RAST connector
RAST connectors are connectors of the so-called “household appliance standards” RAST 2.5 and RAST 5. The abbreviation “RAST” or, more precisely, the acronym stands for “Raster connection plug technology”, the numbers for the millimeter distance between the contact centers.
Origin of the RAST connectors
The household appliance specification RAST was brought into being under the umbrella of the ZVEI by a working group of manufacturers of large household appliances and connectors. In close cooperation between the most important German home appliance manufacturers Bosch and Siemens Hausgeräte ( B / S / H / ), Miele , AEG (today Electrolux ), Bauknecht (today Whirlpool ) and the connector manufacturers Wieland Electric , Lumberg , AMP (today TE ), Stocko , Grote & Hartmann (today Lear ) and Molex a standard that is still in use today was created.
Development goal of the RAST connector
The aim was to standardize the components, to guarantee the conformity of the connectors from different manufacturers and to exclude errors in the production process due to incorrectly plugged connections, or to simplify assembly when assembling the end devices and to minimize incorrect wiring. RAST also enables the grouping of connections, whereby the use of individual connections and individual cable harnesses can be avoided. Today, RAST connectors have long been the standard for a variety of sensor, switch, actuator and motor control cables that can be connected directly or indirectly to the circuit board or the components. The advantages of the RAST connector have also been recognized by other industries, so that a steadily growing worldwide distribution can also be found outside of household appliances, for example in heating technology or the automotive industry.
Areas of application
Household appliances , which are commonly referred to as "white goods", are a key segment in the consumer goods market. These include a variety of devices, e.g. B. washing machines and dryers, refrigerators and freezers, dishwashers and stoves or microwaves and the small appliances to which z. B. Coffee machines, toasters, blenders, vacuum cleaners and razors count. These strongest consumer goods with a significant electronic share are still often designed and manufactured by branded goods manufacturers in Europe.
development
The RAST 2.5 plugs have open contacts next to one another , i. H. the contacts are not separated in individual closed chambers, as is the case with the RAST 5 connector. To higher voltages, e.g. B. 250 V , via the RAST 2.5 connector, it is also possible to equip every second grid step - a RAST 2.5 connector can then also be a 5 mm connector. Initially there was a clear separation between the connectors according to RAST 2.5 for signal and low load currents, e.g. B. of up to 4 A and the power connectors according to RAST 5 for the range z. B. up to 16 A, which has been softened by device manufacturers over the years. More and more attempts are being made to replace the relatively large RAST 5 connectors with RAST 2.5 - for example, to make the circuit board of a washing machine control more compact and therefore cheaper. This trend led to the development of a more powerful connector for higher voltages and currents, but which should have the proven features of the RAST 2.5 series. This meant in particular the coding, the use of a housing for direct and indirect mating and the external dimensions of the mating face.
They were looking for a connector that looks like RAST 2.5 but can carry higher currents. The somewhat larger contacts required for the higher current carrying capacity - as with the RAST 2.5 / 250 volt application - led to a 5 mm pitch. This series is u. a. Called RAST 2.5 Power, after all, the mating connector is a RAST 2.5 pin header and not a RAST 5 header, or a RAST 2.5 guide frame when it is plugged directly onto the circuit board. Meanwhile, RAST plugs with a contact spacing of 7.5 mm are also on the market, which have been developed based on the RAST 5 standard. These connectors, which can also be coded, are designed for even higher voltages and currents up to 500 V and 25 A, as required in electric vehicles, for example . While the previous series had different contact carriers for direct and indirect plugging, the RAST 2.5 connectors were designed in such a way that they can be plugged indirectly onto pin headers as well as directly onto the edge of a circuit board. However, since this form of direct plugging requires the use of a so-called coding or guide frame, in addition to the RAST 2.5 standard, detailed coding via bars between the contacts, side walls or interlocks with direct contacting of the circuit board have established themselves as customer-specific, non-standardized solutions.
Naturally, the number of different codings is limited. Especially in applications with numerous small-pole connectors, it was hardly possible to find enough hidden codes to exclude errors in the device assembly. There are now solutions with double-row coding. There is a row of coding lugs on the housing at the top and bottom.
Cable connection technologies
RAST connectors with insulation displacement, crimp and screw terminal technology are common. The insulation displacement technology (IDC) has by far the largest market share due to its economical wiring. While crimp contacts are always attached individually, fully automatic machines pull in up to 8 lines at the same time when producing cable sets with connectors using insulation displacement technology (IDT). These systems not only accelerate the production process for wire harnesses, but also enable them to be tested in an integrated manner at the same time, thus reducing costs in the production process as well as quality testing costs. This can significantly reduce errors in cable harnesses.
Service areas
Designed for two power ranges - RAST 2.5 for signal currents, RAST 5 for power currents - the RAST plug-in connections are available in a large number of versions, with different fits, codings and locking options. Very precise RAST 2.5 and RAST 5 specifications virtually “standardize” a number of connection properties, e. B. the geometric dimensions of the housing, all function-relevant dimensions and connector features such as the inner or outer locking. Furthermore, a service life test is required, the so-called 4,000-hour test, which is tailored to a device service life of 15 years in the household. In order to rule out errors due to incorrect attachment later in the device assembly, cable outlet directions and above all the basic coding are specified.