The outcome of many power system studies is the specification of the required reactance of a new transformer to satisfy power system requirements such as voltage drop and ensuring that the prospective short circuit current does not exceed circuit breaker ratings. In this note the factors which determine the reactance of a transformer and the challenges faced by the transformer designed when trying to achieve a particular reactance value are discussed.
For modelling purposes the double exponential function has great versatility in generating a remarkable range of different waveshapes. In this note we investigate eight different types of waveforms which can be generated using this function simply by changing the value of three complex numbers.
The satisfactory operation of power transformers connected on both sides in parallel requires careful consideration of a number of factors including: the polarity of connections, the phase sequence (for two three-phase units), phase displacements (i.e. the vector group for three-phase transformers), transformer voltage ratios, and the individual transformer per unit impedances. The interactions between these different parameters are discussed in this technical note.
In engineering schools, basic ac circuit analysis is one of the early concepts introduced to students. Later the propagation of surges during transients is discussed as an advanced topic. This hides the true nature of energy transfer in electric circuits which hidden by the limitations of steady state ac circuit analysis. In this note the true energy transfer mechanism in all electric circuits is discussed.