EoW November 2009

Power cables

Power cable marking There are two types of colourless embossing suitable for medium to high voltage cables: raised and indented embossing. Raised embossing uses an embossing wheel with engraved embossing dies, or ‘segments’, attached to it, that roll along the hot, soft cable sheathing material immediately after extrusion, leaving a marking on the surface of the cable in the form of raised lettering. Indented embossing is usually carried out on a cold cable surface using heated embossing wheels with raised engraving. Indented embossing cannot achieve such high production speeds as raised embossing, as it involves the use of heated embossing dies that require the transfer of heat to the cable sheathing material.

Many cable embossing machines can also be used to mark up continuous lengths (number of metres), and are therefore equipped with embossing wheels with a one-metre circumference. The embossing wheel contains a counter – usually with four or five digits – that increments with each revolution of the marking wheel so as to apply a consecutive metre reading to the cable sheath. A reset mechanism makes it possible to reset the metre counter quickly and easily, for example when a new cable reel is fitted to the winder. The marking wheels of all standard KMS Series cable embossing machines from Medek & Schörner are fitted with a metre counter with a manual reset and two segment clips. In accordance with the standard, these are used to apply marking text to the cable sheath at distances of half a metre. The metre counters can also be pro- vided with an electro-pneumatic reset mechanism that can be synchronised with the winder in such a way that it is reset

ICS embossing unit with concave, water-cooled embossing wheels for marking cables on two sides ▲ ▲

precisely where the cable end is cut. The accuracy of length marking depends on many factors including slippage between marking wheel and cable surface, deformation of the cable during the embossing process and subsequent shrinkage of the cable. Medek & Schörner offers auxiliary drive units that can compensate for slippage, or can be synchronised with great accuracy with a revolution counter or any other type of transducer. This makes it possible to reduce measuring errors to less than 0.1%. Some cable standards prescribe the embossing of cable sheaths on two sides, though no length marking may be required. For such applications, Medek & Schörner offers the ICS series, which apply marking to the hot cable sheath immediately after the extruder using embossing wheels with recessed engraving. Cooling the embossing wheels with water prevents them from sticking to the soft insulation. These machines also offer a wide range of marking fonts using easily exchangeable embossing dies. Medek & Schörner – Austria Fax : +43 1982 7296 Email : m+s@medek.at Website : www.medek.at

Producing electrical cable

Standard sizes for 800kg, 1,500kg or 2,000kg pull are available from stock. Also available are used and reconditioned cable- makingmachines, which can be modernised and finish- ed with new components according to the customer’s specifications. Queins & Co – Germany Fax : +49 2472 3014 Email : info@queins.com Website : www.queins.com

Queins & Co GmbH produces heavy-duty stranding and cabling machines, and a range of rigid, skip-type and tubular stranders, planetary stranding and armour- ing lines, drum twisting lines and bow stranders for the production of medium to extra-high voltage cables, offshore and umbilical cables. Suitable capstans and taping heads are also available, and CTCmachines for continuously transposed conductors. Payoff and take-up stands capable of carrying up to 300 tons drum weight, and caterpillar capstans with up to 15 tons pull can also be supplied.

Special rotating belt caterpillar with a contact length of 4,900mm ▲ ▲

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EuroWire – November 2009