Purpose of the neutral

[ggunn]

But Tom described it as having (+) at each end and (-) at the center tap. You can connect two identical DC sources in this way, but instead of 2x voltage from (+) to (+) you get no voltage, but voltage to (-) remains the same. Connect the two (+) terminals together and your sources are in parallel.

Yes, I saw what he wrote, but the DC system he described doesn't make sense unless one hot wire is positive, one hot wire is negative, and the neutral is in the middle. If both hots were positive, then the "neutral" would carry the sum of the return currents rather than the difference. I think he misstyped the polarity of the second hot wire.

 

[kwired]

:jawdrop: even though a wire is concidered to not be a non-current carring conductor. Never get between a neutral(or break) you could be the return path to ground:slaphead:

There is no return path to ground, the return path may go through ground, but it is the source the current is trying to return to. Anything conductive that is in the path becomes part of the current path. If your touching something means you are of lower resistance than other paths then you are a primary conductor of the path and you will feel it.

A neutral is not a non current carrying conductor.

A neutral carrying only unbalanced circuit current in multiwire branch circuits it deemed non current carrying only for the application of ampacity adjustment factors, it still carries current when performing its function in the circuit.

 

[Flux]

Hey kwired I want to hear about this center tap DC circuit you speak of in all the classes I went through in the IBEW apprenticeship never heard of that one what kind of source?

 

[eHunter]

With all due respect, the neutral in a circuit is a current carrying conductor.
From NFPA 70 or NEC Article 100:
Neutral Conductor. The conductor connected to the neutral
point of a system that is intended to carry current under
normal conditions.

The purpose of the neutral conductor is to complete the circuit.
This allows current(electrons) to flow in the conductor from the end of the source windings(X1 or X2) through the load, through the neutral conductor to the neutral connection (X0) which is usually the center tap completing the circuit.

The neutral is not "ground", but it usually is bonded at a single point to the grounding system for safety in clearing unwanted line faults.
The neutral is usually assigned to the common connection point of a electrical power source transformer's windings(X0).
A neutral conductor is not required or used in line to line circuits. In the US some such circuits are 240V single phase, 208V or 480V 3 phase circuits.

The neutral conductors in a raceway are not counted as current carrying conductors because the phase current has already been accounted for in the ungrounded conductors.

There are no DC (direct current) transformers because of the laws of physics. To inductively produce current in a transformer secondary the current in the primary has to alternate voltage polarity and current direction, DC does not aternate polarity or current direction.

Polarity references can be assigned during an instantaneous snapshot of a voltage state of a alternating current transformer's windings.
See the attached pdf ... pictures are sometimes worth thousands of words.
View attachment 8256

 

[Smart $]

...
See the attached pdf ... pictures are sometimes worth thousands of words.
View attachment 8256

Your link don't work for me. I get a Code Forum Message: Invalid Attachment specified. If you followed a valid link, please notify the administrator

 

[eHunter]

Your link don't work for me. I get a Code Forum Message: Invalid Attachment specified. If you followed a valid link, please notify the administrator

I already notified the Administrator. We are experiencing storms wher I am and I lost internet accewss for a few minutes and the edit timed out.

Here is a second attempt... View attachment Transformer_Neutrals.pdf

 

[kwired]

Hey kwired I want to hear about this center tap DC circuit you speak of in all the classes I went through in the IBEW apprenticeship never heard of that one what kind of source?

Put two batteries in series, connect leads to each end, as well as to the point between the two batteries and you have a 3 wire DC source. It is similar in many ways to a single phase winding with a mid point tap.

 

[Goroon]

Long story short ?

Long story short ?

Occam's razor.. :?
The Neutral is there to carry "Intended / Unballanced Current.
The ground is the safety wire for those parts NOT intended to carry current..

 

[kwired]

Occam's razor.. :?
The Neutral is there to carry "Intended / Unballanced Current.
The ground is the safety wire for those parts NOT intended to carry current..

Correct, and they both tie together at some point. If that connection or any point ahead of that connection goes bad, then you have voltage and current from the neutral imposed on the grounding conductor, which is exactly what causes what many call "stray voltage".

 

[Flux]

So this allows you to achieve both voltages IE 12 volt and 24 volt, thanks never thought of DC that way makes sense.

 

[kwired]

So this allows you to achieve both voltages IE 12 volt and 24 volt, thanks never thought of DC that way makes sense.

Put even more batteries in series and you have even more "voltage taps" within your source.

 

[macmikeman]

A quote from my friend Hax

" A neutral is something that you connect when and where you are supposed to in order to make electrical stuff work so you can get paid and go on to the next job."



This would have served the op best if it was on page 1 instead of page 8 or 9..

 

[Flux]

That is true if you have an engineer and a set of funny papers but if say you are installing a new transformer or servicing a MWBC then you might want to know a bit more.:happyyes: As a mechanical engineer with his train parked out front I would imagine he probably just needs to know that a neutral is required to arrive at a required voltage.

 

[robwire]

A quote from my friend Hax

" A neutral is something that you connect when and where you are supposed to in order to make electrical stuff work so you can get paid and go on to the next job."



This would have served the op best if it was on page 1 instead of page 8 or 9..

Or even better yet go hire an electrical engineer and leave it to someone qualified, I didn't know this was a DIY forum. This guy knows just enough to be really dangerous . It's bad enough when guys mess with 120 volts and have no clue.

 

[Flux]

That is why we have to either pull a neutral GC wire per phase or use breaker ties now on MWBC per the NEC:happysad:

 

[ggunn]

There are no DC (direct current) transformers because of the laws of physics. To inductively produce current in a transformer secondary the current in the primary has to alternate voltage polarity and current direction, DC does not alternate polarity or current direction.

Of course. I don't believe anyone said otherwise.

 

[GoldDigger]

There are no DC (direct current) transformers because of the laws of physics. To inductively produce current in a transformer secondary the current in the primary has to alternate voltage polarity and current direction, DC does not aternate polarity or current direction.

With exaggerated respect for the laws of physics, I have to point out that you can indeed make a DC current transformer (CT) by using a superconducting secondary winding. But you can't put any kind of load on it.
The reason that a standard transformer does not work for DC is that the unavoidable losses on the secondary side cause the initial response to any change in primary DC to decay.The magnetic field induced in the coil or core by the primary current remains just the same.

 

[eHunter]

Of course. I don't believe anyone said otherwise.

I don't believe I indicated anyone did.
The statement was an informational reference.

 

[eHunter]

With exaggerated respect for the laws of physics, I have to point out that you can indeed make a DC current transformer (CT) by using a superconducting secondary winding. But you can't put any kind of load on it.
The reason that a standard transformer does not work for DC is that the unavoidable losses on the secondary side cause the initial response to any change in primary DC to decay.The magnetic field induced in the coil or core by the primary current remains just the same.

Is that another DARPA lab experiment?
I have always heard that with enough of someone elses money, time and effort just about anything impractical can be done.

 

[GoldDigger]

Is that another DARPA lab experiment?
I have always heard that with enough of someone elses money, time and effort just about anything impractical can be done.

Actually, I once worked in a research lab that was looking for a practical room-temperature superconductor. As a joke the grad students wrote up a fake grant application for funds to cool a room to .1 degrees K. The summary was, that if you could not increase the temperature of the superconductor, you would just have to reduce the temperature of the room. Fortunately everybody who looked at it got the joke. Otherwise there might be a really cold room out there somewhere right now.

More seriously, superconducting wires do have practical application in DC power transmission. At reasonable cost.