Fuse bases are used for mounting fuse-links with knife contacts. In conjunction with a fuse link, they form an electrical apparatus in which the melting of a certain element causes a circuit break. In this way, people are protected against electric shock, and devices and circuits - against the harmful effects of overcurrents. The fuses also prevent fires caused by a faulty electrical system.
Fuse bases are equivalents of fuse bases in low voltage and high power circuits. Together with the replaceable fuse links and the handling part, they form elements of the standardized NH system (German Niederspannungs-Hochleistungs-Sicherungen ).
The fuse bases are not standalone devices but connecting elements between the wiring and the fuse links. The installation of the fuse link in the base creates the current path of electric power distribution devices in electrical industrial installations.
Under normal operating conditions, the current flows through the fuse-link and the base contacts. In the event of a short circuit or overload, the current exceeds the permissible rating and the fusible link begins to melt. When completely melted, the circuit is broken. In this way, the fuse prevents the effects of overcurrents. After the fuse has been destroyed, the fuse link cannot be reused and must be replaced, while the base, provided it is not damaged, can continue to perform its function. The fuse bases are manufactured in a traditional form, intended for horizontal installation on rails or on the mounting plate of an electrical cabinet, and as vertical, strip bases.
Conventional fuse bases are a fixed part of an industrial fuse, which has been adapted to attach a knife fuse and thus insert it into the current path of power distribution devices. Manufacturers who offer NH fuse bases provide the appropriate electrical parameters in various ways, however, due to proven methods, fuse bases of known brands do not differ significantly from each other, therefore they can be taken as representative production bases of Apator type PBD .
PBD bases are made of flame retardant polyester-glass plastic, while their contacts - of electro-galvanized copper or optionally silver-plated copper (the largest bases are always silver-plated). The working conditions of PBDs must meet the following requirements:
The strip fuse bases were created in response to the demand due to space saving in industrial switching stations. Compared to typical fuse bases, their strip counterparts take up less space because they are implemented vertically, using the space between the busbars. Apator products, which are representative of this type of bases, provide the possibility of connection with a screw clamp, bridge clamp and clamp and are made of flame-retardant plastic (polyamide, halogen-free polyester) reinforced with glass fiber. Some fuse bases can be equipped with single fuse-link covers with IP20 protection.
