DETERMINATION OF THE TIME-TO-SATURATION OF CURRENT TRANSFORMERS IN SHORT-CIRCUIT TRANSIENT REGIMES

摘要

The existing methods of calculating the time-to-saturation of CT are analyzed. Since cases of core saturation have been observed in class P CT with high primary current multiples for which incorrect actions of the relay protection devices occurred in short-circuit transient regimes, in the proposed standard GOST R "Measuring transformers: Part 2. Requirements of current transformers" the coefficient of the transient regime and the time-to-saturation of CT are introduced as characteristics of CT. A method developed by the present authors is proposed for calculating the indicated time. Conclusions are drawn about the applicability of the methods in practical calculations. The calculation of the time-to-saturation of CT installed in 500 kV outdoor switchgear in a large electric power plant is presented as an example.