Current-Limiting Reactor Characteristics

To prevent in large generating and distribution systems the possible concentration of enormous amounts of electrical energies at certain critical points, makes the extensive use of the current-limiting reactor a necessity. Connected reactor installations of 30,000 to 50,000-kv-a. capacities are not unusual any more. Aside from the many important issues involved in the generating system as a whole by the reactor equipment, the reactor itself became a very important factor. After the paramount issue of short-circuit protection is disposed of, a number of minor features is to be considered in the reactor design. The general characteristics of the various winding types, the circuit connections affecting the true reactance values, current distributions, throughout a multilayer reactor and conductor efficiencies are considered. Creeping due to heating of the conductor is evaluated. Attention is called to the fact, that the attraction or repulsion of the turns or layers within a reactor depends upon the layer or turn interconnections. The mechanical forces upon the conductor during short-circuit stresses are investigated and an approximate expression is given for their calculation.