Competence
Distribute - Switch - Protect

In low-voltage technology, electricity is carried through a large number of specific components such as cables, rails, power distribution components and the corresponding connections and terminals. But even within devices, the power must be routed via internal busbars or cabling and connected to other parts. Every current-carrying electrical conductor has an electrical resistance, which leads to heating. This must be observed in accordance with the further mechanical and electrical requirements and the conditions of use and may place additional requirements on the current-carrying part or surrounding materials.

In addition, every connection of two current-carrying electrical conductors is a contact point with an additional contact resistance. A distinction is made between permanent contacts that cannot be detached, such as crimp, solder and weld connections, and detachable contacts, such as plug, clamp and screw connections. Environmental conditions and the material pairing can lead to corrosion, which can lead to an interruption in the power supply or to melting. This must be taken into account when designing and dimensioning the material pairing; a surface treatment (tin-plating, silver-plating, gold-plating) may be necessary.

The occurrence of an electric arc during a switching process requires a minimum current intensity and a minimum voltage. Current strength and voltage depend on the contact material. In the case of high service life requirements, for example in relays, one tries specifically to avoid an electric arc. However, an arc also enables dirt on the contact surfaces to be broken up. If there is no arc, other technical solutions such as friction and rolling contacts or hermetically sealed chambers must be used in order to avoid contact problems and achieve a high level of contact reliability.

In higher current and voltage ranges, the breaking arc is used specifically as an aid for the switching process and fulfills an important technical function. The mechanisms, switching chamber, contacts and materials must be designed and optimized in accordance with the areas of application and the breaking capacity to be achieved. At high rated outputs, this leads to complex extinguishing chamber geometries with perforated plates, blow magnets, hard gas elements and flow-optimized discharge geometries. In addition, the arc leads to considerable contact erosion and thus wear to the contacts.

In return, the pre-ignition arc with its risk of contact welding and material migration must be controlled when switching on.

In addition to contact-based switching, semiconductor components such as thyristors also enable contactless switching. In the case of so-called hybrid switches, a contact is first switched off contactlessly and then a switching contact is opened without current to ensure an isolating distance.

The insulation coordination is necessary for all electrical devices, products and equipment. On the one hand to ensure the correct functioning, on the other hand to guarantee the safety of the user or application. The technical requirements are defined by the conditions of use (degree of pollution and overvoltage category). Compliance with creepage and clearance distances must be taken into account early on in a design, as this has a significant influence on the technical implementation of solution principles.

The triggers are often simple mechanical meanisms based on thermal bimetals, solenoids, piezo actuators or shape memory elements. In addition, there are springs as energy stores and levers and translations for coordinating forces and paths. The construction of such mechanisms requires a high technical understanding of the basic physical principles - but often just a lot of attempts and tests to adjust and optimize the respective application limits.