Why only we use 3 phase why not 5 phase
I really don’t know why we are stick up to 3 phase alternator I don’t believe it is constructional limitation
What are the reasons for limiting up to 3 phase alternator we say 3 phase is more efficient then single phase the why don’t we use 5 phase I can say 4 phase may produce flux which cancel out each other if we connect it all together in 5 phase motor.
Yes it is probably more costly in distribution but we can use such alternators as locomotive generators which supply several DC motors for traction.
What are the pro and cons of this system????
What are the reasons for limiting up to 3 phase alternator we say 3 phase is more efficient then single phase the why don’t we use 5 phase I can say 4 phase may produce flux which cancel out each other if we connect it all together in 5 phase motor.
Yes it is probably more costly in distribution but we can use such alternators as locomotive generators which supply several DC motors for traction.
What are the pro and cons of this system????
Replies

Anand TamariyaDid you try figuring out why 3phase is more efficient than single phase?

Akhilesh Kumar Nair
Yes, single phase only produce periodic flux but 3 phase produce rotating flux inside machine which gives various advantages for 3 phase like selfstaring size reduction because of more efficient winding etc. and that can also be obtained from 5 phase also but I am only talking about coupling of 2 or 3 (machines that can be DC) with a 5 phase generator as I mentioned in the above not challenging the whole international distribution systemAnand TamariyaDid you try figuring out why 3phase is more efficient than single phase? 
Saandeep SreerambatlaAs far as i know, when we use 3 phase power, what happens is always one of the three phases in nearing a peak, high power motors and some other welding machines therefore has an even power output. So we use 3 phase.
The angle shift is 120 between all the phases, if you take 5 phase the angle shift will be 72, and sine doesnt reach it maximum peak value at any time on any single phase which will not efficiently deliver output.
This is my understanding, correct me if i am missing anything! 
Akhilesh Kumar Nair
That is because the rotation of a magnetic field or rotor inside the stator.Saandeep SreerambatlaAs far as i know, when we use 3 phase power, what happens is always one of the three phases in nearing a peak, high power motors and some other welding machines therefore has an even power output. So we use 3 phase.
The angle shift is 120 between all the phases, if you take 5 phase the angle shift will be 72, and sine doesnt reach it maximum peak value at any time on any single phase which will not efficiently deliver output.
This is my understanding, correct me if i am missing anything!
In simple word the magnetic field cuts the coils in the stator such that the pole tip (where maximum magnetic strength is available) rotates such that coil near at that instant reach the maximum and the coil geometrically opposite will reach negative maximum and forms sinusoidal wave form.
It will happen the same in 5 phase as it only increase no coil division and reduce phase difference to 72 but remember individual phases will be unaffected and will give sine wave as before…. 
yogi.bharadwajhello Saandeep Sreerambatla says that in 3 phase supply sine is on its higer value but sin72>sin120 then whats the reason 5 phase supply would be more efficient because it can produve rotating flux with greater potentiall.
then whats the reason? 
Akhilesh Kumar Nair
I do not get your point but I want to clear that the phase difference will not affect individual induced voltage in different coils (even if we are using single phase or two phase) the individual phase will reach maximum when d (phy) /dt is maximum for a coil.yogi.bharadwajhello Saandeep Sreerambatla says that in 3 phase supply sine is on its higer value but sin72>sin120 then whats the reason 5 phase supply would be more efficient because it can produve rotating flux with greater potentiall.
then whats the reason?
This also happens in single and double phase machine but they only do not produce rotating magnetic field inside machine so they are less efficient….
If we say sin 120 or 72 it will be the position at which the next phase will start from zero……
I know it silly and already tried protocol but want the reason of it non existence… 
Jeffrey Arulraj
Sine 90 is the maximum point of a sine curveyogi.bharadwajhello Saandeep Sreerambatla says that in 3 phase supply sine is on its higer value but sin72>sin120 then whats the reason 5 phase supply would be more efficient because it can produve rotating flux with greater potentiall.
then whats the reason?
