Defnition of Ground..

Hi,

Can any one give a proper definition for GROUND(Gnd) in a circuit.....?

Quote from Wiki:

In electrical engineering, ground or earth may be the reference point in an electrical circuit from which other voltages are measured, or a common return path for electric current, or a direct physical connection to the Earth.

Click to expand...

All about Ground (GND):

Ground (electricity)

Hope the link helps.

In electronics ground means a reference point of a circuit from which all voltages are measured.
In electrical ground means ,it is connected to ground to draw the extra current from the short circuit ,leakage current etc .

demetal said:

Can any one give a proper definition for GROUND(Gnd) in a circuit.....?

Click to expand...

This should help Untitled Document

thannara123 said:

In electronics ground means a reference point of a circuit from which all voltages are measured.

Click to expand...

Correction: It sometimes means that. The fact is that many, perhaps most, people use the word without thinking (or understanding) what it does mean.

In electrical ground means ,it is connected to ground to draw the extra current from the short circuit ,leakage current etc

Click to expand...

Astonishing.

How, exactly, does "ground" draw the extra current from anything?

I really want to know.

in according to my practical kowledge in electronics .,in dual power supply the midpoint is ground.The power supply where have only positive and negative lead .in which negative lead consider as ground (check out circuits you can find) . In electrical ground drawing extra current means the leakage current (for example a leakage from iorn box) follow to the earth tgrouh the ground wire .

A "ground" in electric or electronic circuits, is a theoretical entity that is at zero volts everywhere. The Earth itself is often used as an approximation to this, and sometimes grounds are called "Earth" connections. There is only one ideal ground.

However, in electric and electronic engineering, much of the challenge is dealing with real-world things that differ from the ideal or theoretical model. Grounding is one of those where the difference between the ideal and real-world must be addressed. The topic of grounding and shielding is complex.

Engineers take complete courses in grounding and shielding and very senior engineers can puzzle over grounding issues for days or weeks, so it is not possible to give a comprehensive answer in a short space.

It is useful to think of some of the different functions of a ground:
1. A ground provides a return path for current
2. A ground provides a reference point for measuring other potentials or signals
3. A ground provides a safety connection for metal enclosures
4. A ground provides a shield to screen out electromagnetic noise, as in a coaxial cable or Faraday cage
5. A ground plane is needed for an antenna to function properly
6. In electronic circuits, the ground is often used as a heat sink to dissipate heat from components

It is often a good idea to use different "grounds" for different functions. For example in electrical wiring both the neutral and protective ground wires are ground connections, but one serves as a current return path and the other is a safety connection. There are very good practical reasons to have these implemented as two different wires.

In electronic circuits, different grounds are often used because real ground paths have resistance, inductance and capacitance and signals take time to travel from one part of the circuit to another--especially when thin copper traces are used on a circuit board.

The primary concern in real-world grounding is considering current flow and current paths. For example in a PC board, power returns and high-speed clock signals usually use different copper ground traces than low-level audio or sensor signal reference grounds, so that the transient current from switching does not affect the ground reference for tiny signals. The grounds are tied together at one point, so that there is no circuit path for current to travel between the paths, but they are at the same potential voltage.

None of this would be necessary if we had an ideal ground--zero volts everywhere, with no impedance between any two points.

Syncopator said:

...How, exactly, does "ground" draw the extra current from anything?...

Click to expand...

The Ground in sense of Earth, drains extra electric charges by equalizing voltage between 2 bodyes ( Earth and equipment ).
We must consider the Earth ( in planet concept ) like a body with comparativelly infinite electric capacity, virtually able to drain all exceded charge from equipment, trying to redistribute its electrons equally.

+++

ground is a point ,to which, conventional current flows or

Ground is a reference point from which all the voltages are measured.

Quote from Analog Devices Linear Design Seminar:

Ground is NOT a place where "good signals" go when they die...... In real life, ground conductors have both resistance and inductance and may also be carrying unpredictable currents which will give rise to voltage drops when they flow in the ground impedances...... Ground is a "dirty world". All voltages are differential.

Click to expand...

andre_teprom said:

The Ground in sense of Earth, drains extra electric charges by equalizing voltage between 2 bodyes ( Earth and equipment ).
We must consider the Earth ( in planet concept ) like a body with comparativelly infinite electric capacity, virtually able to drain all exceded charge from equipment, trying to redistribute its electrons equally.

+++

Click to expand...

You are as confused as most other people are.

---------- Post added 01-06-11 at 00:04 ---------- Previous post was 31-05-11 at 23:36 ----------

=ckshivaram;905777]A "ground" in electric or electronic circuits, is a theoretical entity that is at zero volts everywhere. The Earth itself is often used as an approximation to this, and sometimes grounds are called "Earth" connections. There is only one ideal ground.
Waffle.

