Silicon carbide non-ohmic resistors

Resistors which pass a current proportional to the fourth or fifth power of the applied voltage are now widely used in many fields of electrical engineering. The first part of the paper discusses the behaviour of these resistors in terms of the characteristics of single contacts between silicon-carbide crystals. In the second part, the construction and properties of the resistors are described, and some typical examples are given of their uses for protection on transmission lines, in d.c. inductive circuits, in radio, for spark quenching at relay contacts, for voltage regulation, for field control of electrical machines and for various other purposes. The limitations which the properties of the material impose upon its field of usefulness are also indicated. The third part of the paper deals with the determination of the power that such a resistor can safely handle, which depends on the circuit in which it is used as well as on the means by which it is cooled. The Appendix discusses the methods of calculating the currents and voltages in circuits containing components of this special kind.