HD 348 S7:1998

High-voltage alternating-current circuit-breakers

Scope

Applies to a.c. circuit-breakers designed for indoor or outdoor installation and operation at frequencies up to and including 60 Hz on systems having voltages above 1 000 V. Applies only 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. Also applies to the operating devices of circuit-breakers and their auxiliary equipment. However, circuit-breakers with a closing mechanism for dependent manual operation are not covered since a rated short-circuit-making current cannot be specified, and dependent manual operation may be objectionable because of safety considerations. Does not cover circuit-breakers intended for use on motive power units of electrical traction equipment, or circuit-breakers for use with overhead lines which include series capacitors.