This paper develops a novel dynamic correction method for the reliability assessment of large oil-immersed power transformers. First, with the transformer oil-paper insulation system (TOPIS) as the target of evaluation and the winding hot spot temperature (HST) as the core point, an HST-based static ageing failure model is built according to the Weibull distribution and Arrhenius reaction law, ...

An original electronic device for compensating ratio and phase-displacement errors, of measuring current transformers and clamp-on probes, is proposed. It is specially intended for low-frequency applications (power frequency and its harmonic components), where the magnetizing current is the main cause of measuring errors. This system reduces the magnetic flux in the transformer core, reducing i...

Lumped Parameter Model is well known in solving high frequency signal propagation in high voltage transformer windings. At Southampton University, the modelling technique has been improvised and employed to solve partial discharge (PD) problem occurred within deep inside transformer windings. Firstly, a lumped capacitive parameter model was considered and secondly a transmission line lumped par...

Inductive magnetic probes are often used to measure oscillating magnetic fields in plasma.r3 The sensitivity of a magnetic probe to electrostatic potentials (“capacitive pickup”) is usually an important consideration. Centertapped construction of such a probe, shown in Fig. 1 (b), helps to minimize capacitive pickup with respect to a simply wound probe [Fig. 1 (a)]. This relies on the fact that...

A method of modeling internal turn-to-earth and turn-toturn faults in distribution transformer is discussed in this paper. The models are entirely compatible with the Alternative Transients Program(ATP). The simulation of the faults is based on known leakage factors between the various coils of the transformer. These leakage factors are evaluated by using a simple method implemented in this pap...

The winding hot-spot temperature is one of the most critical parameters that affect the useful life of the power transformers. The winding hot-spot temperature can be calculated as function of the top-oil temperature that can estimated by using the ambient temperature and transformer loading measured data. This paper proposes the estimation of the top-oil temperature by using a method based on ...

Power transformers represent the largest portion of capital investment in transmission and distribution substations. In addition, power transformer outages have a considerable economic impact on the operation of an electrical network. One of the most important parameters’ governing a transformer’s life expectancy is the hot-spot temperature value. Due to under estimation of stray losses in powe...

Improvement of diagnostic methods for both power and distribution transformers is crucial considering the part they play in electrical networks as well as their cost. Transfer function based testing of transformers is one of the methods that has been introduced recently. This method enables the identification of winding deformations resulting from the short circuit currents and winding dislocat...

power transformers are key components in electrical power supplies and their failure could cause severe consequences on continuity of service and also generates substantial costs. identifying problems at an early stage, before catastrophic failure occurs, is a great benefit for reliable operation of power transformers. frequency response analysis (fra) is a new, well-known and powerful diagnost...