When we divide the whole wave that is 360 by 5 we have angle only upto 72. whereby the 90 degree point is skipped
Now do you get the need for the 3 phase supply 
Akhilesh Kumar Nair
What do you mean by dividing by 5?Jeffrey SamuelSine 90 is the maximum point of a sine curve and when we divide it by 5 we have angle only upto 72 whereby the 90 degree point is skipped
Now do you get the need for the 3 phase supply
Do me a favor read the above discussion and please don’t comment as FB status.
And if you want phase difference of 90 degree between phases then to obtain it you need 4 phases it is even not obtained in 3 phase…… 
Jeffrey ArulrajAkhilesh Kumar NairWhat do you mean by dividing by 5?
Do me a favor read the above discussion and please don’t comment as FB status.
And if you want phase difference of 90 degree between phases then to obtain it you need 4 phases it is even not obtained in 3 phase……
I edited check it
And by the by The maximum phase change attainable is 72 in 5 phase supply
That is what I meant
And not other way around
So we go for 3 phase supply Where the maximum
PS: I read before posting always
Just be yourself I Was not clear there And Thanks for pointing my error 
Akhilesh Kumar Nair
Ok then tell me what is befit of phase difference at least when I am using all 5 phases separately as single phase with a neutral and if it is of so much important then why not 2 phase are used with more phase difference of 180…..Jeffrey SamuelI edited check it
And by the by The maximum phase change attainable is 72 in 5 phase supply
That is what I meant
And not other way around
So we go for 3 phase supply Where the maximum
PS: I read before posting always
Just be yourself I Was not clear there And Thanks for pointing my error 
Jeffrey ArulrajNice question
When phase difference is 120 degree one of the sine wave reaches maximum voltage at any point of time
That is why we go for three phase
When in the case of 2 phase the phase difference is 180 degree In this condition we will have ZERO amplitude when angle is 0 degree
This is because sin 0=sin180=0
So we don't go for 2 phase supply 
Akhilesh Kumar Nair
Ok I am tired of this but I want explain it once again for you thatJeffrey SamuelNice question
When phase difference is 120 degree one of the sine wave reaches maximum voltage at any point of time
That is why we go for three phase
When in the case of 2 phase the phase difference is 180 degree In this condition we will have ZERO amplitude when angle is 0 degree
This is because sin 0=sin180=0
So we don't go for 2 phase supply
The maximum will be reached by sine wave of one phase will at 72 and after 72 other by phase as it is reached in 3 phase at 120……
The induced voltage in individual phase will be independent of phase shift and will have of sinusoidal nature given by faradays law but that angle of sinusoidal function is not the phase angle…..
And please concentrate that my priority is for generator of 5 phase first ….. 
Saandeep SreerambatlaEven phases are not used because the resulting neutral wire has to carry large amount of power in case of any faults.
Please be patient while posting the comments. You never know what a person is thinking. So be professional... 
yogi.bharadwaj
[
 #LinkSnipped# Moderator
Engineering Discipline:
Electrical
Even phases are not used because the resulting neutral wire has to carry large amount of power in case of any faults.
Please be patient while posting the comments. You never know what a person is thinking. So be professional...
**ES**
 #LinkSnipped# Moderator

Akhilesh Kumar Nair
For me it is hard to guess to whom you are directing but I believe I posted some reply which may be arrogant in sense but I really not intended.Saandeep SreerambatlaEven phases are not used because the resulting neutral wire has to carry large amount of power in case of any faults.
Please be patient while posting the comments. You never know what a person is thinking. So be professional...
This discussion is might be kidding in hearing but I am serious about it…
And I was asking for 5 phase which is odd and I mentioned in my initial question or first post that I am not considering 4 phase(even phase) because other than the problem you highlighted it will cancel out magnetic effect of each other if they connected to 4 phase(even phase) Motor…. 
