TABLE OF CONTENTS A detailed deduction of the mathematical procedure is not given within the context of this book, but only the final equations are quoted. For further reading, reference is made to [1], [13]. In general, equipment in power systems is represented by equivalent circuits, which are designed for the individual tasks of power system analysis. For the calculation of no-load current and the no-load reactive power of a transformer, the no-load equivalent circuit is sufficient. Regarding the calculation of short-circuits, voltage drops and load characteristic a different equivalent circuit is required. The individual components of the equivalent circuits are resistance, inductive and capacitive reactance (reactor and capacitor), voltage source and ideal transformer. Voltage and currents of the individual components and of the equivalent circuit are linked by Ohm's law.
[13]Balzer, G., Nelles, D., and Tuttas, C.: Short-circuit current calculation acc. VDE 0102 (Kurzschlu stromberechnung nach VDE 0102). VDE-technical reports, Vol. 77. VDE-Verlag, Berlin, Offenbach/Germany, 2001. ISBN 3-8007-2101-5.
When dealing with two- and three-phase a.c. systems, it should be noted that currents and voltages are generally not in phase. The phase position depends on the amount of inductance, capacitance and resistances of the impedance. The time course, e.g., of a current or voltage in accordance with
can in this case be shown as a line diagram as per Figure 2.1. In the case of sinusoidal variables, these can be shown in the complex numerical level by rotating pointers, which rotate in...
