Does Single Phase Or Three Phase Require a Neutral?

[MattyH]

Also, how does the neutral work on a phase system?

 

[Plonker 3]

I know, maybe we should do something more pro active to make it happen ourselves then?

 

[MattyH]

Still though. People shouldn't be so rude. Seeing that some of the guys who said the abuse are admins aswell? It's really embarrassing for the forum.

 

[Plonker 3]

Unfortunately some folk don't always look at who has posted the question. Please don't let it put you off the forum as it is a good place to learn from and there are some very knowledgeable folk on here who will be more then happy to help you.

I am sure I have made similar comments in the past, I am ashamed to say. But would like to think I know better know.

 

[snowhead]

I'm on my second year at college studying electrics. It's very rude for you guys to say that.

Wait till you get onto a site, there will be more of the same to come.

 

[MattyH]

Wait till you get onto a site, there will be more of the same to come.

I know

 

[Inteificio]

Personally I don't think there is anything wrong with a bit of "£$% taking, it is all part of being a spark.

The way I explain it to most apprentices is as follows.

You need a way for the electricity to get to the load, and to get back. All the switches and fuses need to be in the live. The live is the wire that feeds the load, the wire that comes back is the neutral.
For three phase the electricity can enter or exit through any of the 3 lives. However if the load is unbalanced you also need a neutral to even things up.
There is an equation for calculating neutral currents on a 3 phase load, but you don't need to know it.

Hope that helps,

 

[mickys86]

Personally I don't think there is anything wrong with a bit of "£$% taking, it is all part of being a spark.

The way I explain it to most apprentices is as follows.

You need a way for the electricity to get to the load, and to get back. All the switches and fuses need to be in the live. The live is the wire that feeds the load, the wire that comes back is the neutral.
For three phase the electricity can enter or exit through any of the 3 lives. However if the load is unbalanced you also need a neutral to even things up.
There is an equation for calculating neutral currents on a 3 phase load, but you don't need to know it.

Hope that helps,

Might need to know it to pass ya exams.....

 

[Inteificio]

Which exams do you get asked it in?

I lack a 2391, but have looked through the past papers and not seen it asked.

 

[mickys86]

Which exams do you get asked it in?

I lack a 2391, but have looked through the past papers and not seen it asked.

I did say might..... I'm not going to lie. I am very inexperienced in three phase calculations. I have just passed my level three and I guess these things come with time, experience and dedication to the job.

 

[mickys86]

Taken from the Swindon massive revision site.....

 

[Inteificio]

So are you going to to provide a question that requires knowledge of the formula, or just one that looks like it does?

I gave the info above to answer this, you don't need the formula.

 

[DPG]

D, since balanced load ? Daz

 

[mickys86]

D, since balanced load ? Daz

Well done daz

And not causing an argument mate. Just saying.

 

[DPG]

Misleading wording in the question I reckon aswell - it says 'calculate' the neutral current, which you can't really do. Daz

 

[Inteificio]

Well you can calculate the current, but you should know that the answer will be 0.

As it seems to have caused to much contention here is the formula.

SQRT I²A + I²B + I²C - (IA x IB) - (IB x IC) - (IC x IA)