Anand Tamariya
That's not the reason. Means of production is only to ensure efficient distribution. You should figure out why it's more efficient to distribute polyphase power. Then you can do a comparison between 3 and 5 phase distribution systems while keeping in mind to balance efficiency improvement against increased manufacturing cost.Akhilesh Kumar NairYes, single phase only produce periodic flux but 3 phase produce rotating flux inside machine which gives various advantages for 3 phase like selfstaring size reduction because of more efficient winding etc. and that can also be obtained from 5 phase also but I am only talking about coupling of 2 or 3 (machines that can be DC) with a 5 phase generator as I mentioned in the above not challenging the whole international distribution system 
Akhilesh Kumar Nair
First thing I am not challenging entire 3 phase distribution systemAnand TamariyaThat's not the reason. Means of production is only to ensure efficient distribution. You should figure out why it's more efficient to distribute polyphase power. Then you can do a comparison between 3 and 5 phase distribution systems while keeping in mind to balance efficiency improvement against increased manufacturing cost.
And I am aware that we get optimal distribution system using 3 phase system which is also balanced that all you highlighted like more wiring and more cores for transformer etc. and yes it will be just increase principle cost of distribution with negligible effect in load distribution and which can be take cared by 3 phase itself vary at less price………
BUT
I am taking only a group which is consist of one 5 phase generator and 2 or 3 motor coupled to it so my question is just limited to the construction of a 5 phase generator that such thing is constructedalready or tested away and if it possible then it will have advantage or disadvantage when coupled to motor only …..
And thank you for your time in involving with me 
Akhilesh Kumar Nair
First thing I am not challenging entire 3 phase distribution systemAnand TamariyaThat's not the reason. Means of production is only to ensure efficient distribution. You should figure out why it's more efficient to distribute polyphase power. Then you can do a comparison between 3 and 5 phase distribution systems while keeping in mind to balance efficiency improvement against increased manufacturing cost.
And I am aware that we get optimal distribution system using 3 phase system which is also balanced that all you highlighted like more wiring and more cores for transformer etc. and yes it will be just increase principle cost of distribution with negligible effect in load distribution and which are taken cared by 3 phase at vary at less price………
BUT
I am taking only a group which is consist of one 5 phase generator and 2 or 3 motor coupled to it so my question is just limited to the construction of a 5 phase generator that such thing is constructedalready or tested away and if it possible then it will have advantage or disadvantage when coupled to motor only …..
And thank you for your time in involving with me 
Halil Alper ONAYLet me ask Why there is no 4phase or the power of 2 phase ?

Akhilesh Kumar Nair
You can have any no phases you only have to divide your winding in the generator but when you choose even phase it will have problem when it is connected to motor of same no of phase as magnetic field produced by it will not produce useful flux they cancel out each otherHalil Alper ONAYLet me ask Why there is no 4phase or the power of 2 phase ? 
Akhilesh Kumar Nair
and even if you are using all phase separately for even phase then also you will have no problem using such way....Akhilesh Kumar NairYou can have any no phases you only have to divide your winding in the generator but when you choose even phase it will have problem when it is connected to motor of same no of phase as magnetic field produced by it will not produce useful flux they cancel out each other 
Halil Alper ONAY
I see but I think it is not even numbers that cause actual problems but the power of two phases. I have encountered with such even phases like 6,12 but I have never seen phases such as 4,8 or 16.Akhilesh Kumar NairYou can have any no phases you only have to divide your winding in the generator but when you choose even phase it will have problem when it is connected to motor of same no of phase as magnetic field produced by it will not produce useful flux they cancel out each other 
Akhilesh Kumar Nair
It amazing brother and I am queries to know about 6 and 12 phases but in my machine study I never faced such protocol if there is something done like that in electronic circuits….and if done then I have these doubts…..Halil Alper ONAYI see but I think it is not even numbers that cause actual problems but the power of two phases. I have encountered with such even phases like 6,12 but I have never seen phases such as 4,8 or 16.
If it is only done by using inductor and capacitor arrangement to make phase shift or you use some dynamic machine like alternator or something like that?
What is the need of 6 and 12 phase?
If there any practical application currently based on 6 and 12 phase?
