Reliable Switching of Small Contact Loads
The requirements for electromechanical relays have changed significantly in recent years. At the same time much relay-specific knowledge has been lost and is often not available in the electronic design community.While the maximum load limitations are well known, easier to determine and given in the relevant datasheets, the minimum load limits which can be applied are not known, difficult to determine and, due to liability reasons, values are given which do not represent the potential of electromechanical relays.An overview of the phenomena which have to be taken into consideration is given and the effect on the minimum permitted load which should be applied to contacts in relays.In order to design reliable electronic circuits with electromechanical relays, the load applied to the contacts, the requirements and limitations of the circuitry, the contact material, the environmental conditions and the protection of the relay housing must be known. A major factor affecting the reliability of relays in low level applications is the quality or cleanliness of the contact material used.When clean contacts are used, the minimum load is mainly defined by the voltageWhen these factors are known and properly taken into consideration, relays with gold contacts can be chosen for absolutely reliable operation at voltages a low as uV and currents as low as nA.Whenever silver contacts are used, the minimum voltage applied should be at least 5 V. Even more important for the use of silver contacts in low level applications is the design of the switching device. This must ensure that the contacts are efficiently protected and potential coatings on the contact surface are destroyed by relative movement during contact closing.
Relays Low level switching small load minimum contact load silver contacts gold contacts relays in electronic circuit
Werner Johler
Tyco Electronics Logistics Ag-Werk AXICOM Au Seestr.295, 8804 Au-Waedenswil, Switzerland
国际会议
温州
英文
45-53
2009-10-18（万方平台首次上网日期，不代表论文的发表时间）