Network faults impact on operation of NOM-10 voltage transformers

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Authors:

A.A. Malinovskyi, Dr. Sci. (Tech.), Professor, National University “Lviv Polytechnic”, Head of the Department of Electrical Power Supply of Industrial Enterprises of Cities and Agriculture, Lviv, Ukraine

Ye.Yu. Hushchyn, National University “Lviv Polytechnic”, postgraduate student, Lviv, Ukraine

Abstract:

PurposeTo study electromagnetic processes in NOM-10 transformer during network faults using its mathematical model.

Methodology. The mathematical model of the NOM-10 transformer with an additional middle HV winding terminal, allowing to investigate the processes inside the transformer during internal network overvoltage, taking into account the influence of aperiodic component of different frequency. The model of network allows changing the frequency of the internal overvoltage aperiodic component, damping rate fluctuations and the time of occurrence of ground fault.

Findings. Investigations of transient electromagnetic processes in the NOM-10 transformer with triggered HV fuse have been done for the case of ground fault in the network. We have specified the frequency ranges of the aperiodic component leading to a dangerous surge on the transformers insulation, and maximum surge levels.

Originality. The possible values of overvoltage on NOM-10 transformers isolation in case of triggering of HV fuse and maximum values of network overvoltage have been defined. We have shown that dangerous overvoltage on NOM-10 isolation can be caused by ferroresonance processes that occur at frequencies above 50 Hz.

Practical value. We have improved the reliability of equipment with HV windings through measures of the internal resonance prevention.

References:

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4. Malinovskyi, A.A., Buchkovskyi, I.R., Nykonets, O.L., Hushchyn, Ye.Yu. (2012), “Experimental research of electromagnetic processes in windings of NOM-10 voltage transformer under influence of free current component”, Visnyk Natsionalnoho Universytetu “Lvivska Politekhnika”, no. 736, pp. 88–93.

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 ГОСТ 2213-79. Предохранители переменного тока на напряжение 3кВ и выше. Общие технические условия.

 

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ISSN (print) 2071-2227,
ISSN (online) 2223-2362.
Journal was registered by Ministry of Justice of Ukraine.
Registration number КВ No.17742-6592PR dated April 27, 2011.

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