And it will be more helpful for me if share me that how you get power of two phases is a problem in with respect alternator as far as I imagine power in each phases will be equal if windings are equally distributed for different phases and I am not pulling you back to of even phase I just want to know your abstraction on relation between phase and power…. 
Anand Tamariya
I'm sure 5 phase generator would have been constructed. But it never left lab and went into production because it didn't win the utility improvement over production cost.Akhilesh Kumar NairBUT
I am taking only a group which is consist of one 5 phase generator and 2 or 3 motor coupled to it so my question is just limited to the construction of a 5 phase generator that such thing is constructedalready or tested away and if it possible then it will have advantage or disadvantage when coupled to motor only …..
And thank you for your time in involving with me 
Ahsanul haqueThreephase😉 electric power is a common method of alternatingcurrent electric power generation, transmission, and distribution. It is a type of polyphase system and is the most common method used by electrical grids worldwide to transfer power. It is also used to power 👍large motors and other heavy loads. A threephase system is usually more economical than an equivalent singlephase or twophase system at the same voltage because it uses less conductor material to transmit electrical power. 👍Aluminium melting industry uses 48 phase for melting👍. If you want to calculate phase and #LinkSnipped# . Thanks Akhilesh Kumer Nair . Helpful links. Seeking Question and ask Question Both have a Scientist/Eng. Habbit. Thanks again

Akhilesh Kumar Nair
At least I have a hope now ….thank youAnand TamariyaI'm sure 5 phase generator would have been constructed. But it never left lab and went into production because it didn't win the utility improvement over production cost. 
Akhilesh Kumar Nair
If you mean 48 electrical Phase for melting an aluminum as you mentionedAhsanul haqueThreephase😉 electric power is a common method of alternatingcurrent electric power generation, transmission, and distribution. It is a type of polyphase system and is the most common method used by electrical grids worldwide to transfer power. It is also used to power 👍large motors and other heavy loads. A threephase system is usually more economical than an equivalent singlephase or twophase system at the same voltage because it uses less conductor material to transmit electrical power. 👍Aluminium melting industry uses 48 phase for melting👍. If you want to calculate phase and #LinkSnipped# . Thanks Akhilesh Kumer Nair . Helpful links. Seeking Question and ask Question Both have a Scientist/Eng. Habbit. Thanks again
Would you please visualize me this â€¦. I really do not have any Idea about that ???? 
Ahsanul haque
you could check out this siteAkhilesh Kumar NairIf you mean 48 electrical Phase for melting an aluminum as you mentioned
Would you please visualize me this â€¦. I really do not have any Idea about that ????
Aluminium 😁 
sumiijaisican anyone tell me why single phase is 220 volts and three phase is 440 although its 3 times so it may be 660 volts... sometimes i listen single phase is 120v... i am a bit confused.... can anyone explain please..??

Akhilesh Kumar Nair
Brother its take some time to get you this point but I will advise you to first find out line & phase parameters and there interrelationships then you will know that during phase to line conversion the factor of multiplication is rut 3 not 3,if you don't get the point in the way I explained then inform me I will try to explain...sumiijaisican anyone tell me why single phase is 220 volts and three phase is 440 although its 3 times so it may be 660 volts... sometimes i listen single phase is 120v... i am a bit confused.... can anyone explain please..??
and thanks for asking this question. 
Akhilesh Kumar Nair
sorry bro I failed to find on that page about phases, can you just upload the screenshots of the point that you want to show....please.Ahsanul haqueyou could check out this site
Aluminium 😁 
Ahsanul haqueAccording 3 phase and single Phase devices can be powered from a 3 phase supply. 3 phase circuit is a combination of 3 singlephase circuits. The current, voltage, and power relations of balanced threephase AC circuits can be studied by applying the rules that apply to singlephase circuits. And I wrote a Article about #LinkSnipped# Thanks.

