10176

# Phasor Representation for Three-Phase Power Transmission

Three-phase electric power is a method of alternating-current electric power transmission, which is in worldwide use in electric power distribution grids. The system was invented by Nikola Tesla in 1887–1888.
The three conducting wires are commonly colored black, red, and blue. The graphic shows the three correspondingly colored phasors representing voltage and current 120º apart, rotating at 50–60 Hz. Depending on whether the reactance of the load is inductive or capacitive, the voltage leads or lags the current, respectively. (You can refer to the handy mnemonic "ELI the ICEman".) The power factor is defined as the ratio , where is the active power (measured in watts), which depends on the resistance, and , the apparent power (measured in volt-amperes), which depends on the total impedance. The phase angle between the voltage and current phasors is then given by . The power factor is equal to 1 for a pure resistance, but decreases while the phase angle increases for larger reactance.

### DETAILS

The Demonstrations in Related Links by Harley H. Hartman show sinusoidal plots of three-phase currents. For more information on three-phase electric power, see http://en.wikipedia.org/wiki/Three-phase_electric _power.

### PERMANENT CITATION

Contributed by: William Unbehaun and S. M. Blinder
Relay Tech, Tacoma Power, and Wolfram Demonstrations Project
 Share: Embed Interactive Demonstration New! Just copy and paste this snippet of JavaScript code into your website or blog to put the live Demonstration on your site. More details » Download Demonstration as CDF » Download Author Code »(preview ») Files require Wolfram CDF Player or Mathematica.

#### Related Topics

 RELATED RESOURCES
 The #1 tool for creating Demonstrations and anything technical. Explore anything with the first computational knowledge engine. The web's most extensive mathematics resource. An app for every course—right in the palm of your hand. Read our views on math,science, and technology. The format that makes Demonstrations (and any information) easy to share and interact with. Programs & resources for educators, schools & students. Join the initiative for modernizing math education. Walk through homework problems one step at a time, with hints to help along the way. Unlimited random practice problems and answers with built-in Step-by-step solutions. Practice online or make a printable study sheet. Knowledge-based programming for everyone.