Stranded wire
The braid (English stranded wire ) is a thin individual wires from existing and therefore easy to be bent electrical conductor in electrical engineering. In electrical cables, copper is used as a conductor mainly. In technical terms denote electrotechnical standards (eg IEC 60228 / VDE 0295 ) for the distinction of inflexible single wire or stranded wires these wires as "fine or extra fine head ".
Thin insulated wires are also known as aerial wire. In high- frequency litz wires (HF litz wire) the individual wires are insulated from each other by a layer of lacquer, although they carry the same potential. Thus, the influence of the skin effect can be reduced or avoided in the high-frequency technology - otherwise only a small part of the total cross section would participate in the current transport.
A Braid is a mesh of Litzenstücken to clean the thermal dissociation of solder joints ( absorption of the liquid solder by capillary action ).
General
The individual wires of the strand (up to several hundred) are usually enclosed in a common insulating sheath. Such hot conductor stranded. If several such lines together in a cable, they are called veins.
Since the risk of a conductor breakage due to bending with stranded wire is much lower than with solid wire conductors with same cross section, they are used primarily where a common movement or vibration stress takes place (machinery, vehicles and planes, robots) or when a mobile device must be powered ( hand-held electric devices, plug-in power cables, microphone and speaker cable). Depending on the required flexibility and stress level using fine or superfine stranded conductors.
To connect the stranded wires in terminals usually need to be fitted with ferrules to connect all the individual wires safely and protecting them with the locking screw from mechanical damage. In the constructions lift clamp and spring clamp terminal can be dispensed with a ferrule. To attach wires also to cabinet doors (PE for grounding ), this vein is provided with a cable lug. Naturally lugs are used for various other compounds.
Assembled with cable lugs superfine strands serve as a so-called ground wires to grounding of, inter alia, of the cabinet doors. As a ground wire but also in high voltage overhead lines at the top implemented, being at ground potential lines are referred to in the interest of lightning protection. Overhead lines are also mostly made up of several individual wires, but are not referred to as wire, but as the head rope.
Tinning clamped wire ends has proven to be unreliable because of creep of the soft solder and its poor contact properties (oxidation) to loosen and break or to a high current density in the terminal and ultimately may lead to an arc with the result of fire damage. A fault arc protection device in the sub-distribution can prevent consequential damage caused by loose terminals and resulting arcing faults at higher operating currents.
Strands are used for the production of coils. The higher the surface to be used, the higher the quality of coils.
*) Resistance is calculated with spec. Resistance 0.0172 ohms * mm ² / m for typical electric copper "E - Cu 58 ". - ) Max. permissible current density of 10-15 A / mm ² at d = 2 to 0.5 mm (DIN VDE 0891 and VDE 0100 T.1 T.523, 1981-06 Group 2 ) - in brackets: as max. Operating current density at superfine fibers is 3.6 A / mm ² called, -. Extrapol / calculated values in italics.