The Parallel Type Inverter

The parallel type inverter is one of many forms which are undergoing development at the present time. It gives promise of becoming of considerable importance and therefore the principles of operation should be better and more widely known. The object of this paper is to make a qualitative analysis of the operation of this type under different conditions of loading, and to present the results largely in the form of complete sets of oscillograms for further study. Inverters of the types now being studied involve the use of hot-cathode mercury-vapor tubes called thyratrons. The characteristics of these tubes are given briefly and the data necessary for an understanding of their operation in these circuits are presented. The principle of operation of the inverter circuit is developed by means of simple diagrams and then the actual conditions throughout the circuit are studied by means of oscillograms showing the voltages and currents in all of the essential parts. It is shown that the method of operation may be considered in a different manner from that usually assumed in the development of the circuit, inasmuch as the capacitor can be thought of as performing the function of giving the correct phase relation between the input current and the induced transformer primary voltage, rather than providing a sudden reversal of potential on the anode of the tube being stopped. This reversal is provided by the induced primary voltage. The current conditions for the various steps of operation are shown by simple diagrams.