EN 50216-3 applies to protective relays for hermetically liquid-immersed transformers, complying with the EN 60076/HD 398 series, and reactors, complying with EN 60289, without gaseous cushions for indoor and outdoor installation. This part of EN 50216 defines the: - operation limits; - outline and mounting details; - operational performance; - electrical characteristics; - dynamic characteristics. Should environmental conditions and dynamic stress requirements differ from those detailed in clause 3 of EN 50216-1, EN 50216-3 may then be applied by agreement between purchaser and supplier for those parts which are not affected by such abnormal installation conditions.