Frequency response analysis — Low frequency characteristics and fault diagnosis on power transformers

2010 ◽  
Author(s):  
Hormatollah Firoozi ◽  
Nami Mahmoodi ◽  
Mohammad Kharezi ◽  
M. I. Ghiyasi
Keyword(s):  
Fault Diagnosis ◽  
Frequency Response ◽  
Low Frequency ◽  
Frequency Characteristics ◽  
Power Transformers ◽  
Response Analysis ◽  
Frequency Response Analysis

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.

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