How to Calculate 3-Phase Line-To-Ground Voltage

Three-phase equipment is commonplace in power distribution systems.
••• Jupiterimages/ Images

Three-phase systems are prevalent in many power distribution systems. This is because 3-phase systems have built in efficiencies for high power transmission systems. The word 3-phase means the system has three separate lines, spaced 120 degrees apart, where each line carries the identical voltage. This identical voltage is the line to ground voltage.

    Find the kilovolt-amperes or "KVA" rating associated with the three-phase power distribution system. This is a standard rating associated with power distribution systems. Refer to system specification and/or circuit diagram. As an example, assume it's 20 KVA

    Find the current rating, or "A", in units of amperes or amps. Refer to system specifications and/or circuit diagram. As an example, assume it's 30 amps.

    Calculate the line to ground voltage using the formula: V (line to ground) = (KVA x 1000)/(I x 1.73). Continuing with the example:

    V (line to ground) = (20 x 1000)/(30 x 1.73) = 20000/51.9 = 385.4 volts.


About the Author

Dwight Chestnut has been a freelance business researcher and article writer for over 18 years. He has published several business articles online and written several business ebooks. Chestnut holds a bachelor's degree in electrical engineering from the University of Mississippi (1980) and a Master of Business Administration from University of Phoenix (2004).

Photo Credits

  • Jupiterimages/ Images