ANSI C84.1-2020: Electric Power Systems Voltage Ratings (60 Hz)

Red thunderstorm crashing in the clouds to represent overvoltages from not rating to ANSI C84.1-2020.

It’s not too difficult to find out what voltage ratings our equipment or systems need. However, it is important to consider, as overvoltages or voltage transients occur can impact the operating performance of equipment. Overvoltages are caused by two factors, internal and external. Internal factors include switching or temporary overvoltage, while the most common external factor is lightning. With the high likelihood of degradation or damage to equipment from events like voltage rise or overvoltages, it is imperative that electric supply systems are designed and operated to limit voltages through ANSI C84.1-2020.

The ANSI C84.1-2020 Standard

ANSI C84.1-2020 provides a better understanding of voltages associated with power systems and utilization equipment by establishing nominal voltage ratings and operating tolerances for 60 Hz electric power systems above 100 volts. This standard also includes voltage ratings up to and including 1200 kV maximum system voltage.

ANSI C84.1-2020 promotes many other benefits such as multiple standardizations including nominal system voltages and ranges of voltage variations, a guide for future development of equipment, and more. Overall, this standard helps to obtain a practical and economical operation.

Changes to ANSI C84.1-2020

Revising the 2016 edition of the same standard for voltage ratings, the newest version of ANSI C84.1-2020 includes:

  • An added informative Annex D gives guidance for all forms of distributed generation and storage that may cause voltage rise in conductors dedicated to the generation equipment as well as voltage rise to general supply systems.

Note from NEMA: The ASC 84 committee carefully considered raising allowable voltages at the point of common coupling to accommodate higher voltages that might be caused by the distributed generation. Many compelling arguments were given for not changing voltage ranges at points of common coupling with other equipment.

ANSI C84.1-2020 Electric Power Systems And Equipment – Voltage Ratings (60 Hz) is available on the ANSI Webstore.

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