Akhilesh Kumar Nair
I couldnâ€™t find any relation of this with my question as you all that you mentioned above is all about 3 and 1 phase but I was interested in 5 phase alternator construction neither transmission or circuit study of single or 3 phase and in last question I was asking about 48 electrical phase that found on that link to melt aluminiumAhsanul haqueAccording 3 phase and single Phase devices can be powered from a 3 phase supply. 3 phase circuit is a combination of 3 singlephase circuits. The current, voltage, and power relations of balanced threephase AC circuits can be studied by applying the rules that apply to singlephase circuits. And I wrote a Article about #LinkSnipped# Thanks.
But thanks a lot for your participation at least your interest and articles give me some confidence. 
Naman AgarwalUsing 2phase system will provide you gain of around 1.4 time of 1phase system. Using a 3 phase system will provide you gain of 1.57 times the gain of 1phase system. using the system of 4phase , 5 phase will provide you very little increased gain of 1.6 and 1.62 times gain of 1phase system. So we stick ourseleves to 3 phase system . Hope You got it.

Akhilesh Kumar Nair
If you are talking about control system gain then will you please elaborate that equation and how the gain is related with number of phases and if I am taking all the phases separately than why the no. of phase will play a role in gain.naman2511Using 2phase system will provide you gain of around 1.4 time of 1phase system. Using a 3 phase system will provide you gain of 1.57 times the gain of 1phase system. using the system of 4phase , 5 phase will provide you very little increased gain of 1.6 and 1.62 times gain of 1phase system. So we stick ourseleves to 3 phase system . Hope You got it.
I want to specify again that I am not interested I whole buck of system I am only taking small scale units where the generation is limited to small distance and load or mainly concentrated on generator only.
. 
Naman Agarwali am talking about the power gain...
single phase power is VIcos(phi)
while that of three phase system, power is sqrt(3)*V*I*cos(phi) where V and I are the line voltages and line currents. 
Akhilesh Kumar Nair
Bro that’s way of to represent the power and if I am taking all phases separately each phases and using the power representation as 3V(ph)I(ph).naman2511i am talking about the power gain...
single phase power is VIcos(phi)
while that of three phase system, power is sqrt(3)*V*I*cos(phi) where V and I are the line voltages and line currents.
And the line power will have 2 factors(Which is rut3 in case of 3 phase) in front of V(L)I(L) for different set of lines approximately it will be equal to 5/1.18 and 5/1.90 and these values are still comparatively greater than rut 3 of 3 phase.
But this line factors and power notations are insignificant if I am considering each phases separately as I mentioned in above discussion. 
vamsi kancharlafor 3phase peak voltage can be obtained well when compared with 5 phase

Akhilesh Kumar Nair
If you're explaining something or asking I apologize sir but I don't understand this statement but want highlight following things.vamsi kancharlafor 3phase peak voltage can be obtained well when compared with 5 phase
The timing of peak of each phase is function of frequency.
And yes the peak voltage between phases in 3 phase is 120 and in case of 5 phase will be 72. 
Jeffrey Arulraj
Mate I aam sure you mean that the Phase difference between the maximum voltage is 120 in 3 phase and 72 in 5 phase networksAkhilesh Kumar NairAnd yes the peak voltage between phases in 3 phase is 120 and in case of 5 phase will be 72. 
Akhilesh Kumar Nair
Yes brother I want highlight that because I couldn't conclude any thing from previous statement by Vamsi so I want make concept of peak a little clear so that I can cover anything that he might want to state.Jeffrey SamuelMate I aam sure you mean that the Phase difference between the maximum voltage is 120 in 3 phase and 72 in 5 phase networks 
Saandeep SreerambatlaI have spoke to my friend who has done some Phd in electrical Engineering, I have shown him this thread and asked him why is this?
He told me that,
assume unity PF, then power generated in single phase is VI.
in 2 phase system,
if the Emf is E, and the current is I, then the per phase voltage will be 1/root2 * E.
So the total power generated in this case is , 2 * 1/root2 * E * I
so that is root(2) * EI = 1.414EI.. and as we already know 2 phase has some problems with the phase difference.
next comes 3 phase, in this case it is 1.5 EI.
