Simulations of Currents in Conditions of Electrical Damage in the Windings of a Single-Phase Furnace Transformer with a
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lations of Currents in Conditions of Electrical Damage in the Windings of a Single-Phase Furnace Transformer with a Split Secondary Winding A. N. Novozhilova, *, T. A. Novozhilovb, and D. M. Rakhimberdinovaa a
Toraighyrov Pavlodar State University, Pavlodar, 140008 Kazakhstan bOmsk State Technical University, Tomsk, 644050 Russia *e-mail: [email protected]
Received July 11, 2019; revised October 18, 2019; accepted November 21, 2019
Abstract—A mathematical model is suggested to simulate currents under conditions of electrical damage in the windings of a single-phase furnace transformer with a split secondary winding. A method to reduce the number of equations in this mathematical model with many splits has been developed, which allows one to use iterative methods, e.g., the Gauss method, to determine currents in the windings. The effectiveness of the obtained model has been experimentally verified. It has been shown that the error in modeling the currents in the windings of a single-phase furnace transformer with secondary winding splitting during a short circuit in the primary winding does not exceed 10–15%. On the basis of the method to reduce the number of equations in a mathematical model, mathematical models have been developed; they allow one to simulate the currents in the windings of a furnace transformer during the short circuit in a short network with the break in a splitting conductor and under the normal load mode. Keywords: mathematical model of a single-phase furnace transformer with a split secondary winding, electrical damage in windings, coil circuit, open circuit, and short circuit of a conductor DOI: 10.3103/S1068371220060073
A typical structural feature of a single-phase transformer for ore-thermal production is the presence of a split secondary winding. It is carried out in the form of g single-turn insulated windings made by a bus with large cross section; the most commonly used circuit is one in which the secondary winding of a transformer has from two to eight splits. If each splitting is connected with the load through a separate current lead, electrical damage in the form of a short circuit in the primary winding as well as an open or short circuit in one of the split current conductors can occur in the transformer–current conducting system. To protect transformers with a split secondary winding from electrical damage, current cutoff, maximum current protection, and gas protection are usually used; however, current protections are insensitive to coil circuit in the primary winding and insensitive to breakage and short circuit of the one of the splits, and gas protection has a long time of response, especially in winter, and also does not respond to electrical damages in the circuit of conductors. The differential transverse protection on magnetic current transformers is highly sensitive to these damages; however, to determine the parameters of this
protection, it is necessary to simulate the currents in the transformer windings with coil circuit in the primary winding and e
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