# What Is The Difference Between Single Phase And Three Phase Electricity?

Single-phase electricity, usually supplied at 220 to 240 Volts, is mainly used in domestic properties, where loads consist mostly of heating and lighting, with only few large electric motors.
In a single-phase distribution system, all voltages of the alternating current supplied vary simultaneously and services are rated at 100 Amps maximum. Single-phase electricity always has a neutral wire.
Three-phase electricity is supplied at 400 to 440 Volts and is rated at 300 Amps; 100 Amps per phase. The three phases do not reach their peak value at the same time, but are offset in time.
Within every cycle of the power frequency, each conductor, or phase, reaches its maximum value in turn, delayed by one third of the period from the previous one.
This delay results in a more or less constant transfer of power over every circle and enables the production of rotating magnetic fields in electric motors.
This, and the higher voltages possible, makes it most suitable for industrial use. In some cases, a neutral wire may be included in a three-phase system, allowing the use of higher voltages, while still being able to support single-phase appliances of lower voltage.
In high voltage, industrial settings, a neutral wire is not usually present and loads are connected phase to phase. If transferred to balanced loads, it aids in the reduction of motor/generator vibration.
Three-phase electricity may lead to domestic properties, but is usually connected to households in single-phase, with each phase being brought into a separate house.
As a rule, three-phase does not lead directly into domestic properties. If it does, it is normally split at the main distribution point, feeding individual loads single phase.
Occasionally, three-phase electricity is used to power electric clothes dryers, cookers or electric stoves.
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Single phase i.e the current we generally use in our houses and for simple and less loaded devices and instruments. The current in this is of capacity 230v,ac. Where as the three phase carries a current of 415volts. One major factor that is considered is that The three phase generates 1.73 times more current as compared to single phase. As far the three phase induction motors are concerned, they give a constant torque all round its rotation. But in single phase induction motors they produce an impulsive torque around its rotation. Thanx...... "Dipesh:"
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Single phase power is a single AC sine-wave power source, that peaks at 1.414 times the RMS value, then falls and crosses zero, and reverses to -1.414 times the RMS value during the negative half cycle before repeating.  It uses a single hot conductor and a neutral return wire.

Three phase power consists of power produced by three sine-waves, 120 degrees apart from each other.  At any given time, if one phase is at zero volts during a crossover, the other two are still producing instantaneous power. There are two configurations; Four wire Wye and Three wire Delta.  Sometimes Delta has an additional center tap to provide another voltage.  For some types of loads, particularly large motors, three phase has significant benefits to deliver power.

see
en.wikipedia.org

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