wiresStandard DIN 6740: Paper for electrical useStandard IEC 60554-1: Specification for cellulosic papers for electrical

Insulated flat wires for winding, wrapped with paper:



For the conductors, copper E.CU 58 F20 (E-CU) is used according to the DIN 40.500 standard (4th part). It is the same type of copper that is used in electrical cables.


Cellulosic paper:

The type used is: type P 5238 according to standard DIN 6740 or type D according to standard TUN 901.155The flat wires are insulated, wrapped with three layers of paper overlapping each other.The paper insulation must be smooth and without voids; it must not have any cracks or holes that could impair use. The different layers must be contrasted and overlap by at least 15% but not have less than 2.5mm.

In addition to paper-insulated flat wires, transformers are also made of round-section copper wires insulated with varnish.

Paper-insulated flat wires are most often used for medium and large power transformers and enamelled round section copper wires for small power transformers

All these products are in great demand in the countries of North Africa, whether in Algeria, Tunisia, Morocco and all the other countries in the region.Energy needs are increasing exponentially in this vast region of the African continent, so it is quite natural that the needs for small, medium and large power transformers are also increasing very significantly.

For all these very important projects economically for the countries concerned, LINT TOP CABLE TECHNOLOGY CO., LTD as well as its branch ONE WORLD CABLE MATERIALS CO., LTD. provide very complete and very effective solutions with regard to production and test equipment as well as all the raw materials necessary for this production.

Indeed, concerning production equipment in the first place, LINT TOP CABLE TECHNOLOGY CO., LTD provides the best of Chinese origin, of very high efficiency and profitability:

VERTICAL TYPE ENAMELING MACHINE for round section copper enameled wires with diameters Ф0.80mm ~Ф2.50mm. – VERTICAL TYPE ENAMELING MACHINE for round section copper enamel wires with diameters Ф0.80mm~Ф2.50mm, – LT300 Continuous Extrusion Production Line for Copper Strip with a Minimum Cross Sectional Area of 5mm2, a Maximum Cross Sectional Area of 150mm2, a Maximum Width of 30mm with an Average Output of 480kg/h, and finally our – PAPER WRAPPING MACHINE with two paper tapping heads, each taping head may wrap 4 layers of paper, so it can wrap Max.2*4=8 in total and with three paper layers.

All this combined equipment ensures the production of the full range of enamelled wires with round sections as well as paper-insulated flat wires used for the copper windings of motors and small, medium and high power transformers.

And as the strategy of LINT TOP CABLE TECHNOLOGY CO., LTD has always been to present all its customers with the most complete solutions in their various projects, ONE WORLD CABLE MATERIALS CO., LTD branch of LINT TOP CABLE TECHNOLOGY CO., LTD ensures the supply of the raw materials necessary for the production of enamelled round copper wires and paper-insulated flat wires, namely copper, varnish for insulation of round section wires as well as any type of insulating paper of very good quality and presenting the best electrical and mechanical characteristics necessary for the insulation of flat wires.

Investors interested in this field of production currently in high demand, particularly in North Africa, can count on LINT TOP CABLE TECHNOLOGY CO., LTD and its branch ONE WORLD CABLE MATERIALS CO., LTD to support them in their projects by providing all the necessary equipment and raw materials and supporting them technically in all aspects.

The customers of LINT TOP CABLE TECHNOLOGY CO., LTD and its branch ONE WORLD CABLE MATERIALS CO., LTD are certainly in good hands, they can count on us as usual.

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