Electronic trip unit with a rating plug for circuit breakers, which has a switchable motor and line protection function

A circuit breaker (10) is rendered more versatile by providing an electronic trip unit (34) having more than one algorithm embedded in the software thereof to function as either a line protector or a motor protector. The rating plugs (40) of the invention may either be switchable between line and motor protection or the rating plugs may simply include a particular jumper thus enabling the circuit breaker to be converted from line to motor or motor to line based upon the rating plug selected. Whether the rating plug is switchable or the non-switchable jumper-type rating plugs of the invention are being employed the electronic trip unit and current transformer need not be changed in order to change the function of the circuit breaker between line protection and motor protection.