Abstract: A bridge circuit of the type whereby a plurality of individual switching elements such as thyristors are mounted in a frame between four contact rails. To minimize interaction between current flow in the elements and to cause the load current to be divided roughly evenly over the elements, the elements are physically mounted between the rails so that adjacent parallel mounted elements belong to different arms and do not carry current at the same time.

Abstract: An improved parallel-resonant circuit inverter of the type having a rectifier, a thyristor DC/AC converter connected thereto and operating at a controllable frequency, a parallel resonant circuit with an inductive load and a method of operation of such circuit whereby the converter voltage U is maintained at a constant operating value U.sub.B for a constant DC current I.sub.g = I.sub.go, in a first control range characterized by a low resonant-circuit damping, and control of the direct current I.sub.g for the purpose of maintaining the DC/AC voltage constant at its operating value U.sub.B, in the case of a constant thyristor extinction time t.sub.L = t.sub.LO, in a second control range characterized by a high damping, as well as by transition from the first to the second control range, if t.sub.L becomes equal to t.sub.LO in the case of increasing resonant-circuit damping, and transition from the second to the first control range, if I.sub.g become equal to I.sub.go in the case of decreasing damping.