why 3 phase why not 4 or 5 phase

why power generation is done in 3 phase why power generation is not done in 4 phase or 5 phase

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23 Answers
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  • For3 Phase system the phase angel between transmission line is360/3=120 Degree. As the number of phase increases the phase difference will decrease and more number of times transposition is required. It affects the Installation cost of transmission of Transmission towers.

     
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  • First of all for new technology we have to create device to bear it so 3 phase is just because it is so economial than 4phase nad 5 phase and no device is developed yet to apply 4 phase and 5 phase on it
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  • Going from 1 phase to 3 phase gives efficient improvement by 50% increase (which can be utilized toward reduced copper by 75%). Increasing the number of phases arbitrary more than that (infinite) can only increase efficiency very little (something of the order of 7%). This is efficiency comparison only. In any case, using 3 phase, you can get 3 times the power of the single phase (if you generate same voltage and current in any one phase as that of a 1 phase generator) and so on.
    Also analyzing for higher phases, in multiples of 3 i.e. 6,12 or higher lines, power transfer curve would be dropping e.g. 6 phases would add twice power than three phases but 12 phases do not add power double than that of 6 phases. Also higher phases would cause more constrain at grid.
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  • if talk about current distribution and generation infrastructure of India it is set for 3 phase and to increase the phase we need to change generator structure beside that main problem is to transmit six/nine  phase will require increased conductor, pole structure cost and all protecting equipements, transformer and thus very difficult to monitor every phase and to lacate fault also thus 3 phase is most economical, less complex and transfers adequate power
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  • Let's start with 2 phase why not 2 phase ? for 2 phase there need to be 2 alternator to be operated in parallel. As in 3 phase power transmitted is more than 2 phase. So 2 phase supply is not preferred. Now for 4 phase, or 6 phase we need 4 or 6 alternators to be operated in parallel and the generation region is large. As these alternators are installed at large places and measures are taken for their cooling also. So generation region required in 4 or 6 phase is large.. So 3 phase is the only optimal solution.
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  • economically and performnce based 3 phase is better than other poly phase systems so that's why we prefer 3phase system
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  • Because in case of three phase system generator losses will be minimum and generator can give maximum power
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  • because of to reduce the conductor size. whenever you use 4or 5 phase there have 4or5 conductors so only use 3phase. these 3phase to Cary the voltage has large. We use more voltage to transmit by using HVDC system.
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  • Hey Brother!! I too had the same doubt, but my teacher said that, 1&3 phases has more efficient power transmission and easy to convert voltage levels. Maybe that's why global standards use only 1&3 phases.
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  • 3 phase system is more economical and it damped out the even harmonics of the system
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  • 1 to produce rotational magnatic feild we need at lease tree phase its like shaire we can not make stable shair with one or two stand we need at least3 , sow in electrical enginiring we use three becouse its its the best between choises less phase mean less complication and moore economic
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  • because three phase is much economic than the other distribution and there are less transmission losses
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  • Three phase is most suitable
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  • Why we cannot use 6 phase supply instead of 3 phase supply? AnswerRequest Follow1 4 ANSWERS Avinash Kumar Avinash Kumar Written Oct 22, 2015 Thanks for A2A. Basically We can use 6 phase and in fact it is being used in certain research laboratories involved in particle physics and stuff. Experiments were done upto 12 phase. For explanation of why 6 phase is limited to special cases and not common in day today life - kindly look at this post Why are there only 3-phase electrical power systems? why not 6-phase, 9-phase, 12-phase, or some other number of phases? 717 Views · View Upvotes · Answer requested by Mohammed Ziya Upvote2 Downvote Share Sai SunilComment...RecommendedAll Robert Harvey Robert Harvey Written Sep 18, 2016 Economics. You can build polyphase systems with as many poles as you like. Some stepper motors use 4phases (of course, they aren't sinusoidal either, but that's another story). Some synchro systems used as compass repeaters on ships etc. use 6, largely for reasons of backwards compatibility with early devices. Polyphase systems are a trick to transfer the rotating magnetic field inside one device (the generator) to another (the motor). The minimum number of wires to do this is 3, and since wires cost money we use the minimum. 2 won't do it, because there is a 180 degree ambiguity in two wires. A single phase induction motor will run equally well in either direction. (Single phase induction motors have some sort of local gadget to make them start, such as a phase shift capacitor, and that chooses one direction. Remove it and start them by flicking and they can go either way)
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  • You can do it in 4 or 5 phase, but there is only a slight change in terms of efficiency. By comparing the cost of making 4 or 5 phase and the efficiency it gives, it's not feasable in the industry. So 3 phase is the ideal one.
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  • when three phase ac supply to the stator winding
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  • To maintain the phase shift of 120 electrical degree between the phases three phase will balance the structure of delta or star connection.
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  • bcoz each phases has 120 angle.
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