Motor-protective circuit-breakers PKZ have been manufactured by Moeller since 1932. Our ideas and developments have decisively influenced the trends in the protection of motors since then. The results are progressive concepts and marketable product innovations that again and again assume the role of international trendsetting, pioneering products. It was Moeller who pioneered the integration of overload protection and short-circuit protection into a compact device, thus abolishing the usual separation between both protective functions as used up to then. The awareness of this long tradition in the motor protection field has helped establish and maintain a core competence which has remained intact through to today. The term PKZ is not just the embodiment of quality, but also the generally used synonym by experts for motor-protective circuitbreakers.