New Developments in Cathodic Protection Rectifiers

A review is made of recent developments in cathodic protection rectifiers. The most significant of these changes is the development of high voltage selenium and silicon rectifying elements and the use of these elements in circuits which are new to cathodic protection. This results in rectifiers which are more efficient, less costly, lighter, smaller, and lower in maintenance cost. Other changes in rectifier materials and designs have made possible improved cases, meter switches, transformers, circuit breakers, and other rectifier protective devices. Variations in rectifier types such as small oil immersed units have resulted in better distribution factors and less interference by means of distributed ground bed systems. Rectifiers with multiple outputs have been used in some applications with good results at a lower cost. Control of rectifier output has made many advances and will make many more in the near future. Present controls such as link bars and tap switches have been supplemented by constant current and special automatic current control rectifiers. Maintenance and inspection of the rectifiers has been greatly reduced and will be reduced even more in the future. Two controls of the future toward which much progress has been made are silicon power transistors and rectifiers which are controlled to a reference potential. 5.2.3