On the development of transfer function method for fault identification in large power transformers on load

Nondestructive Fault Diagnosis of a Transformer Using Transfer Function Method

“…Among them, DGA is the most popular and reliable method. To overcome the drawbacks of DGA, the frequency response analysis (FRA) or the transfer function method (TFM) was suggested and is gradually recognized to be an excellent diagnostic tool [1]- [3]. Researches on the application of TFM to on-line monitoring are in progress as well.…”

Understanding the moisture temperature and ageing dependency of power transformer winding clamping pressure

“…In [49], based on results of a field investigation it has been concluded that conventional interpretation methods of FRA results leave uncertainties in identifying movements in the windings and loose clamping conditions. Thus explaining the contradicting conclusions of [10] and [11].…”

“…According to the findings of [10], loose clamping condition does not affect the resonance and anti-resonance frequencies but reduces the magnitude of minimum and maximum peaks in the mid and highfrequency ranges. However, in [11], authors have observed a shift in resonance and antiresonance frequencies in the FRA curve with changing winding clamping pressure. In [49], based on results of a field investigation it has been concluded that conventional interpretation methods of FRA results leave uncertainties in identifying movements in the windings and loose clamping conditions.…”

“…According to existing literature, frequency response analysis (FRA) and vibro-acoustic condition monitoring are potential techniques to detect variations in winding clamping pressure [10][11][12][13][14][15]. However, information on the exact behaviour of winding clamping pressure under dynamic operating conditions of an energised power transformer, which requires the use of the above techniques on a substation transformer, is scarce.…”

“…Among existing literature, [10] and [11] have investigated the possibility of using FRA technique to detect the loose clamping conditions of a transformer winding. According to the findings of [10], loose clamping condition does not affect the resonance and anti-resonance frequencies but reduces the magnitude of minimum and maximum peaks in the mid and highfrequency ranges.…”