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Single phase requires 2 wires - a hot, and a return (both wires of the same size. Three phase requires three (same size), and if it is grounded will require a forth (doesn't normally carry current so it can be small). Two phase requires three wires (two phase conductors of one size, and a return that can handle double the current of the phase conductors), or four wires (same size for all, effectively two separate single phase supplies).

It isn't economical is the bottom line. It costs ~the same (in wire) for two phase as three, and you get 50% more power delivering capability with three phase.

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Q: Why you use only single phase and three phase supply?
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Can you run a three phase motor with single phase generator with help of phase converter?

Terminology gets misapplied but a 3-phase converter produces a 3 phase supply from a single phase supply. The only proviso is that generator, converter and motor are all suitably rated and compatible.


Does DC have a single phase and a three phase supply?

No, there is not. Three phase ,or generally speaking multiphase, circuits are available only for AC (alternating current) systems, because there is no phase shift in DC (direct current) systems. This is because DC power is not sinusoidal (current flows in one direction).


What will happen if apply two phase supply to a three phase transformer?

A three phase transformer is simply three transformers so, supplying one phase to a set of three transformers will result in only one phase output. Any loads connected to that transformer that are expecting three phase power will malfunction, and could fail.AnswerA three-phase transformer is NOT 'three separate single-phase transformers', as suggested in the original answer. It is a single transformer with three primary and secondary phase-windings wound around a common three-limb ('core') or five-limb ('shell') core. If a single-phase supply was applied to one of the three primary windings, then single phase voltages would appear across each of the three secondary windings and the remaining two primary windings. These voltages would not be out of phase with each other.


Can you connect a 3 phase motor to a 1 phase supply?

Single phase to three phaseThe physical internal windings between single phase and three phase motors makes this an impossibility That being said money can make anything happen. Depending on the amount of money you want to spend to make this happen there is a device on the market called a VFD ( Variable Frequency Drive). On the three phase input terminals you apply your single phase voltage. On the output terminals you connect your three phase motor. When run in this configuration there is an internal switch that has to be changed to let the VFD know that it should be looking for only two lines on the input to be hot. Other wise the VFD thinks that there is a line loss on the three phase input terminals and the unit will not start.Some 3 phase motor speed controllers can be run off a single phase supply, this caused us a problem at work when a new speed control was fitted to some laundry equipment, as we then had to rewire the supply to bring in a nuetral, so i suggest a speed controller is probably the solution.


What will happen if dc supply given to a single phase ac motor?

There actually is no such thing as 2 phase. You either have single phase (As most/all residential services), or three phase (primarily in commercial/industrial). When a normal three phase motor 'loses a phase' (blown fuses, open winding, bad contactor, etc...) if it continues to operate, it is considered 'single phasing'. While such operation is typically only briefly. (They usually don't run long) While it probably will not operate very long, the motor would over heat, and loose speed rapidly, and they will sometimes make noise. If you need to operate a three phase motor on residential service, you will need a 'three phase converter' (some people call them 'inverter's) to electronically convert single phase power into three phase, but they are usually only practical for smaller three phase motors.

Related questions

How do you use a one phase motor in place of a three phase motor?

To use a single/one phase motor instead of a three phase motor is possible if you have a three phase power supply as you will only need to tap one of the three phases together with neutral and an earthwire, however to use a three phase motor instead of a single phase will require the provision of three phase power supply.


Can you run a three phase motor with single phase generator with help of phase converter?

Terminology gets misapplied but a 3-phase converter produces a 3 phase supply from a single phase supply. The only proviso is that generator, converter and motor are all suitably rated and compatible.


Two phase instruments?

There is no such thing as a two phase instrument. There is only single phase and three phase. You can only have: single phase/ one pole single phase/ two pole three phase/ three pole


How can you get 3 phase supply from single phase supply by using only transformers?

You cannot. By definition, the potential of each line must be displaced from each other by 120 electrical degrees, and this is only achievable from a three-phase source.


You have one hp three phase motor where as available power supply is only single phase how can you run this motor?

You will need to install a phase converter or change the motor to single phase. You can find a licensed electrician at www.contraxtor.com


Does DC have a single phase and a three phase supply?

No, there is not. Three phase ,or generally speaking multiphase, circuits are available only for AC (alternating current) systems, because there is no phase shift in DC (direct current) systems. This is because DC power is not sinusoidal (current flows in one direction).


Why three-phase rectifier is preferred upon single-phase rectifier?

The choice of single or three phase depends on the available supply. But a three-phase full wave rectifier provides 6 pulses of DC per cycle, while a single-phase full-wave rectifier provides only two. That makes the output DC easier to smooth.


Why you use three phase supply in experiment of power factor of RL series circuit?

You don't necessarily. For a straightforward series (or parallel) R-L load, you will only require a single-phase supply. However, if you had three R-L loads, connected in delta or star (wye), then you would require a three-phase supply.


What will happen if apply two phase supply to a three phase transformer?

A three phase transformer is simply three transformers so, supplying one phase to a set of three transformers will result in only one phase output. Any loads connected to that transformer that are expecting three phase power will malfunction, and could fail.AnswerA three-phase transformer is NOT 'three separate single-phase transformers', as suggested in the original answer. It is a single transformer with three primary and secondary phase-windings wound around a common three-limb ('core') or five-limb ('shell') core. If a single-phase supply was applied to one of the three primary windings, then single phase voltages would appear across each of the three secondary windings and the remaining two primary windings. These voltages would not be out of phase with each other.


How do you plug single phase 208 into three phase 480 commercial power supply?

only use one pole. you should definitely refer to the manufacturer's schematics


What cannot be considered a single phase?

Any load that needs three legs from a three phase system can not be considered single phase. Single phase from a three phase system only needs a connection to two legs.


How do you know whether the supply is single phase or three phase?

Use a volt meter and measure between phases. Look at the main and if it has 3 hots then it is three phase. Brown orange yellow or Black Red Blue. If you only have 2 lines feeding the panel then it 3 wire single phase. Hope that helps.