Transient-state analysis of MV instrument transformers

• Published in: Electric power systems research Vol. 168; pp. 162 - 168
• Main Authors: Lamedica, R., Pompili, M., Sangiovanni, S., Calcara, L., Ruvio, A., Cauzillo, B.A.
• Format: Journal Article
• Language: English
• Published: Amsterdam Elsevier B.V 01.03.2019; Elsevier Science Ltd
• Subjects: Coils (windings); Control systems; Controllers; Electric potential; Electricity distribution; Electricity generation; Fast transient; Inductive voltage transformers; Instrument transformers; Laboratory tests; Measurements; Shielding; Theoretical model; Transformers; Voltage transformers; Fast transient; Theoretical model; Measurements; Inductive voltage transformers
• ISSN: 0378-7796; 1873-2046
• DOI: 10.1016/j.epsr.2018.11.015

•Analysis of MV instrument transformers in transient-state.•Overvoltages transferred from primary windings to the secondary ones when a fast voltage impulse excites machines.•Comparison of the results obtained through experimental tests and a theoretical study. This study illustrates how selected instrument voltage transformers (VTs-I) behave in a transitory state. Some laboratory tests are conducted on medium voltage (MV) inductive voltage types to evaluate the voltage transferred from primary to secondary windings when a fast voltage impulse (1.2/50μs) excites three machines constructively in different ways. Possible effects of metal parts present in the laboratory on the VTs-I behavior are analyzed, and other tests are conducted to determine a suitable shielding for the VTs-I. In order to interpret the experimental results, a theoretical study is performed using a simplified model of the instrument transformer. Finally, characteristic parameters are assigned values that were derived from experimental tests.