Hot Cathode Tubular Fluorescent Lamp Circuit Analysis

It occurred to the author, some time ago, that a study of the fluorescent lamp circuit, coupled with a description of some practical tests, would be useful to people dealing with this new form of lighting. It had been apparent, and was forcibly brought out when work on the paper was proceeding, that a knowledge of A.C. theory was essential if one is to be able to understand thoroughly the fluorescent lamp circuit. But once having grasped such A.C. theory, leading to the better understanding of the circuit, it follows that the reasons for the inclusion of the component parts of the circuit such as choke and capacitor, etc., are made plainer.

The paper therefore describes the circuit and the lamp, as an introduction, and this information has largely been obtained from the various technical articles which have been published from time to time. The tests described are such as can be undertaken by anyone with the necessary instruments. The vector diagrams have been constructed from the results of the tests, and it has been assumed that the alternating quantities were sinusoidal. Although this assumption is not strictly correct it was considered that approximate vector diagrams so constructed would serve to illustrate the results satisfactorily. The conclusions drawn, it is hoped, will help lighting and installation engineers and others to a better understanding of this new type of lighting and the criticisms offered will, it is hoped, be taken in the right spirit.