CIGRE Study Committee A3 facilitates and promotes the progress of engineering and the international exchange of information and knowledge in the field of high voltage equipment. Its goal is to add value to this information and knowledge by means of synthesizing state-of-the-art practices and developing recommendations.Hiroki Ito joined Mitsubishi Electric Corporation in 1984, where he had engaged in the research and development of high voltage DC and AC gas circuit breakers. From 1989 to 1991, he worked in the Coordinated Science Laboratory at the University of Illinois. In 1994, he received his Ph.D. from the Tokyo Institute of Technology, Japan. He was the technical director of Mitsubishi Electric High Voltage and High Power Testing Laboratories from 2005 to 2012. He is currently the Senior Chief Engineer of Energy and Industrial System Center, Mitsubishi Electric. In CIGRE, hewas the convener of CIGRE WG A3.22 and 28 that investigated the specifications of UHV substation equipment. He is also a member of IEC 62271-310 MT40: Electrical endurance tests of circuit breakers, and IEC 62271-302: Controlled switching. From 2012 to 2018, he has been the Chairman of CIGRE Study Committee A3: High voltage equipment.

• Chapter 1: Study Committee A3 activity.- Chapter 2: Switching Equipment in Power systems.- Chapter 3: Interrupting phenomena.- Chapter 4: Switching Phenomena in Power systems.- Chapter 5: Circuit Breakers (Oil breaker, Air-blast breaker, Gas circuit breaker, VCB, GMCB).- Chapter 6: AC Disconnecting switches and Earthing switches.- Chapter 7: Fault Current Limiters.- Chapter 8: Controlled switching.- Chapter 9: HVDC switching equipment.- Chapter 10: Novel technologies.

CIGRE Study Committee A3 facilitates and promotes the progress of engineering and the international exchange of information and knowledge in the field of high voltage equipment. Its goal is to add value to this information and knowledge by means of synthesizing state-of-the-art practices and developing recommendations.Hiroki Ito joined Mitsubishi Electric Corporation in 1984, where he had engaged in the research and development of high voltage DC and AC gas circuit breakers. From 1989 to 1991, he worked in the Coordinated Science Laboratory at the University of Illinois. In 1994, he received his Ph.D. from the Tokyo Institute of Technology, Japan. He was the technical director of Mitsubishi Electric High Voltage and High Power Testing Laboratories from 2005 to 2012. He is currently the Senior Chief Engineer of Energy and Industrial System Center, Mitsubishi Electric. In CIGRE, hewas the convener of CIGRE WG A3.22 and 28 that investigated the specifications of UHV substation equipment. He is also a member of IEC 62271-310 MT40: Electrical endurance tests of circuit breakers, and IEC 62271-302: Controlled switching. From 2012 to 2018, he has been the Chairman of CIGRE Study Committee A3: High voltage equipment.

• Chapter 1: Study Committee A3 activity.- Chapter 2: Switching Equipment in Power systems.- Chapter 3: Interrupting phenomena.- Chapter 4: Switching Phenomena in Power systems.- Chapter 5: Circuit Breakers (Oil breaker, Air-blast breaker, Gas circuit breaker, VCB, GMCB).- Chapter 6: AC Disconnecting switches and Earthing switches.- Chapter 7: Fault Current Limiters.- Chapter 8: Controlled switching.- Chapter 9: HVDC switching equipment.- Chapter 10: Novel technologies.