Three Phase Electricity



Click Here for E-Book Details



Click Here for E-Book Details

Three-phase voltage, frequency and number of wires

Although single-phase power is more prevalent today, three phase is still chosen as the power of choice for many different types of applications. Generators at power stations supply three-phase electricity. This is a way of supplying three times as much electricity along three wires as can be supplied through two, without having to increase the thickness of the wires. It is usually used in industry to drive motors and other devices.

three phase electricity is by its very nature a much smoother form of electricity than single-phase or two-phase power. It is this more consistent electrical power that allows machines to run more efficiently and last many years longer than their relative machines running on the other phases. Some applications are able to work with three-phase power in ways that would not work on single phase at all.

Three phase is a common method of electric power transmission. It is a type of polyphase system used to power motors and many other devices.

This article deals with where, how and why "three phase" is used. For information on the basic mathematics and principles of three phase see three-phase. For information on testing three phase equipment (kit) please see three-phase testing.

Three phase systems may or may not have a neutral wire. A neutral wire allows the three phase system to use a higher voltage while still supporting lower voltage single phase appliances. In high voltage distribution situations it is common not to have a neutral wire as the loads can simply be connected between phases (phase-phase connection).

Three phase has properties that make it very desirable in electric power systems. Firstly the phase currents tend to cancel one another (summing to zero in the case of a linear balanced load). This makes it possible to eliminate the neutral conductor on some lines. Secondly power transfer into a linear balanced load is constant, which helps to reduce generator and motor vibrations. Finally, three-phase systems can produce a magnetic field that rotates in a specified direction, which simplifies the design of electric motors. Three is the lowest phase order to exhibit all of these properties.

Most domestic loads are single phase. Generally three phase power either does not enter domestic houses at all, or where it does, it is split out at the main distribution board.

The three phases are typically indicated by colors which vary by country.


Return To Electricity Forum

Subscription

 
Training Courses

Low Voltage Arc Flash-Electrical Safety Training Workshop

  • September 9, 2014 - Mississauga, ON
  • September 11, 2014 - Winnipeg, MB
  • September 12, 2014 - Saskatoon, SK
  • September 15, 2014 - Edmonton, AB
  • September 17, 2014 - Richmond, BC

2-Day LV-HV Arc Flash Electrical Safety Workshop

  • September 9-10, 2014 - Mississauga, ON
  • September 15-16, 2014 - Edmonton, AB
  • September 17-18, 2014 - Richmond, BC

MV/HV Arc Flash/Electrical Safety Training Workshop

  • September 10, 2014 - Mississauga, ON
  • September 16, 2014 - Edmonton, AB
  • September 18, 2014 - Richmond, BC

Electrical Generators & Backup Emergency Power Systems

  • September 22-23, 2014 - St. Johns, NL
  • September 24-25, 2014 - Mississauga, ON
  • September 29-30, 2014 - Winnipeg, MB
  • October 1-2, 2014 - Edmonton, AB

Fire Alarm and Life Safety Systems

  • October 6-7, 2014 - Mississauga, ON
  • October 8-9, 2014 - Calgary, AB
  • October 14-15, 2014 - Richmond, BC
  • October 16-17, 2014 - Winnipeg, MB

Ontario Electrical Safety Code Training

  • October 9-10, 2014 - Mississauga, ON

Power System Design Engineering Course

  • October 14-15, 2014 - Mississauga, ON
  • October 16-17, 2014 - Edmonton, AB
  • October 20-21, 2014 - Richmond, BC

LV-MV Electrical Grounding for Industrial Power Systems

  • October 16-17, 2014 - Richmond, BC
  • October 20-21, 2014 - Edmonton, AB
  • October 27-28, 2014 - Mississauga, ON
  • November 3-4, 2014 - St. Johns, NL
  • November 17-18, 2014 - Saskatoon, SK
  • November 19-20, 2014 - Winnipeg, MB

Edmonton Electrical Grounding Week

  • October 20-24, 2014 - Edmonton, AB

High Voltage Electrical Grounding

  • October 22, 2014 - Edmonton, AB
  • October 29, 2014 - Mississauga, ON
  • November 5, 2014 - St. Johns, NL

Electrical Grounding For Oil & Gas Applications

  • October 23-24, 2014 - Edmonton, AB
  • November 6-7, 2014 - St. Johns, NL

Toronto Electrical Grounding Week

  • October 27-31, 2014 - Mississauga, ON

Edmonton Electric Motor Week

  • October 27-31, 2014 - Edmonton, AB

Industrial Electric Motor Management

  • October 27-28, 2014 - Edmonton, AB
  • November 17-18, 2014 - Mississauga, ON

VFD and Electric Motor Control Training

  • October 29-30, 2014 - Edmonton, AB
  • November 19-20, 2014 - Mississauga, ON

Telecommunications Electrical Grounding and Bonding

  • October 30-31, 2014 - Mississauga, ON

Industrial Electric Motor Testing

  • October 31, 2014 - Edmonton, AB
  • November 21, 2014 - Mississauga, ON

St. Johns Electrical Grounding Week

  • November 3-7, 2014 - St. Johns, NL

Power System Protection Engineering Course

  • November 13-14, 2014 - Mississauga, ON
  • November 17-18, 2014 - Richmond, BC
  • November 19-20, 2014 - Edmonton, AB

Toronto Electric Motor Week

  • November 17-21, 2014 - Mississauga, ON

Power System Modeling and Calculations Engineering Course

  • December 4-5, 2014 - Mississauga, ON
  • December 8-9, 2014 - Richmond, BC
  • December 10-11, 2014 - Edmonton, AB
 
Affiliates
 
Featured Product

Large Stocking Distributor Specializing in Instrument Transformers and Metering Components

Spectrum Industries, Inc.
Spectrum Industries is an Instrument Transformer electrical distributor and contract manufacturer located in Peabody, Massachusetts.
more...
 
Advertisement
 
Latest Buyer's Guide Companies
Sign Up Today and Receive Our FREE E- Newsletter

E-newsletter service - Exciting industry trends, technical developments, product information, forums and electrical training courses.