Simple approximate methods are developed and described for calculating the extremely low-frequency magnetic-shielding effectiveness for single- and double-layer infinite planar shields. In addition, ...exact expressions are given and "nearly exact" expressions are derived. Each expression has been compared to the exact expression in order to determine the range of parameters over which it is valid. Each approximate expression can be calculated rapidly and has a simple physical interpretation that leads to physical insight into the shielding process.
Switching performances of hollow contact rivets Zunko, P.; Bizjak, M.
IEEE transactions on components, hybrids, and manufacturing technology,
04/1992, Letnik:
15, Številka:
2
Journal Article, Conference Proceeding
A possibility of reducing contact material requirements in relays by application of hollow contact rivets was investigated. In the existing type of relays, standard massive contacts were replaced by ...specially prepared hollow contacts, shaped in the form of shells made of thin plates of the contact material. The results of contact performances of hollow and massive contact rivets, applied in the same type of relays for tests were compared. Evaluation of bouncing, temperature rise on contacts, arc duration at break, switching capacity, and electric contact life were performed according to IEC standards. Good or even better performance of hollow contacts were obtained. After tests some microscopical examinations of contact surfaces indicate erosion characteristics at higher electrical loads.< >
PDF