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

authored by

D. A.K. Pham, T. M.T. Pham, H. Borsi, Ernst Gockenbach

Abstract

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.

Organisation(s)

High Voltage Engineering and Asset Management Section (Schering Institute)

Type

Article

Journal

IEEE Transactions on Dielectrics and Electrical Insulation

Volume

20

Pages

2026-2034

No. of pages

9

ISSN

1070-9878

Publication date

12.2013

Publication status

Published

Peer reviewed

Yes

ASJC Scopus subject areas

Electrical and Electronic Engineering

Electronic version(s)

https://doi.org/10.1109/TDEI.2013.6678850 (Access: Unknown)