This standard is also applicable to the operating devices of circuit-breakers and to their auxiliary equipment. 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. IEC62271-100 only applicable to three-pole circuit-breakers for use in three-phase systems and single-pole circuit-breakers for use in single-phase systems. Note: Although primarily dedicated to three-phase systems, this standard can also be applied to single-phase or two-phase systems. 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. This part of IEC 62271 specifies circuit-breakers designed for indoor or outdoor installation and for operation at frequencies of 50 Hz and 60 Hz on systems having voltages above 1 000 V. This standard most used for medium voltage and high voltage circuit breakers. This standard is part 100 from IEC 62271 that published about switchgears. Standards are an important source for understanding, testing, and educating a variety of switchgear. IEC Standards play a very important role in familiarizing and testing different switchgears. The IEC also manages four] global conformity assessment systems that certify whether equipment, system, or components conform to its international standards. IEC standards cover a vast range of technologies from power generation, transmission, and distribution to home appliances and office equipment, semiconductors, fiber optics, batteries, solar energy, nanotechnology, and marine energy as well as many others. The International Electrotechnical Commission (IEC) is an international standards organization that prepares and publishes international standards for all electrical, electronic and related technologies – collectively known as “electrotechnology”. Photo from IEC 62271-200 standard General about IEC: