DIN EN 60947-7-3:2010-05

This standard specifies requirements for fuse terminal blocks with screw-type or screwless-type clamping units for the connection of rigid (solid or stranded) or flexible copper conductors for the reception of cartridge fuse-links in accordance with IEC 60127-2, intended primarily for industrial or similar use in circuits with rated voltages not exceeding 1 000 V a.c., up to 1 000 Hz or 1 500 V d.c., and having a maximum short-circuit breaking capacity of 1 500 A. They are intended for installation in electrical equipment with enclosures which surround the fuse terminal blocks to such an extent that they are accessible only with the aid of a tool. This standard on fuse terminal blocks does not only contain the requirements for terminal blocks for attaching them on mounting rails but also takes into account the specifications for cartridge fuse-links in accordance with IEC 60127-1 and IEC 60127-2. The two standards are linked by adding (adapting) the basic specifications for cartridge fuse-links (rated current, rated voltage, maximum voltage drop and maximum power dissipation of cartridge fuse-links with dimensions of 5 mm×20 mm or 6,3 mm×32 mm with their different tripping characteristics) to the requirements of IEC 60947-7-1 for terminal blocks. Thus it is possible to assess the quality of the product "fuse terminal block". It is one important fact that fuses heat up much less at rated load than at overload when using such cartridge fuse-links for fuse terminal blocks. The rated load is determined from the rated current and the maximum voltage drop. However, considerably higher power dissipation occurs at overload, which is equal to the maximum power dissipation according to IEC 60127-2. In industrial applications, an arrangement consists of either individual fuse terminal blocks in combination with terminal blocks or high numbers of only fuse terminal blocks. This means that the same current and fuse link lead to different heat dissipation. It should be also taken into account that independent of the general full range fuse (for overload and short-circuit protection), some fuse terminal blocks are used only as short-circuit protection according to IEC 60364-443, for instance in control circuits, where no overload occurs (for instance coils in safety circuits, illuminated displays or similar equipment). Consequently, there are four different application quadrants, which shall also be described in the catalogues or indicated on the fuse terminal blocks. With respect to DIN EN 60947-7-3 (VDE 0611-6):2003-07 the following changes have been made: - the requirements for clearances and creeping distances have been replaced by a reference to Annex H of EN 60947-1; - the requirements for the test of mechanical strength of the clamping units in 8.3.3.1 have been improved; - the torque test specifications have been improved and a reference has been made to Table 4 of EN 60947-1; - the requirements for the resistance and the dimensions of the dummy fuse links have been specified in 8.5.2.5. At DIN and VDE the responsible Committee is K 431 "Niederspannungsschaltgeräte und -kombinationen" ("Low-voltage switchgear and controlgear assemblies") of the DKE (German Commission for Electrical, Electronic and Information Technologies).