Interchangeable solid state and thermal-magnetic trip units

A removable and replaceable multi-pole solid state trip unit assembly constructed to be positioned within a housing for a molded case multi-pole circuit breaker in place of a removable thermal-magnetic trip unit assembly;

• said solid state trip unit assembly including an insulating frame including a wall, main circuit conductor means for each pole of said assembly extending forward and behind said wall, individual first means for monitoring current flow in each of said conductor means, solid state circuitry for processing signals transmitted thereto by said first means and generating a tripping signal upon the occurrence of predetermined fault conditions;
• all of said first means and said solid state circuitry being positioned behind said wall;
• said conductor means having its front end adapted for connection to cooperating contact means within a circuit breaker housing wherein said solid state trip unit assembly is to be installed in place of a thermal-magnetic trip unit assembly;
• said conductor means having its rear end adapted for connection with elements external to such circuit breaker housing.