After that , in higher phases the power will be 1.57EI only, thus it gives only a marginal increment, thus we dont use it. 
Akhilesh Kumar Nair
First of all thanks alot for your this much of concern and time sir but I have following problems in understanding your statement.Saandeep SreerambatlaI have spoke to my friend who has done some Phd in electrical Engineering, I have shown him this thread and asked him why is this?
He told me that,
assume unity PF, then power generated in single phase is VI.
in 2 phase system,
if the Emf is E, and the current is I, then the per phase voltage will be 1/root2 * E.
So the total power generated in this case is , 2 * 1/root2 * E * I
so that is root(2) * EI = 1.414EI.. and as we already know 2 phase has some problems with the phase difference.
next comes 3 phase, in this case it is 1.5 EI.
After that , in higher phases the power will be 1.57EI only, thus it gives only a marginal increment, thus we dont use it.
1. Sir if you are talking about 3 phase line power representation then I think the equation of power is some things rut3 times VI(line to line parameters) and it is somewhat 1.732 but sir you states it 1.5 in the above statement if we're not on the same page then please correct me.
2. But if we are talking about the same equation then sir as I previously stated there will be two different factors(which is root 3 in case of 3 phase) depending upon choice of lines and the values of those two factors are 5/1.18 and 5/1.9
Sir as factor of multiplication depend on the two line you choose for observation but still the lesser value gives is 2.63 time VI which is significantly higher then 1.73 almost 66% more. 
Saandeep SreerambatlaI think you have got me wrong here.
Consider a 3 phase system which has phase angle of 120 degrees and which are in series in this case the per phase voltage will be 1/2 * E.
So, if you calculate the power that can be transmitted with current = I , then it will be 1.5EI.
So this gives the 3 phase 1.5 times the power.. and going by the same theory we get that polyphase doesnt give much of an edge over what 3 phase gives. 
Akhilesh Kumar Nair
Sir I still don't get your point of 1.5VI,clear some of the main points of your statement...Saandeep SreerambatlaI think you have got me wrong here.
Consider a 3 phase system which has phase angle of 120 degrees and which are in series in this case the per phase voltage will be 1/2 * E.
So, if you calculate the power that can be transmitted with current = I , then it will be 1.5EI.
So this gives the 3 phase 1.5 times the power.. and going by the same theory we get that polyphase doesnt give much of an edge over what 3 phase gives.
1. Sir the parameters you taken V &I are line to line parameters or line to earth values.
2.how the per phase values is coming 1/2 V if suppose v is phase voltage than total power will be 3VphIph.
3.and how the values of power is coming 1.5 VI... 
Void RunnerYou can use as many phases as you want. The main concerns are costs and heat generation, at a certain point the gains provided aren't worth the extra risk and investment. That's about it.
BTW Electronics on motherboards and SMPS often internally divide the input into multiple phases, from 3 to 16 depending on the motherboard. An odd number is always preferred because of the neutral wire current problem mentioned earlier in this thread. 
Akhilesh Kumar Nair
I agree with your point brother that practical and economical aspects are also a concern but I am not going to that much level of practical or heavy mass production, what I meant is for small scale (where direct load is connected as discussed before) purpose 5 phase alternator may not have any theoretical limitation and not considering to be part of discussion but as far as I think by increased no of phases we are just reducing electrical loading per phase consecutively heat.Void RunnerYou can use as many phases as you want. The main concerns are costs and heat generation, at a certain point the gains provided aren't worth the extra risk and investment. That's about it.
BTW Electronics on motherboards and SMPS often internally divide the input into multiple phases, from 3 to 16 depending on the motherboard. An odd number is always preferred because of the neutral wire current problem mentioned earlier in this thread.
