TY - JOUR

T1 - A new method for purposes of failure diagnostics and FRA interpretation applicable to power transformers

AU - Pham, D. A.K.

AU - Pham, T. M.T.

AU - Borsi, H.

AU - Gockenbach, Ernst

N1 - Copyright: Copyright 2016 Elsevier B.V., All rights reserved.

PY - 2013/12

Y1 - 2013/12

N2 - To diagnose electrical and mechanical failures on the active part of power transformers efficiently, different state-of-the-art testing methods are recommended to be performed since transformers are complex devices. Measurement results can be equivalent electrical parameters relating to the windings (resistances, leakage/zero-sequence inductances and capacitances), core magnetic property (via induced voltages and exciting currents) or terminal frequency responses (standard FRA tests). Consequently, it is not easy for normal users to implement all necessary measurements, which require much time and training skills due to use of different specialized testing devices. To help users for fast and efficient diagnostics, the paper presents a new method in determining most electrical parameters of the transformer active part based on only the drivingpoint impedance tests performed by means of a vector-network analyzer. More importantly, the method can be applied to give a FRA interpretation based on physical electrical parameters, which is currently requested from relevant standards. The physical FRA interpretation is found to be useful in calculating immeasurable series capacitances of windings in transformer bulk, which is still problematic until now. Investigation on a large distribution transformer shows that the new method is simple, less time consuming but efficient.

AB - To diagnose electrical and mechanical failures on the active part of power transformers efficiently, different state-of-the-art testing methods are recommended to be performed since transformers are complex devices. Measurement results can be equivalent electrical parameters relating to the windings (resistances, leakage/zero-sequence inductances and capacitances), core magnetic property (via induced voltages and exciting currents) or terminal frequency responses (standard FRA tests). Consequently, it is not easy for normal users to implement all necessary measurements, which require much time and training skills due to use of different specialized testing devices. To help users for fast and efficient diagnostics, the paper presents a new method in determining most electrical parameters of the transformer active part based on only the drivingpoint impedance tests performed by means of a vector-network analyzer. More importantly, the method can be applied to give a FRA interpretation based on physical electrical parameters, which is currently requested from relevant standards. The physical FRA interpretation is found to be useful in calculating immeasurable series capacitances of windings in transformer bulk, which is still problematic until now. Investigation on a large distribution transformer shows that the new method is simple, less time consuming but efficient.

KW - Driving-point impedance

KW - Failure diagnostics

KW - FRA

KW - Physical electrical parameters

KW - Power transformers

UR - http://www.scopus.com/inward/record.url?scp=84896299091&partnerID=8YFLogxK

U2 - 10.1109/TDEI.2013.6678850

DO - 10.1109/TDEI.2013.6678850

M3 - Article

AN - SCOPUS:84896299091

VL - 20

SP - 2026

EP - 2034

JO - IEEE Transactions on Dielectrics and Electrical Insulation

JF - IEEE Transactions on Dielectrics and Electrical Insulation

SN - 1070-9878

IS - 6

M1 - 6678850

ER -