SINGLE PHASE AND 3 PHASE

The difference between 1 and 3? Are you serious?

You need more school time my friend... I suggest a generalized course in critical thinking.

Single phase uses 2 wires to connect plus a ground, 3 phase uses 3 wires and a ground. With single phase you only have one wave of 60 cycles. With 3 phase you have three waves 120 degrees apart giving more power transmitted to the armature. Good luck in your education.

Well, of course, us in the civilized world only cycle at 50Hz.

Supprised that Del the Cat hasn't jumped on this guy for a bit of arm wrestling!

Dear friend

Please do not forget that the world is not restricted to 50 Hz and that much more people than in 50Hz use 60Hz.

Sincerely yours

A 60Hz user

Nils desperundum carborundum!!!!

http://en.wikipedia.org/wiki/Polyphase_system

You may have many side view to distinguish the single phase from the three phase system. Here a few of them in English :)

(1P) denotes single phase and (3P) for tree phases

A. Line used

(1P) Two lines : one for ground and other for live (don't touch, it can kill you!)

(3P) Four lines in Y (wye) system : one for ground and three for live. You may consider it as three set of single phase with ground line in common (held together). Meanwhile each live lines have 120 degrees of phase difference. For instance if one being 10^o then the others will be 130^o and 250^o (which again 120^o differ from 370^o = 10^o)

(3P) Three lines in Δ (delta) system : no ground and power produced from each pair from the three lines. Let the lines as a, b, and c. We have three pairs : a-b, a-c, and b-c. The fact that each line differ 120^o from relatives, gives amplitude of voltage difference in each pair as high as √3 times of live-ground pair voltage difference amplitude with the same frequency.

B. Line Efficiency to transmit 3 pairs of point contact

(1P) minimum 3+1 lines required

(3P) minimum 3 lines required

Keep going to find other interesting difference!

First: All generation is in 3 phase, simple as that.

The question is how many poles in the generator is most efficient?

Single phase is simply connection between 1 phase and ground or 1 phase and another phase.

Most generation is 3-phase. Go to any big-box home improvement store or your local garden/farm center, and I'll bet most of that generation is single phase.

Other things your are going to find out but consider also that:

1)Optimizing cables concerning to height, etc. is more easily achievable in three phase circuits.

2)Load balance among phases is possible in three phased circuits.

3)More energy is transmissable in three phased circuits.

Some simple calculation your electric circuit teacher is going to show you will show these points.

Good luck in your studying process!

Saulo

How long have you been studying for you to find out that you do not understand the differences? They are pretty fundamental.......

Most people here have given you good answers, has it helped?

Most of the building equipments require only single phase 240 V The 3 Phase is most effective and econimic way of transmitting power when compared to single phase .

3 phase means 3 seprate 240 V supplies. To keep it simple consider the example.

1. I have a magnetic field rotating over a

a. single current carrrying coil

b . 3 current carrying coil

1. In the first case one end of the coill becomes alternatively postively and negatively charged with respect to another end and is termed as Live .

The other end is at zero voltage and is termed as neutral. This is what happened in single phase supply.

2. When we conside the second case we have 3 colis producing alternative positive and negative voltages and 3 coils producing Zero Voltage or Neutral.

The first 3 coils forms the Live wires and the other 3 coils can be grouped together and formed a common neutral.

The advantage of 3 phase supply is

it requires only 4 wires rather than 3 x 2 = 6 wires as in single phase .

When the load is balanced all the current is carried by phase conductors and the neutral has no role ,so in that case we can have only 3 conductors thus making it more better.

Dear dhilju82,

you have some quaint ideas about 3 phase power, in with some reasonable ones.....!

If you used the spelling corrector, you would not over see such errors as "colis" for coils.

You have maybe not had the chance to study electrical theory, or you would not have made the mistake of saying:-

"When the load is balanced all the current is carried by phase conductors and the neutral has no role"

This is so far fetched, I almost think that you meant it as a joke, did you?

If the answer is no, you need to get out the text books and learn basic electrical theory!!!!! You seem to forget that any circuit needs a return path!

In the case of using 3 phase as a deliverer of 240 volts, this is the neutrals job. Voltage between phase & Neutral nominally 240 volts in Europe....50 Hz.

No neutral = No electron Flow = no current flow!!! The neutral has a very important role in single phase working!!!!!

In the case of a lot of 3 Phase motors (or transformers), they actually do not need a neutral to work. Sometimes it is connected to the motor box as a place to put the cable only, but is not used internally in the motor.

It can also be connected (I have been informed, no personal experience why) I am told on some special motors(?). I have no idea why, but usually a CR4 member knows!!!

The neutral point on on a 3 phase motor is (not to be confused with neutral power!) is sometimes brought out to an unused connector, to allow better fault finding when earthing problems happen I am informed, though I have not seen this personally...the 3 fields are usually made as a unit, but if they were separable, then having the neutral point would be very important!

