Voltage Standardization of A-C. Systems From the Viewpoint of the Electrical Manufacturer

In outlining the history of voltage standardization, it is observed that there has been separate standardization of voltages of various types of apparatus, rather than standardization of a complete operating system. The results of a questionnaire answered by 22 operating companies are analyzed and the conclusion is drawn that the use of the old standard transformer voltages involved, in many cases, over-exciting the transformers or generators in order to maintain satisfactory voltage at the consumers´ terminals. The reason is that the existing transformer voltage standards do not compensate for the line drop in transmission lines and feeders. The voltage standards of the International Electrotechnical Commission are set forth, indicating a partial agreement as to maximum system voltages with the proposed standards, although arrived at by a different method. The I. E. C. standardization, however, is not so complete as the proposed system. In describing the proposed standards, certain basic principles are laid down as the conditions which must be fulfilled. The proposed system of voltage standards starts with already standardized Utilization voltages at the low end of the scale and suggests tranformner voltage ratings and ratios which will allow proper voltage to be supplied to the consumers without over-exciting any of the transformers or generators in the system, and ties in the transformer and apparatus voltages with system voltages, based on the A. I. E. E. definition of rated circuit voltages. The proposed standards thus cover the whole field of voltages of a-c.