The International Electrotechnical Commission (IEC) standard 61869, also known as "Instrument transformers," is a widely adopted specification for instrument transformers used in electrical power systems. This standard provides a framework for the design, testing, and operation of instrument transformers, ensuring their accuracy, reliability, and safety.

: Addition of Annexes E, F, G, and I to address modern technical challenges. Https://Www.En-Standard.Eu

IEC 61869-1: General Requirements for Instrument Transformers