HD 348 S3:1989

High-voltage alternating-current circuit-breakers

Scope

This standard is applicable to a.c. circuit-breakers designed for indoor or outdoor installation and for operation at frequencies up to and including 60 Hz on systems having voltages above 1 000 V - 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 are subject to agreement between manufacturer and user - This standard is also applicable to the operating devices of circuit-breakers and to their auxiliary equipment - However, 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 may be objectionable because of safety considerations - This standard does not cover circuit-breakers intended for use on motive power units of electrical traction equipment, these are covered by IEC Publication 77, Rules of Electric Traction Equipment - Circuit-breakers for use with overhead lines which include series capacitors are not within the scope of this standard (Test to prove the performance under abnormal conditions should be subject to agreement between manufacturer and user - Such abnormal conditions are, for instance, cases where the voltage is higher than the rated voltage of the circuit-breaker, conditions which may occur due to sudden loss of load on long lines or cables - This standard is not necessarily applicable to circuit-breakers and the other on the other side