What is difference between three phase and single phase?
In electrical engineering, single-phase electric power refers to the distribution of alternating current electric power using a system in which all the voltages of the supply vary in unison. Single-phase distribution is used when loads are mostly lighting and heating, with few large electric motors. A single-phase supply connected to an alternating current electric motor does not produce a revolving magnetic field; single-phase motors need additional circuits for starting, and such motors are uncommon above 10 or 20 kW in rating.
In contrast, in a three-phase system, the currents in each conductor reach their peak instantaneous values sequentially, not simultaneously; in each cycle of the power frequency, first one, then the second, then the third current reaches its maximum value. The waveforms of the three supply conductors are offset from one another in time (delayed in phase) by one-third of their period.
Standard frequencies of single-phase power systems are either 50 or 60 Hz. Special single-phase traction power networks may operate at 16.67 Hz or other frequencies to power electric railways.
Three-phase electric power is a common method of alternating-current electric power generation, transmission, and is a type of polyphase system and is the most common method used by grids worldwide to transfer power. It is also used to power large motors and other heavy 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.[The three-phase system was introduced and patented by Nikola Tesla in 1887 and 1888.
Three-phase has properties that make it very desirable in electric power systems:
1) 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.
2) Power transfer into a linear balanced load is constant, which helps to reduce generator and motor vibrations.
3) 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.
**Single phase and three phase are the parameters in electricity... Single phase has a voltage rating of 220-230v wit 50 Hz freq in India. And three phase is 415v wit 50 Hz freq India.
Well in single phase there is one phase and one neutral i.e. P and N while in three phase there are three phases i.e.R,Y,B and a neutral both are dislaced by 120°each.
This is the main difference between single and three phase. And in three phase there are two ways to connect the three phases one is star and another one is delta. In star each phases of one end are connected at one point which forms neutral. In delta each phase is connected to end of other phases so thus it forms a closed path with no neutral.
Three phase is economical in operation and used in transmission and large machineries,while house holds use single phase.