A useful link at Wikipedia is:-

http://en.wikipedia.org/wiki/Three-phase_electric_power

If you have any further questions, ask and we will try and help you out.

Hi

I didnt present it properly . what I meant was under balanced load conditions, the currents of 3 phases are identical and their sum equals to zero. In other words a flow in one path returns in other 2 paths which act as a neutral in this case . So a requiremnt of 4th conductor as a neutral is absent in such balanced systems making it better optimisation of conductors than unbalanced systems.

Still wrong!!!

If you want to have 240 volts from a 3 phase supply in Europe for example, you MUST connect each 240 system between 1 phase and the neutral........NOTHING ELSE WILL WORK. Balancing is nice for the transformer, but does not remove the need for a neutral!!!

The neutral wire is always needed, except where you have a 3 phase 380V motor or transformer connected to ALL 3 PHASES!!!!

What you are saying is completely and utterly wrong and dangerous for other readers who might believe what you are saying!!!!

Draw yourself a diagram and connect a 3 x hair dryers to a 3 phase supply without using neutral........try it out! Remember phase to phase is 380 volts nominally.....!! A hairdryer will just evaporate!!

Only in the USA where phase to neutral is 115V approximately, can you go from phase to phase and get around 230volts without using neutral!!!!! That is NOT what you keep stating wrongly!!

Please please get some books on this and start studying, otherwise you might kill somebody and the somebody might be you!!! If your education is lacking in this area, it is probably lacking in a lot more other areas too.

Sorry to be so negative, but what we are wrongly talking about is lethal stuff!!

I agree with you entirely Andy, and you do not get any second chances with 3 phase current, unless you are very fortunate.

IF YOU DON"T KNOW WATT FROM WHAT........LEAVE IT ALONE.

Mobi,

brilliantly put. Thanks for your knowledge and support, I hope he listens to us.....we still do not want to lose him to a stray watt or two.......What, What!!!

Sadly for him, he has exposed an alarming hole in his basic knowledge of electricity....but a few hours study should fix it....

There are three things we all need to be careful of:-

AC

DC

JC

Or if you are not careful of AC or DC you then meet JC? (or your own God?)

I like that one.

Hope there aren't too many who don't know what from watt.

....and it appears to be switched on!!!

fearful!!

Nah.........the switch is probably upside down!!!

Would you just touch all pins and confirm that please?

What!!!! And end up like this.

My God, that alone is a potent reason for the original poster to start studying his subject better.......I have never seen anything more gruesome....

Poor me to understand you not!

What do you mean with JC?

I have no idea at all, no such jargon in my country!

As you are a guest who has not identified yourself in any way to us, or your religion, country of origin etc. I am afraid you will have to get used to not being "involved" or catered for so to say.......

Substitute "Maker" for JC, perhaps this may be better for you....as most of the members of CR4 are in some way Christian. Did that help?

Though Christianity is certainly not a requirement, as we are happy with all races and religions and points of view.....but some things may not be so quickly apparent to you because of that!!

But still many many posters come from India and surrounding areas, far east, everywhere in fact!!

Or even better, join CR4 with full details and your very own "Nom de Plume"....

Well said Andy. If I had made a statement concerning that remark by Guest, it may not have been quite so tactfully said. Thank you for that.

I had already taken the Pills on that day......it was easier for me to be helpful for once!!

Don't get me riled before them though!!!

I don't know Andy, I take my pills and I still get nasty. I don't even have to try.

I think you had better tell me what they are.

I agree with you.

Domestic consumption, we need a phase and a neutral otherwise some one is gonna be killed or damage to equipments. Also Domestic consumption lines to an estate for example should be balanced or else there will be a voltage imbalance.

For industrial consumption or large consumers we need 3phases and a neutral to support other equips like lihgting and domestic socket outlets.

The grounded point neutral for star or delta connection with respect to phase are single phase. Between phase to phase for the same are at 120 degree electrical phase differance are as 3 phase. The relation between phase to phase and phase to grounde dneutral value are square route of 3 i.e nearly 1.73

nascon

Your statement:-The grounded point neutral for star or delta connection

is missleading I feel, in a delta connection there is no neutral point.....

The one corner of delta being grounded.

depicts the 3-Wire, Three-Phase Delta Scheme ungrounded Delta, normally confined to protected environments such as fully enclosed ducts or overhead transmission lines that cannot b e r e a c h e d w i t h o u t extraordinary means. Each conductor's ground voltage is equal to the full phase voltage of the system. ground point affixed to one corner of the Delta, which effectively lowers one phase's voltage reference to ground to zero, but retains a phase-to- phase voltage potential. The corner-grounded phase acts in much the same way as the grounded neutral of the single- phase Edison system, carrying current and maintaining ground potential.

Can you tell me where and why this is done? What are the practical reasons????

I wish to learn more as it just sounds dangerous to me at this point!!!