Analysis of the Findings of the Study of the Time to Saturation of Current Transformer Magnetic Circuits Located at Electric Power Facilities

Emergencies associated with incorrect operation of relay protection and automation (RPA) devices due to saturation of current transformers (CTs) can lead to great economic damage. The article presents an analysis of regulatory and technical documentation containing requirements for the quality of CT functioning in transient modes, statistical data on the results of calculations performed in accordance with the requirements of GOST R 58869–2019, as well as an analysis of the correctness of the assumptions introduced by it. To calculate the time to CTs saturation a special program was developed that automates the calculation methods, taking into account the assumptions focused on performing the manual calculations. The program takes into account the variation of the short circuit switching angle, the phase difference of the short circuit currents flowing through the branches feeding the short circuit point, the calculation of all CTs of a three-phase group with automatic selection of the worst result. The results obtained allow us to conclude about the relative number of CTs that do not meet the requirements of GOST R 58869–2019, the need to modernize existing methods and possible directions for such modernization. In addition, the article provides recommendations on the creation of automatic specialized software systems that can be used in the work of design, operating and research entities when they calculate the time to saturation of the CT magnetic circuits.