Mathematical simulation of thermal state of digital current and voltage transformer in unfavourable weather conditionsElena E. Gotovkina, Grigory I. Parfenov, Nikolay N. Smirnov, Vladimir D. Lebedev and Vladimir V. TyutikovMATEC Web Conf., 194 (2018) 01021DOI: https://doi.org/10.1051/matecconf/201819401021