what are the differences and application (in simple terms) between a single and double phase power supply?

Question

what are the differences and application (in simple terms) between a single and double phase power supply?

Answer 1

A two phase system is used when the load of the establishment is too large for a single phase system.



It is a three wire system with two actives and one neutral



The voltages between phases is still 400 volts and the phase to neutral voltage is 230 volts. These are the current Australian nominal voltages.



The phases are 120 degrees apart.



If you had a large house that was drawing over about 100 amps the supply authority would probably require you to run in another phase in from the supply.



The load would then be split across phases. I.e. half the house would be between A phase and neutral the other half between b phase and neutral.



Often they require the stove to have two phases and neutral supply with half the stove on a phase and neutral the other half on b phase and neutral.



If you had a single phase 400 volt welder it could be connected between a phase and b phase.



If you have a really big house then you may require a three phase and neutral supply (4 wire) system.

Answer 2

What exactly is your question? Are you asking for the difference between single phase and three phase power? Or the difference between a power supply that take a single phase input versus one that takes a three phase input?

Answer 3

I've only heard of single & 3-phase power in application. single phase is usually AC rectified for just DC voltage. 3 phase might be used for ac supply. 2-phase seems like it's not used...

Answer 4

Three-phase electric power is a common method of alternating-current electric power transmission.[1] It is a type of polyphase system, and is the most common method used by electric power distribution grids worldwide to distribute power. It is also used to power large motors and other large loads. A three-phase system is generally more economical than others because it uses less conductor material to transmit electric power than equivalent single-phase or two-phase systems at the same voltage.[2]



In a three-phase system, three circuit conductors carry three alternating currents (of the same frequency) which reach their instantaneous peak values at different times. Taking one conductor as the reference, the other two currents are delayed in time by one-third and two-thirds of one cycle of the electrical current. This delay between "phases" has the effect of giving constant power transfer over each cycle of the current, and also makes it possible to produce a rotating magnetic field in an electric motor.



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:



The phase currents tend to cancel out one another, summing to zero in the case of a linear balanced load. This makes it possible to eliminate or reduce the size of the neutral conductor; all the phase conductors carry the same current and so can be the same size, for a balanced load.

Power transfer into a linear balanced load is constant, which helps to reduce generator and motor vibrations.

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 household loads are single-phase. In North America and some other countries, three-phase power generally does not enter homes. Even in areas where it does, it is typically split out at the main distribution board and the individual loads are fed off a "single" phase.



The three phases are typically indicated by colors which vary by country. See the table for more information.

Answer 5

Single phase and double phase can be confusing.

They are sometimes used to refer to the same thing.



In most homes there are two lines of power coming in from the street. These can be referred to as phases. Both lines have 120 volts, but they are 180 degrees out of phase with each other. This is how you get 240 volts.



AC stands for alternating current. The power cycles from positive 120V to negative 120V 60 times every second. When one phase is positive 120, the other is negative 120. The difference between positive 120 and negative 120 is 240. Yes, there are times when they are both zero, but the cycle happens so quickly that this cannot be seen without very expensive equipment.



To better help answer the question, singe and double phase can be better described as single and double pole. Single pole refers to one leg of power. Double pole refers to two legs of power.



Things such as lighting and outlets almost always operate on a single pole, 120V. Things like water heaters, stoves, dryers, and A/C units usually operate on double pole circuits, 240V.

Answer 6

Two-phase electrical power was an early 20th century polyphase alternating current electric power distribution system. Two circuits were used, with voltage phases differing by 90 degrees. Usually circuits used four wires, two for each phase. Less frequently, three wires were used, with a common wire with a larger-diameter conductor. Some early two-phase generators had two complete rotor and field assemblies, with windings physically offset by 90 electrical degrees to provide two-phase power. The generators at Niagara Falls installed in 1895 were the largest generators in the world at the time and were two-phase machines.



The advantage of two-phase electrical power was that it allowed for simple, self-starting electric motors. In the early days of electrical engineering, it was easier to analyze and design two-phase systems where the phases were completely separated. [1] It was not until the invention of the method of symmetrical components in 1918 that polyphase power systems had a convenient mathematical tool for describing unbalanced load cases. The revolving magnetic field produced with a two-phase system allowed electric motors to provide torque from zero motor speed, which was not possible with a single-phase induction motor (without extra starting means). Induction motors designed for two-phase operation use the same winding configuration as capacitor start single-phase motors.

Two-phase circuits typically use two separate pairs of current-carrying conductors. Alternatively, three wires may be used, but the common conductor carries the vector sum of the phase currents, which requires a larger conductor. Three phase can share conductors so that the three phases can be carried on three conductors of the same size. In electrical power distribution, a requirement of only three conductors rather than four represented a considerable distribution-wire cost savings due to the expense of conductors and installation.



Two-phase power can be derived from a three-phase source using two transformers in a Scott connection. One transformer primary is connected across two phases of the supply. The second transformer is connected to a center-tap of the first transformer, and is wound for 86.6% of the phase-to-phase voltage on the 3-phase system. The secondaries of the transformers will have two phases 90 degrees apart in time, and a balanced two-phase load will be evenly balanced over the three supply phases.



Three-wire, 120/240 volt single phase power used in the USA and Canada is sometimes incorrectly called "two-phase". The proper term is split phase or 3-wire single-phase.