Bryansk, Bryansk, Russian Federation
Bryansk, Bryansk, Russian Federation
Work objective is finding rational technical and economic solutions for examining current transformers for techspecs compliance satisfying the requirements of reinstalled microprocessor type protective relays and automation devices manufactured by NP EKRA LLC, taking into account DC component. Research methods: analytical methods for calculating the time of remnant magnetization in the core of a current transformer. Research results and novelty: it is understood that the saturation time of current transformers of the basic and backup protections, according to the results of the analytical method, was more than 25 ms, and for current transformers of differential bus bar protection was more than 5 ms. The obtained saturation time values for all types of current transformers built into oil circuit-breaker bushings (HV line) of 110 kV and bus bar coupling connector (BCC) of 110 kV (main protection, backup protection, differential bus protection), both in the absence and in the presence of remanent induction magnetic in CT cores with three-phase and single-phase short circuits, satisfy completely technical requirements either of microprocessor type protective relays or CT differential bus bar protection. Conclusion: built into CT BCC circuit-breaker bushings of 110 kV and oil circuit-breaker bushings (HV line) of 110 kV Foundry substations do not necessitate a mandatory replacement in case of non-complex redesign of microprocessor type protective relays and automation devices. When replacing oil circuit breakers with gas-insulated ones, it is recommended to use CT with similar characteristics.
voltage transformer, DC component, microprocessor type protective ECA relays, saturation time
1. Riyas Ahamed, M. Saturation Analysis of Current Transformer, M. Riyas Ahamed, M. Vimalraj, S. Rao Arjuna. International Journal of Research & Review, vol.2, Issue: 6, 2015, pp. 337 - 342.
2. Seryakov, A.A. Current transformers in transient modes, A.A. Seryakov. Electrotechnical market, 2014, no. 3 (57), pp. 18 - 21
3. Kuzhekov, S.L. On the problem of choosing and replacing current transformers for protection relays, S.L. Kuzhekov, A.A. Degtyarev, N.A. Doni, A.A. Shurupov. Izv. vuzov, Electromechanika, 2020, vol. 63. no. 6, pp. 72 - 82. DOIhttps://doi.org/10.17213/0136-3360-2020-6-72-82.
4. GOST R5866-2019.United power system and isolated power systems. Relay protection. Inductive measuring current transformers for protection with a closed magnetic circuit. Methodology guidelines for determination of time to saturation during short circuits.
5. Guidelines for checking and selecting current transformers. Relay protection and automation cabinets series SHE2607, SHE2710. EKRA.650323.085 D.
6. CS 56947007-29.240.10.028-2009. The standards for technological design of substations (NTP PS) of alternating current of JSC FGC UES with the highest voltage of 35 - 750 kV.
7. El-Amin, I.M. Saturation of Current Transformers and its Impact on Digital Overcurrent Relays, I.M. El-Amin, N. H. Al-Abbas, 2006 IEEE/PES Transmission & Distribution Conference and Exposition: Latin America, 2006, pp. 1-6, doi:https://doi.org/10.1109/TDCLA.2006.311516.