This part of IEC 62271 is applicable to a.c. contactors and/or contactor-based controllers and
motor-starters designed for indoor installation and operation at frequencies up to and
including 60 Hz on systems having voltages above 1 000 V but not exceeding 24 000 V.
It is applicable only to three-pole devices for use in three-phase systems, and single-pole
devices for use in single-phase systems. Two-pole contactors and starters for use in singlephase
systems are subject to agreement between manufacturer and user.
Contactors and/or starters dealt with in this standard typically do not have adequate
short-circuit interruption capability. In this context, this standard gives requirements for
– motor starters associated with separate short-circuit protective devices;
– controllers - contactors combined with short-circuit protective devices (SCPD).
Contactors intended for closing and opening electric circuits and, if combined with suitable
relays, for protecting these circuits against operating overloads are covered in this standard.
This standard is also applicable to the operating devices of contactors and to their auxiliary
equipment.
Motor-starters intended to start and accelerate motors to normal speed, to ensure continuous
operation of motors, to switch off the supply from the motor and to provide means for the
protection of motors and associated circuits against operating overloads are dealt with.
Motor-starter types included are
– direct-on-line starters;
– reversing starters;
– two-direction starters;
– reduced kVA (voltage) starters;
· auto-transformer starters;
· rheostatic starters;
· reactor starters.
This standard does not apply to
– circuit-breaker-based motor-starters;
– single-pole operation of multi-pole contactors or starters;
– two-step auto-transformer starters designed for continuous operation in the starting
position;
– unbalanced rheostatic rotor starters, i.e. where the resistances do not have the same
value in all phases;
– equipment designed not only for starting, but also for adjustment of speed;
– liquid starters and those of the "liquid-vapour" type;
– semiconductor contactors and starters making use of semiconductor contactors in the
main circuit;
– rheostatic stator starters;
– contactors or starters designed for special applications.
This standard does not deal with components contained in contactors and contactor-based
motor-starters, for which individual specifications exist.