Charles F. Hill

A New High-Voltage Insulation for Turbine-Generator Stator Windings

This paper reports the development of a new synthetic resin bonded mica tape insulation for high-voltage stator windings. It reviews the problems associated with earlier forms of high-voltage machine insulation. The general construction and processing of the insulation are described briefly. Comprehensive test data are presented on the characteristics of the materials employed and the resultant physical and electrical properties obtained on the composite insulation. This new insulation is now being applied to turbine generators for central station service.

Temperature limits set by oil and cellulose insulation

The life of cellulose insulation in oil has been investigated as a function of temperature under conditions of free access to oxygen and also in an inert atmosphere. Temperatures up to 140 degrees centigrade have been used. An attempt has been made also to study the life of oils as a function of oxygen concentration in an actual transformer at various temperatures. The amount of oxygen to produce a given acidity was also determined. On the basis of these data on oils, an attempt has been made to calculate rates of oxygen absorption by oil which may be used to estimate the relative deterioration in transformers of other dimensions. The results show cellulose deteriorates only mechanically, retaining its electrical properties. It is subject to both temperature and oxidation effects, the temperature effect, of course, taking place above 105 degrees centigrade.

Improvements in Insulation for High-Voltage A-C. Generators

A discussion is given of the insulation problem in relation to increased size, rating, and voltages of turbo alternators and some results of experimental studies given showing the possibilities of improving the insulation to take care of such increases. Mention is made of the effects of high voltage testing and the use of hydrogen on the insulation problem and finally an explanation of a device for the elimination of corona formed around armature coils.

Abridgment of improvements in insulation for high-voltage A-C. generators

A discussion is given of the insulation problem in relation to increased size, rating, and voltages of turbo alternators, and some results of experimental studies are given showing the possibilities of improving the insulation to take care of such increases. Mention is made of the effects of high-voltage testing and the use of hydrogen on the insulation problem, and finally, an explanation of a device for the elimination of corona formed around armature coils.