In abnormal operation, the alternator may be subjected to transient conditions which cannot be explained from steady-state theory. These transients may occur from- (i) Switching (ii) Sudden changes of load, (iii) Sudden short circuit (either line-to-line or line-to-neutral or from a symmetrical short circuit). These short circuits may develop severe mechanical stresses on the armature coils and their end turns [...]
Resistance and reactance (and consequently impedance) may be expressed in percentage or ohmic terms. In the case of rotating machines and transformers, manufacturer values are always in percentage terms while tables for cables and overhead lines are always in ohmic terms. Calculations can be made using either but not a mixture. For short circuit calculations, generally the percentage values are [...]
On occurrence of a short circuit at any point in a system, the short circuit current is limited by the impedance of the system up to the point of fault. Thus referring to Fig. 4.8, if a fault occurs on the feeder at point F, then the short circuit current from the generating station will have a value limited by [...]
Digital computer may be defined as a device that can compute by arithmetic processes. The basic processes used are addition and subtraction. These processes are also used in successive approximation or interaction to obtain function values, integration, solution of algebraic equations and linear and nonlinear differential equations. The input data describing the system is specified using the names of power [...]
A current limiting reactor, also sometimes called a series reactor, is an inductive coil having a large inductive reactance in comparison to its resistance and is used for limiting short circuit currents during fault conditions. These are installed in feeders and ties, in generator leads, and between bus sections to reduce the magnitude of short circuit currents and the effect [...]