A Versatile Fail-Safe Trip Circuit for Reactor Safety Systems

A transistorized trip circuit is described which employs a simple self-testing technique to achieve a high degree of fail-safeness with a minimum number of components. It operates with d-c input currents in the range from 10 to 100 microamperes and can control up to 100 watts of load power. The trip differential for a load change from full power to zero power is less than 0.1 microampere; and the temperature stability of the trip point is better than 0.02 a/°C. This trip circuit may be used with either relay or solid-state logic and power switching circuits.