TABLE OF CONTENTS An understanding of system voltage nomenclature and preferred voltage ratings of distribution apparatus and utilization equipment is essential to ensure the proper design and operation of a power distribution system. The dynamic characteristics of the system should be recognized and the proper principles of voltage regulation applied so that satisfactory voltages will be supplied to utilization equipment under all normal conditions of operation.
Low voltage: A class of nominal system voltages 1,000 V or less
Medium voltage: A class of nominal system voltages greater than 1,000 V but less than 100,000 V
High voltage: A class of nominal system voltages equal to or greater than 100,000 V and equal to or less than 230,000 V
These voltages and their associated tolerance limits are listed in ANSI C84.1-1989 for voltages from 120 to 230,000 V, and ANSI C92.2-1987, Power Systems-Alternating Current Electrical Systems and Equipment Operating at Voltages Above 230 kV Nominal-Preferred Voltage Ratings. The nominal system voltages and their associated tolerance limits and notes in the two standards have been combined in Table 3.46 to provide a single table, listing all the nominal system voltages and their associated tolerance limits for the United States. Preferred nominal system voltages and voltage ranges are shown in boldface type, whereas other systems in substantial use that are recognized as standard voltages are shown in medium type. Other voltages may be encountered...
