Microswitches MK series 2006Microswitches MK series Introduction Microswitches of MK series have been developed in order to add new features to traditional and tested microswitches of Pizzato Elettrica (cross-reference at page 13). These new products have been designed with shapes and fixing perfectly interchangeable with the previous ones and with various additional functions useful to extend the applicatory field. The main innovation of this series is the tripping device evolved and modern, with qualitative features higher than solutions present on the market. The electrical contact on new microswitch has been realized with higher reliability technology, thanks to the double and redundant shape, and has the possibility to carry out operations with positive opening. The housing of the new microswitch provides the possibility to seat gaskets in order to seal the device against fine dusts or liquids up to IP65 degree. Fastening terminals of conductors are more practical and allow the fixing of different diameter cables or the possibility to choice different bends of faston contacts. For high quantity its possible to supply the microswitch only with the contact NO or NC, in order to minimize purchase costs. Contact block reliability In the following table we refer to the typical microswitch contact structure ( type A) normally used in the industry, compared with the innovative solution that Pizzato Elettrica uses in new MK series microswitches: movable contact with single interruption and double contacts ( type B). As you can see from the table below, this last structure ( type B) offers half of the contact resistance ( R) than the simple mobile contact ( type A) and a lower probability of failure ( fe). In fact, defined x the probability of a commutation failure of a single interruption, it results that in the type A the failure probability fe=x, in the 2 -4 type B the probability fe= x . This means that if in a certain situation the failure probability x is equal, for instance, to 1 x 10 (1 failed interruption every 10.000), we will have: - in type A one failed commutation every 10.000 - in type B one failed commutation every 100.000.000 Contact Probability of Type Figure Description resistance R failure fe A NO Contacts COMMON with single R=Rc fe=x Common interruption NC microswitch B Contacts NO COMMON with single 2 Pizzato R=Rc/2 fe x interruption and microswitch NC double contacts MK series Extended temperature range On request, on new MK series are available the versions with extended temperature range. Differently from standard MK microswitches with temperature range from +85 C to -25 C, these special versions can be used in places where the ambient temperature changes from +85 C to -40 C. They can be installed inside cold stores, sterilizers or other equipment with very low ambient temperature. Special materials that have been used to realize these versions, maintain unchanged their features also in these conditions, widening the installation possibilities. Microswitches for safety applications All microswitches that have the symbol beside the code are with positive opening, therefore suitable for safety applications. These microswitches are provided with a rigid connection between push button and NC contacts, which are opened by force through a strong/sturdy internal safety lever. The positive opening has been realised in conformity with the standard IEC 947-5-1, enclosure K, therefore these microswitches are suitable for the installation for peoples safety lever protection. page Microswitches MK