And bro I am not just talking about increased no of phase but about 5 phase generation not just splitting the single phases by capacitive, inductiveelectronic circuit and yes your point of SMPS might be helpful for to find some sort of its application of 5 phase, thank you for showing interest in this discussion. 
pinank
We know nature always follows a balanced system. Now consider a system with more than 3 phases. The angular displacement between two phases will not be equal. Say we have a 4 phase system, A,B,C,D. Phase difference between Ab, BC, CD, DA is 90 degrees. But what about between AC, or CB, or DB all are different. TAke up 5 phase or any phase system you wont get a balanced one. Now, take a 3 phase system, all the phases are 120degree apart. So we have a balanced system. We now can apply all KVl KCl etc etc theorems. Also, the 3 phases, being balanced, now we can consider them equal, and calculations done for one phase will inherently apply for other 2 phases as well. Hence three phase is always preferred. Hope I have cleared your doubt.Akhilesh Kumar NairI agree with your point brother that practical and economical aspects are also a concern but I am not going to that much level of practical or heavy mass production, what I meant is for small scale (where direct load is connected as discussed before) purpose 5 phase alternator may not have any theoretical limitation and not considering to be part of discussion but as far as I think by increased no of phases we are just reducing electrical loading per phase consecutively heat.
And bro I am not just talking about increased no of phase but about 5 phase generation not just splitting the single phases by capacitive, inductiveelectronic circuit and yes your point of SMPS might be helpful for to find some sort of its application of 5 phase, thank you for showing interest in this discussion. 
Akhilesh Kumar Nair
Brother why don't you just think for the 5phase phase angle division it's 72(balanced) all the odd phased system will be balanced and I am thinking for increase in just one more iteration for small scale standalone purpose.....most of the rest is discussed before.......by the way thank you for showing interest in this discussion.pinankWe know nature always follows a balanced system. Now consider a system with more than 3 phases. The angular displacement between two phases will not be equal. Say we have a 4 phase system, A,B,C,D. Phase difference between Ab, BC, CD, DA is 90 degrees. But what about between AC, or CB, or DB all are different. TAke up 5 phase or any phase system you wont get a balanced one. Now, take a 3 phase system, all the phases are 120degree apart. So we have a balanced system. We now can apply all KVl KCl etc etc theorems. Also, the 3 phases, being balanced, now we can consider them equal, and calculations done for one phase will inherently apply for other 2 phases as well. Hence three phase is always preferred. Hope I have cleared your doubt. 
pinank
No in a 5 phase system you won't get the symmetry between the phases. Let's say there are 5 phases A,B C D E. Now the angle between the phase A and C/d/e won't be 72 degrees. So how can u consider this as a balanced system. So again if suppose we calculate the capacitance or inductance of a line, for a 3 phase system, the mutual inductance and capacitance cancel out. But for a 5 phase it won't. And because the symmetry is not maintained in 5 phase the calculations become cumbersome. Hence no 5 phase system. Hope I am a lot more clear and convincing this time! 😛Akhilesh Kumar NairBrother why don't you just think for the 5phase phase angle division it's 72(balanced) all the odd phased system will be balanced and I am thinking for increase in just one more iteration for small scale standalone purpose.....most of the rest is discussed before.......by the way thank you for showing interest in this discussion. 
Akhilesh Kumar Nair
Brother I don’t know how you define balanced system although I was discussing about standalone system which doesn’t require complex power system calculations…… but I want put some pointspinankNo in a 5 phase system you won't get the symmetry between the phases. Let's say there are 5 phases A,B C D E. Now the angle between the phase A and C/d/e won't be 72 degrees. So how can u consider this as a balanced system. So again if suppose we calculate the capacitance or inductance of a line, for a 3 phase system, the mutual inductance and capacitance cancel out. But for a 5 phase it won't. And because the symmetry is not maintained in 5 phase the calculations become cumbersome. Hence no 5 phase system. Hope I am a lot more clear and convincing this time! 😛
The balancing of the system is not defined by the angular difference as you are saying, yes in present theme of 3 phase system the balanced system is defined by phase difference of 120 degree.
But basically balanced system is defined by the (function of load) current in each phase related by their phase angle in 5 phase system those attributes will be fixed by calculations based on two angles I think it is a big portion that is mentioned earlier .
