THE 3 PHASE POWER
RESOURCE SITE

3 Phase Power Grain Dryer
3 phase power is used today for many applications ranging from the above grain dryer to saw mills, conveyer belt systems, refrigeration and air conditioning, etc.

3 Phase Contents
- 3 Phase Power Home
- 3 Phase Wiring
- 3 Phase Power Calculation
- 3 Phase Power Converter
- 3 Phase Converters
  * Rotary Phase Converters
  * Static Phase Converters
- 3 Phase Generators
- 3 Phase Transformers
  * 3 Phase Isolation Transformers
- 3 Phase Motors
- 3 Phase Electricity
- 3 Phase Power Loads
- 3 Phase Frequency
  * Frequency Converters
- 3 Phase Distribution
- 2 Phase Systems
- 1 Phase Loads on 3 Phase Power
- 3 Phase Loads on 1 Phase Power


3 phase power three phase power three phase electricity three phase generator 3 phase converter, rotary three phase

 

3 Phase Electricity

To Buy 3 Phase Converters
We Recommend ACE Brand.
Call 1-800-967-7217
Web Link:  3 Phase Converters

3 Phase Electrical Power

3-phase electricity is a common method of electric power transmission. It is a type of polyphase system.

This site details where, how and why "3 phase electricity" is used. For information on the basic mathematics and principles of 3 phase electricity see three-phase.

3 phase electricity has properties that make it very desirable in distribution. Firstly all three wires carry the same current. Secondly power transfer into a linear balanced load is constant.

Most domestic loads are single phase electricity. Generally 3 phase electricity either does not enter domestic houses at all, or where it does, it is split out at the main distribution board.

3 Phase Electricity Wave Form
One voltage cycle of a 3-phase electrical system, labeled 0 to 360 ( 2 π radians) along the time axis. The plotted line represents the variation of instantaneous voltage (or current) with respect to time. This cycle will repeat 50 or 60 times per second, depending on the power system frequency. The colors of the lines represent the American color code for three-phase. That is black=VL1 red=VL2 blue=VL3
3 Phase Power Wave

3 phase electricity 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).

3 Phase Electricity Wiring Color Coding
The 3 phases are typically indicated by colors which vary by country. See the table for more information.

Conductors of a three phase system are usually identified by a color code, to allow for balanced loading and to assure the correct phase rotation for induction motors. Colors used may adhere to old standards or to no standard at all, and may vary even within a single installation. However, the current National Electrical Code (2005) does not require any color identification of conductors other than that of the neutral (white or white with a color stripe) the ground (green or green with a yellow stripe) or in the case of a High Leg Delta system, the High Leg must be identified orange.  Read more on 3 Phase Wiring and Color Coding.

3 Phase Electricity Generation
At the power station, an electrical generator converts mechanical power into a set of alternating electric currents, one from each electromagnetic coil or winding of the generator. The currents are sinusoidal functions of time, all at the same frequency but with different phases. In a three-phase system the phases are spaced equally, giving a phase separation of 120. The frequency is typically 50 Hz in Europe and 60 Hz in the US (see List of countries with mains power plugs, voltages and frequencies).

3 Phase Electricity Distribution and Transmission
After numerous further conversions in the transmission and distribution network the power is finally transformed to the standard mains voltage (the voltage of "house" or "household" current in American English). The power may already have been split into single phase at this point or it may still be 3 phase. Where the step-down is 3 phase, the output of this transformer is usually star connected with the standard mains voltage (120 V in North America and 230 V in Europe) being the phase-neutral voltage. Another system commonly seen in the USA is to have a delta connected secondary with a center tap on one of the windings supplying the ground and neutral. This allows for 240 V three phase as well as three different single phase voltages (120 V between two of the phases and the neutral, 208 V between the third phase (known as a wild leg) and neutral and 240 V between any two phases) to be made available from the same supply.

3 Phase Electricity Calculation
The 3 phases are typically indicated by colors which vary by country. See the table for more information.

3 Phase Electricity Loads
The most important class of three-phase load is the electric motor. A three phase induction motor has a simple design, inherently high starting torque, and high efficiency. Such motors are applied in industry for pumps, fans, blowers, compressors, conveyor drives, and many other kinds of motor-driven equipment. A three-phase motor will be more compact and less costly than a single-phase motor of the same voltage class and rating; and single-phase AC motors above 10 HP (7.5 kW) are uncommon.

Large air conditioning equipment (for example, most York units above 2.5 tons (8.8 kW) cooling capacity) use three-phase motors for reasons of efficiency and economy.

Resistance heating loads such as electric boilers or space heating may be connected to three-phase systems. Electric lighting may also be similarly connected. These types of loads do not require the revolving magnetic field characteristic of three-phase motors but take advantage of the higher voltage and power level usually associated with three-phase distribution.

