Evaluation of flitch plate losses in power transformers

Abstract

Literature available on flitch plate loss analysis is quite scarce. Calculation of losses and temperature rises occurring in structural parts of a transfanner is a very complex task due to magnetic and thermal non-linearity. Karsai et. al. have given an approximate but practical method of calculation of losses and temperature rise of critical strwtural parts of a transformer [2]. Eddy-current losses arising in metallic parts of rectangular cross section are calculated by an analytical method which makes certain approximations based on experimental factors [3]. Field strength at the inner edge of the LV winding is assumed to vary periodically with a sinusoidal distribution in the space along the height of the winding, and the non-sinusoidal nature is accounted by multiplying loss by a factor. The approximations made are: eddy current reaction is neglected and only amplitude of harmonic campanents of the field strength in the z direction (perpendicular to plate surface) are subject to change, their wavelengths and phase positions remaining unaltered. For a l l l y slotted flitch plate, the

Fast computation of hot spots temperature due to high current cable leads in power transformers tank walls

“…To simulate convection between transformer oil and tank wall (inside the transformer) a top oil temperature T top _ oil = 72.3 °C and a convective heat transfer coefficient h oil‐tank = 138 W / m 2 K are determined and set to the internal face of tank wall using the theory showed from .…”

Loss reduction by combining electrical steels in the core of power transformers

“…A maximum top oil temperature of 80 °C was measured for the overexcited condition for the transformer core made of M‐6 steel, while for nominal excitation a maximum top oil temperature of 70 °C was measured for the same transformer with its core made of M‐6 steel. Furthermore, the procedure discussed in was applied to calculate the convection coefficients h c between the transformer oil and core. The properties of the oil as well as its top temperatures were used to estimate the convection coefficients between the oil and the core of the transformer for overexcited and nominal conditions.…”

Life‐cycle loss evaluation of power transformers serving large photovoltaic plants in vertically integrated and decentralised systems

“…The net effect of such a motivation would be firstly to defer any utility rate growths and secondly to achieve significant CO 2 emissions reduction through energy conservation. A few options [3–8] to improve the efficiency of transformer designs are: (a) to use a core material that is more efficient, (b) to reduce eddy current losses by using thinner laminations, (c) to ensure that air gap losses at the core joints (yoke and limbs) are minimised, (d) avoiding the use of core bolts and (e) winding materials may be more conductive or thicker.…”