Method for checking electric contacts of an enclosed-type switching device and an auxiliary apparatus for use with the switching device to use the method

摘要

In an enclosed-type switching device having at least a pair of electric contacts, a method for checking the contacts without visual inspection wherein with the contacts closed, the resistance value between outer terminals connected to the contacts is measured and compared with a reference resistance value, so that the result of comparison is used to determine the degree of damage of the contacts. Also disclosed is an auxiliary apparatus for use with an enclosed-type switching device to facilitate application of the above-mentioned method, especially when the switching device is equipped with a plurality of parallel-connected sequentially closed or opened contact pairs. The auxiliary apparatus is arranged to interrupt the sequential operation of the contact pairs so that the resistance is measured during the interruption of the operation.