Abstract
"Safety plug switch" is used for controlling hazardous energy in order to protect the machine maintenance personnel working at any place where they could be injured by the unexpected release of hazardous energy. In view of the above, this paper proposes that the relation of "withdrawing and possessing the safety plug for hostage control," "unlocking the movable guard for opening it" and "accessing to the working space" should be made unate in terms of system by applying the "principle of safety confirmation" to the safety plug switch installation. To realize such unite system, this paper formulates these interrelations, presents them in the form of interlock structure and shows an example of configuration that can meet the required functions.
