1.1 Scope
This standard is applicable to a.c. circuit-breakers designed for indoor or outdoor installation and for operation at 50 Hz frequency on systems having standard voltages from 6kV to 1000kV.
It is only applicable to three-pole circuit-breakers for use in three-phase systems and single-pole circuit-breakers for use in single-phase systems. Two-pole circuit-breakers for use in single-phase systems and application at frequencies lower than 50 Hz are subject to agreement between manufacturer and user.
This standard is also applicable to the operating mechanism of circuit-breakers and to their auxiliary equipment. A circuit-breaker with a closing mechanism for dependent manual operation is not covered by this standard, as a rated short-circuit making-current cannot be specified, and such dependent manual operation is objectionable because of safety considerations.
This standard does not cover circuit-breakers intended for use on mobile power stations for electric traction equipment; these are covered by IEC 60077 [4] .
Generator circuit-breakers installed between generator and step-up transformer are not within the scope of this standard.
Switching of inductive loads is covered by IEC 62271-301.
Circuit-breakers with an intentional non-simultaneity between the poles, with the exception of circuit-breakers providing single-pole auto-reclosing, are not within the scope of this standard.
This standard does not cover self-tripping circuit-breakers with mechanical tripping devices or devices which cannot be made inoperative.
By-pass circuit-breakers installed in parallel with line series capacitors and their protective equipment are not within the scope of this standard; these are covered by IEC 60143-2 [6].