But for your clarification please see the pictures you may understand me……. 
pinank
Yes you can say it in a way. But if u are wondering why a 5 phase system is not used in generators, the main reason being the economic viability which is but of course. The other is the amount of computations required for such system.Akhilesh Kumar NairBrother I don’t know how you define balanced system although I was discussing about standalone system which doesn’t require complex power system calculations…… but I want put some points
The balancing of the system is not defined by the angular difference as you are saying, yes in present theme of 3 phase system the balanced system is defined by phase difference of 120 degree.
But basically balanced system is defined by the (function of load) current in each phase related by their phase angle in 5 phase system those attributes will be fixed by calculations based on two angles I think it is a big portion that is mentioned earlier .
But for your clarification please see the pictures you may understand me……. 
Akhilesh Kumar Nair
Yes that is the first thing that strikes anyone’s mind regarding this topic but somehow I tried to make some circumstances and assumptions likepinankYes you can say it in a way. But if u are wondering why a 5 phase system is not used in generators, the main reason being the economic viability which is but of course. The other is the amount of computations required for such system.
1. Taking smallest electrical system even diesel engines of traction not even standalone systems for limiting economic and computational crises.
2. Considering calculation and computation limits as technocrats we know how complex the load flow system which is handled by SCDA like nothing and rocket trajectory and aerodynamic handled by computers like toys for scientist.
3. And this 5 phase system will just increase in one more set of calculations (for smaller scale mentioned in point 1) that are still based on conventional methods which were introduced by Tesla when Edison’s DC supply ruled Electrical word and 3 phase power system calculations were headache at that time and now they are solved by Graduates.
I am not taunting or showcasing but this points can be considered to forget about those aspects and focus on the technical limitation of 5 phase and I am sure there are some technical limitations otherwise at least this topic could be googled out.
And once again thanks for participating in discussion. 
Akhilesh Kumar Nair
Yes that is the first thing that strikes anyone’s mind regarding this topic but somehow I tried to make some circumstances and assumptions likepinankYes you can say it in a way. But if u are wondering why a 5 phase system is not used in generators, the main reason being the economic viability which is but of course. The other is the amount of computations required for such system.
1. Taking smallest electrical system like diesel engines of traction not even standalone systems for limiting economic and computational crises.
2. Considering calculation and computation limits as technocrats we know how complex the load flow system which is handled by SCDA like nothing and rocket trajectory and aerodynamic handled by computers like toys for scientist.
3. And this 5 phase system will just increase in one more set of calculations (for smaller scale mentioned in point 1) that are still based on conventional methods which were introduced by Tesla when Edison’s DC supply ruled Electrical word and 3 phase power system calculations were headache at that time and now they are solved by Graduates.
I am not taunting or showcasing but this points can be considered to forget about those aspects and focus on the technical limitation of 5 phase and I am sure there are some technical limitations otherwise at least this topic could be googled out.
And once again thanks for participating in discussion. 
jvkoladiaAs we increase number of phases, power output also increase.....so it is good thing. But by increasing number of phases,complexity of circuits also increase because we need more number of connecting leads(wires), switches etc. Also, voltage unbalance in 3 phase system is less than 5 phase or any more than 3 phase system. So 3 phase system is economical and nowaday it is more populer.

Shihabeldin MohyeldinWhen there's 120° between phases the sum of the voltages at any time will be zero.
This means that with a balanced load no current flows in the return line (neutral).
Also, if each phase is 230V with respect to the neutral (star operation), then there will be 230V *√3 = 400V between any two phases (triangle or delta operation), and they're also equally spaced, i.e. at 120° angles.
Equally spaced is the evident way to keep it mechanically balanced, but you also need it that way to have the voltages equal, so that the net current is zero in a balanced load.
Thanks 
Shihabeldin MohyeldinThis is certainly why the threephase system as it is currently designed is nice. I think the original reason behind why it is as it is is that it's easiest to wind a motor with the output phases equally spaced.
You are reading an archived discussion.
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