This part of IEC 60076-22 applies to protective devices mounted on liquid immersed power transformers according to IEC 60076-1 and reactors according to IEC 60076-6 with or without conservator for indoor or outdoor installation. It outlines the service conditions and the mechanical and electrical requirements that are common to all the devices, that are relevant for the safety of the machine having a function of signalization of abnormal operating conditions.