scholarly journals Measurement -based electrical parameters of power transformers for Frequency Response Analysis interpretation - Part I: Core analysis

2017 ◽  
Vol 20 (K3) ◽  
pp. 5-10
Author(s):  
Khoi Dinh Anh Pham
Keyword(s):  
Frequency Response ◽  
Power Transformers ◽  
Response Analysis ◽  
Frequency Response Analysis ◽  
Frequency Range ◽  
Electrical Parameters ◽  
Efficient Tool ◽  
Frequency Dependent ◽  
New Approach ◽  
The Core

Although the standard Frequency Response Analysis (FRA) test has been approved as an efficient tool to diagnose mechanical failures in power transformers, the demand to interpret FRA traces in practical and physical way is still requested. That means physical electrical parameters of transformers should be determined reasonably based on real measurements and afterwards are applicable for the interpretation. For purpose of FRA interpretation in practical manner, electrical parameters of power transformers in a physical equivalent circuit should be determined. As a first step, the paper introduces a new approach in determining frequency dependent core impedances of a distribution transformer based on the combination of circuit analysis of a duality-based model, measurements of driving-point impedances and experimental formulas. From that, two important contributions can be drawn. Firstly, frequency dependent core impedances are ready as available components in the circuit for FRA interpretation in broad frequency range. Secondly, the core parameters could be useful indicators for detecting relevant failures in cases there is no more failure on transformer windings.

scholarly journals Measurement-based electrical parameters of power transformers for Frequency Response Analysis interpretation-Part II: Winding Part II: Winding analysis

2017 ◽  
Vol 20 (K3) ◽  
pp. 11-17
Author(s):  
Khoi Dinh Anh Pham
Keyword(s):  
Frequency Response ◽  
Diagnostic Testing ◽  
Power Transformers ◽  
Response Analysis ◽  
Frequency Response Analysis ◽  
Frequency Range ◽  
Electrical Parameters ◽  
Frequency Dependent ◽  
The Core ◽  
Zero Sequence

For a practical Frequency Response Analysis (FRA) interpretation applicable to power transformers, frequency dependent electrical parameters of the core and windings in broad frequency range should be identified through non-destructive measurements. Since the core parameters are determined in Part I, electrical parameters of windings (resistances, capacitances) and leakage paths surrounding windings (leakage/zero-sequence impedances) of a distribution transformer will be discussed in this paper. Due to the fact that most parameters associated with the windings currently can only be measured at or around power frequency through diagnostic testing methods, the practical parameter-based FRA interpretation is not possible. To deal with this problem, the paper proposes a new approach based on the combination of different measured driving-point impedances and relevant analysis of the duality-based equivalent circuit in determining frequency dependent parameters associated with transformer windings. Results show that the physical FRA interpretation can be reasonable obtained for the test transformer in low and medium frequency range.

scholarly journals A New Multi-Conductor Transmission Line Model of Transformer Winding for Frequency Response Analysis Considering the Frequency-Dependent Property of the Lamination Core

Energies ◽  
2018 ◽  
Vol 11 (4) ◽  
pp. 826 ◽  
Author(s):  
Song Wang ◽  
Ze Guo ◽  
Ting Zhu ◽  
Hanke Feng ◽  
Shuhong Wang
Keyword(s):  
Transmission Line ◽  
Frequency Response ◽  
Complex Permeability ◽  
Response Analysis ◽  
Iron Core ◽  
Frequency Response Analysis ◽  
Frequency Dependent ◽  
The Core ◽  
Transformer Winding ◽  
Dependent Property

Multi-conductor transmission line (MTL) model of power transformer winding for frequency response analysis (FRA) has been successfully applied for the purpose of studying the characteristics of winding deformations. Most of the time it is considered that, at a frequency above 10 kHz, the flux does not penetrate the core, and the iron core losses due to hysteresis and eddy current can be neglected accordingly. However, in fact, there is still a little flux residing in the core, and it has a significant influence on inductances and resistances of transformer winding even up to approximately 1 MHz. In this paper, by introducing the anisotropic complex permeability of the lamination core into calculating inductances and resistances of the MTL model, a new MTL model considering the frequency-dependent property of the lamination core for FRA is presented. In addition, the accuracy and effectiveness of the MTL model are validated by means of a comparison between measured and emulated FRA results in a wide frequency range from 10 Hz up to 10 MHz. This precise MTL model of the transformer winding provides us a more objective and positive condition for simulation research of winding deformation detection.

Low-frequency response characteristics of three Grass model 7 polygraphs

1985 ◽  
Vol 58 (3) ◽  
pp. 1026-1030
Author(s):  
D. D. Hickey ◽  
J. Zaharkin
Keyword(s):  
Frequency Response ◽  
Low Frequency ◽  
Response Analysis ◽  
Frequency Error ◽  
Frequency Response Analysis ◽  
Frequency Range ◽  
Response Characteristics ◽  
Deflection Amplitude ◽  
Human Respiration ◽  
Grass Model

A low-frequency response analysis of three Grass model 7 polygraphs was undertaken. Observed error was generally found to fall within the manufacturer's stated range of +5 to -10% of DC signal height over the frequency range of human respiration (0.1–3 Hz), but this was not the case for frequencies greater than 6 Hz under certain circumstances. The magnitude of error was seen to vary directly with frequency and indirectly with pen-deflection amplitude and paper speed. The pen-oscillograph apparatus was the predominant source of low-frequency error, and this is probably due to pen inertia and pen friction on the writing surface. Two schemes to reduce such error are presented.

Sign in / Sign up

Export Citation Format

Share Document