Abstract: A solid state protection system for AC electric motors driving high inertia loads requiring long acceleration times. An electroresponsive relay (OL) is separately responsive to permissible acceleration time, circuitry (DT, DC), acceleration overload current circuitry (ACA), and to normal running overload current circuitry (ACR). Up-to-speed detector and latch circuits (USD, USL) deactivate the acceleration time circuitry and overload current circuitry, and activate the running overload current circuitry upon attainment of normal running speed by the motor. The response levels of the overload and time response circuits are individually settable.

Abstract: A solid state motor control or power control universal assembly means and method whereby common parts are used to provide two basic semiconductor power pole versions, namely, a two-terminal power pole having two semiconductors in reverse-parallel connection between the terminals and a three-terminal power pole having two semiconductors in series connections between two terminals and a third terminal therebetween. These two power pole versions are the requiste subassemblies that may then be connected in various combinations to provide the numerous different types of motor control and power control systems commonly used.