Large rectifier systems may have three-phase inputs; the resulting DC current is easier to filter (smooth) than the output of a single-phase rectifier. Such rectifiers may be used for battery charging, electrolysis processes such as aluminum production, or for operation of DC motors.

An interesting example of a three-phase load is the electric arc furnace used in steel making and in refining of ores.

In much of Europe stoves are designed to allow for a 3 phase feed. Usually the individual heating units are connected between phase and neutral to allow for connection to a single phase supply where this is all that is available.

3 Phase Loads on 1 Phase Power
The three phases are typically indicated by colors which vary by country. See the table for more information.

3 Phase Converters
Occasionally the advantages of three-phase motors make it worthwhile to convert single-phase power to 3 phase. Small customers, such as residential or farm properties may not have access to a three-phase supply, or may not want to pay for the extra cost of a three-phase service, but may still wish to use three-phase equipment. Such converters may also allow the frequency to be varied allowing speed control. Some locomotives are moving to multi-phase motors driven by such systems even though the incoming supply to a locomotive is nearly always either DC or single phase AC.

Because single-phase power is interrupted at each moment that the voltage crosses zero but three-phase delivers power continuously, any such converter must have a way to store energy for the necessary fraction of a second.

One method for using three-phase equipment on a single-phase supply is with a rotary phase converter, essentially a three-phase motor with special starting arrangements that produces a three-phase system. When properly designed these rotary converters can allow satisfactory operation of three-phase equipment such as machine tools on a single phase supply. In such a device, the energy storage is performed by the mechanical inertia (flywheel effect) of the rotating components.

Some devices are made which create an imitation three-phase from three-wire single phase supplies. This is done by creating a third "subphase" between the two live conductors, resulting in a phase separation of 180 - 90 = 90. Many three-phase devices will run on this configuration, but at lower efficiency.

Solid-state inverters also can be used to power three-phase motors from a single-phase supply.

The two main types of 1 phase to 3 phase converters are Rotary Phase Converters and Static Phase Converters.

3 Phase Frequency and Frequency Converters
The three phases are typically indicated by colors which vary by country. See the table for more information. The two main types of 1 phase to 3 phase converters are Rotary Phase Converters and Static Phase Converters.

1 Phase Loads on 3 Phase Power
Single-phase loads may be connected to a three-phase system, either by connecting across two live conductors (a phase-to-phase connection), or by connecting between a phase conductor and the system neutral, which is either connected to the center of the Y (star) secondary winding of the supply transformer, or is connected to the center one winding of a delta transformer (High leg Delta system). Single-phase loads should be distributed evenly between the phases of the three-phase system for efficient use of the supply transformer and supply conductors.

Additional 3 Phase Generator Information Sources:
Diesel Generators Diesel Power Generators Diesel Generator Sets Power Generators Onan Diesel Generators Kipor Diesel Generator Kubota Diesel Generator Cummins Diesel Generator Yanmar Diesel Generator

Continue And Read About Additional 3 Phase Power Details:

- 3 Phase Power Home
- 3 Phase Wiring
- 3 Phase Power Calculation
- 3 Phase Electricity
- 3 Phase Power Loads
- 3 Phase Power Converter
- 3 Phase Converters
  * Rotary Phase Converters
  * Static Phase Converters
- 3 Phase Generators
- 3 Phase Transformers
  * 3 Phase Isolation Transformers
- 3 Phase Motors
- 3 Phase Frequency
  * Frequency Converters
- 3 Phase Distribution
- 2 Phase Systems
- 1 Phase Loads on 3 Phase Power
- 3 Phase Loads on 1 Phase Power

Contribute 3 Phase Power Articles to The 3 Phase Power Resource Site:
If you would like to contribute additional 3 phase info to our 3 phase power resource site please feel free to email your 3 phase power article to us at info@3phasepower.org.  By doing so you are giving us full rights to edit and distribute the info freely worldwide in perpetuity in any way we see fit.  Note that The 3 Phase Power Resource Site is run by all volunteers and thus we do not have the ability to respond to all emails.  Also not all info submitted will be added to the site.  It is at the sole discretion of our electrical editors.  Thank you for contributing! 

 

Smooth 3 Phase Power Wave Form (center)
Because of its smooth wave length properties, 3 phase electrical power is used across the U.S. and throughout the world.



3 Phase Transformer

3 Phase Substation Transformer
(above)
There are a variety of 3 phase transformer types and voltages, depending on your power needs.


3 Phase Power Saw

3 Phase Power Saw (above)
There are a whole variety of power equipment and power tools which require 3 phase power to run.


TEMCo 3 Phase Converter

3 Phase Converter
(above)
Some Types of Rotary Phase Converters will run on 1 phase power and generate 3 phase power to run other 3 phase equipment.


 
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