[en] Purpose: To protect simply various control devices from a fire as disposed in a nuclear power plants. Constitution: The input unit and the output unit of an electronic control circuit are connected through an opto-electric converter circuit to an optical fiber glass. A power supply control circuit for supplying a current is connected to the above electronic control circuit to receive the external power through the control circuit. A secondary battery having a high capacity condenser is connected to the above power supply control circuit. In the control equipment of such a configuration, an optical fiber cable made of quartz glass is employed as a signal transmission line. Therefore, the equipment can endure the high temperature, and even if the power cable is burnt, the power is supplied from the secondary battery to secure a fire resistance. (Kamimura, M.)