What is 3 phase??

Question

What is 3 phase?? How does it differ from 2 phase??
Are they interconvertible?

Answer 1

Another answer in this column of responses is fairly close but I respectfully clarify.

3 phase AC power consists of 3 "hot" lines, above ground potential, that will each have the same nominal voltage with respect to ground.
I say ground, because not all 3 phase power will have a "neutral".

All 3 phase power will have sinusoidal ( sine wave ) alternating current ( AC ) that will each be 120 degrees apart from each other, on when in time, each phase peaks in its individual voltage swing. Remembering there is 360 total degrees in a circle.

There are 2 basic types of 3 phase power.

The first is called a Delta 3 phase and does not have a "neutral" line. This is a typical circuit for cross country power transmission and also local primary distribution for end customers.
Some commercial end customers will have equipment or machinery that require a Delta 3 phase supply for perhaps large electric motors or heating.
The connection for this Delta has 3 hot lines and a earth ground. In this instance - the power is utilized among the 3 phases and not referenced to a ground or neutral. (To keep this fairly simple, we won't go into 3 phase with a "wild leg" with one supply winding center tapped etc....)

The other common 3 phase is called Wye 3 phase.
This has 3 hot lines , a neutral line and a earth ground. This type of power source is designed not only to supply a 3 phase equipment requirement, but is commonly connected to use the neutral with one hot line , to supply a single phase need.
For example - a 208 volt 3 phase Wye supply will have a potential to connect a hot and neutral wires to standard outlets and lighting and have 120 VAC at the outlet.
The loads that are being drawn, on any of these 3 distinct phases need to be designed, to minimize neutral line flow. Severe inbalance between phases, and reactive loads, do have significant neutral line current flow.
Minor inbalance is normal and acceptable, and literally unavoidable because each phase will vary in flow depending if more or less lighting or outlets, are in use at any given time.

Another common Wye configuration is 480 VAC, which when referenced to neutral, have a voltage of 277 volt to neutral, on any phase. This is common in schools and industry etc.
Banks of lighting circuits, such as strings of flourescent lighting fixtures will be wired and use the 277 volts on each circuit. This permits more wattage on a circuit with a particular size of wire, than a typical 120 volt circuit.
A 208 VAC Wye 3 phase can normally be used phase to phase, as a supply to a load, that would perhaps normally be used on a normal SINGLE phase residential or light commercial power. Even though the phase to phase voltage in 208 volt systems is a bit lower than a single phase 240 volt/120 volt supply.

A typical residential or light commercial power is not called 2 phase.

This is a single phase source and the 3 transformer wires from the pole have 2 hots and a neutral. The neutral is derived from a center tapped pole transformer which when wired to the building's main breaker panel, has several things involved.
The neutral line, from the pole transformer is strapped to earth ground at this main panel.
Each of the 2 hots can be wired, along with a neutral line, in the branch circuit, to provide a 120 VAC supply for lighting and outlets etc.
Larger loads such as an electric dryer, hot water heater, large air conditioners etc, use both hot lines as the power source and will see 240 Volts - single phase - to operate the load.
This circuit may or may not have a neutral line....
( which would permit a 120 volt requirement to be fulfilled in a particular 240 volt appliance).

The 240/120 single phase transformers - on poles or located in vaults away from the pole, are connected to only one of the 3 phase primary power lines. The local utility attempts to balance their 3 phase distribution power, by hooking individual pole transformers, on various phases as the lines go from pole to pole throughout the service area.

HTH

Deric

Answer 2

3 phase system typically has 3 hot leads, a nuetral and a ground...The 3 phases can be connected to the nuetral to form three seperate circuits 120 degrees out of phase with each other...

2 phase system is the same thing with 2 hot leads...a 240 volt connection in your house for a high current appliance might be typically hooked up to a 2 phase supply...You can use two of the three hots from a three phase system to power a two phase device. However, the system will not be balanced because the load is on two of the three circuits. This means you will typically have a little current on the nuetral connection...

Answer 3

definite, you could run unmarried section kit from a three section source less than particular circumstances. however, that's needed to examine the voltage and/or phasing criteria of kit to the accessible source for the secure operation of suggested kit. on your case, although, it isn't accessible to run a three section welder from a unmarried section source and not using slightly convertor. This gadget alters the sine wave of unmarried section to "simulate" 3 section sine wave. it truly is straightforward idea. in case you or your opposite numbers do not comprehend the needed principals of electrical energy and electric powered idea, for heavens sake, discover yet another line of work earlier you kill your self or some different person.

Answer 4

Three-phase electric power is a common method of alternating-current electric power generation, transmission, and distribution. It is a type of polyphase system and is the most common method used by electrical grids worldwide to transfer power. It is also used to power large motors and other heavy loads.

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