Mandatory basic protection in electrical installations
Overcurrents in electrical systems occur as a result of overload or due to short-circuits, and can cause serious accidents, fires and financial losses. Corresponding protection equipment has therefore been mandatory since electricity was first used in power engineering. As a pioneer of fuse systems, we offer you the complete range of devices for protecting cables and electrical devices and systems in case of overload and short-circuit.
Short-circuit and overload protection
Overload currents can occur in a fault-free electrical circuit if the permissible current loading is exceeded due to an operation or the simultaneous operation of several consumers. Short-circuits on the other hand are conductive connections occurring as the result of a fault, for example between phase and neutral conductor. Short-circuits in electrical systems generally occur suddenly and involve extremely high power which is explosively discharged. In case of overload currents and short-circuits cables can heat up as a result and set fire to installations or entire buildings.
International standards and building regulations therefore stipulate suitable measures for protection of electrical equipment against overload and short-circuit – with good reason.
Fuse systems – versatile in use
Fuses disconnect the circuit safely as soon as an overload or short-circuit occurs. This prevents damage to electrical equipment and reduces downtimes. Specific variants of fuse systems are used for different applications.
One of the most common application areas for fuse systems is protecting cables and lines against overheating. Utilization category gG has been standardized for this. Fuses with utilization category gG are matched in their time/current characteristics to the maximum permissible load of insulated cables. gG fuses also protect electrical systems and devices and can be employed for backup protection of components such as residual current circuit-breakers, miniature circuit-breakers and molded case circuit breakers.
Fuses have proven themselves as particularly economical and reliable short-circuit protection equipment in motor circuits. Compared with other protection devices, fuses have considerably lower cut-off currents and values. As a result, there is hardly a more affordable method of providing short-circuit protection in accordance with VDE 0660 coordination “2”.
Fuses of different utilization categories and technical parameters are employed for the protection of semiconductors, depending on the place of installation and required degree of protection for the power semiconductor used (diodes, thyristors, GTOs, IGBTs, etc.): Partial range fuses of utilization category aR provide protection against short-circuits, and full range fuses gR and gS against overload as well. Fuses of utilization category gS additionally fulfill the requirements for protecting leads and cables in case of overload, in other words they combine semiconductor and cable protection.
Particular risks to photovoltaic systems are so-called reverse currents, which can occur in the event of faulty solar modules. Among other measures, special fuses with full range characteristic gPV designed to meet the characteristic requirements of photovoltaic systems are needed to protect such systems. The same applies for wind power plants. In this case, gG fuses are generally used for which, however, separate tests must be conducted to verify conformance with the special requirements (e.g. higher network voltage tolerance).
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Basic protection against short-circuit and overload
Fuse systems are a permanently established element of power distribution systems for applications in infrastructure, buildings or industry. They provide fundamental protection in a wide range of different fields of application and disconnect reliably in the event of short-circuit or overload. Be sure to explore our portfolio.