Click to expand...

However, in electric and electronic engineering, much of the challenge is dealing with real-world things that differ from the ideal or theoretical model. Grounding is one of those where the difference between the ideal and real-world must be addressed. The topic of grounding and shielding is complex.

Engineers take complete courses in grounding and shielding and very senior engineers can puzzle over grounding issues for days or weeks, so it is not possible to give a comprehensive answer in a short space.[/QUOTE]
Waffle.

It is useful to think of some of the different functions of a ground:
1. A ground provides a return path for current

Click to expand...

So does the negative pole of any source. "Ground has nothing to do with it.

3. A ground provides a safety connection for metal enclosures

Click to expand...

When, and only when, the "ground"is Earth.

4. A ground provides a shield to screen out electromagnetic noise, as in a coaxial cable or Faraday cage

Click to expand...

It is not necessary for such screens to be connected to Earth, or whatever it is you call "ground".

5. A ground plane is needed for an antenna to function properly

Click to expand...

No. Mobile antennas, i.e. those mounted on a vehicle usually, but not always, do. Frame, or loop, antennas do not. Yagi antennas do not. Quad, or cubical quad antennas do not. Many broadcast antennas are constructed on the Earth's surface and need no "ground plane".

6. In electronic circuits, the ground is often used as a heat sink to dissipate heat from components

Click to expand...

No. A thermal mass is used as a heat sink. Earth, or "ground", has nothing to do with it

It is often a good idea to use different "grounds" for different functions. For example in electrical wiring both the neutral and protective ground wires are ground connections, but one serves as a current return path and the other is a safety connection. There are very good practical reasons to have these implemented as two different wires.

Click to expand...

This does nothing to explain what Earth and/or "gound" is.

In electronic circuits, different grounds are often used because real ground paths have resistance, inductance and capacitance and signals take time to travel from one part of the circuit to another--especially when thin copper traces are used on a circuit board.

Click to expand...

What do you consider to be "real gound" and what is something you presumably consider to be "artifical ground"?

The primary concern in real-world grounding is considering current flow and current paths. For example in a PC board, power returns and high-speed clock signals usually use different copper ground traces than low-level audio or sensor signal reference grounds, so that the transient current from switching does not affect the ground reference for tiny signals. The grounds are tied together at one point, so that there is no circuit path for current to travel between the paths, but they are at the same potential voltage.
None of this would be necessary if we had an ideal ground--zero volts everywhere, with no impedance between any two points.

Click to expand...

This does nothing to explain what Earth and/or "ground" is.

so is there any reasonable definition for ground.....?

Hi Syncopator,

you raised a question to every point written by almost everyone, but did not give your answer to it... what does this infer????

demetal said:

so is there any reasonable definition for ground.....?

Click to expand...

ckshivaram said:

Hi Syncopator,

you raised a question to every point written by almost everyone, but did not give your answer to it... what does this infer????

Click to expand...

Yes, demetal, there is a reasonable definition of "ground"; two actually. Did you read my short article about Earth/ground in the link which I provided in my first post in this thread? I shall give it again at the end of this one.

ckshivaram, infer? I think the word you were looking for is imply.

The implication is that many, many, people use the word "ground" without thinking, and without understanding it.

Part of the problem is that people are no longer taught properly, and people no longer learn properly. They often simply copy others who are in the same position; they may be in the classroom, they may be authors of books and they may be people who answer questions on forums such as this one. Truly a case of the blind leading the blind.

I well remember one of my instructors in college deliberating at some length about "Earth". I shall forever be thankful that he did.

Another part of th problem is that once somebody gets a notion in their head it is difficult, sometimes impossible, to change that notion. They will argue that black is white simply to win arguments.


Ok, reasonable definitions.

It started with Earth. Which, in an electrical/electronic environment, is a connection to the planet on which we live. There's no need here to empphasise that it should be a low impedance connection etc, etc.

Like many other words in the English language, particularly in the sciences, it has become misused and largely misunderstood.

The Americans are responsible for much of this (sorry, any Americans who read this, I'm simply stating facts).

Somebody, somewhere, thought it clever to say "ground" instead of earth.

At one time the two words were synonymous.

In the early days of radio, a connection to the Earth was essential for antenna efficiency. Later, as radio receivers became mains powered, a connection to Earth was necessary for reasons of safety - another area which many people really do not understand.

It was convenient, in the construction of radio receivers to have the negative side of the supply connected to the receiver's chassis, which was connected to earth. I have no idea why the negative pole was selected, it could equally well have been the positive. [In signal analysis, all supply rails, be they positive, negative or zero volts, are considered to be connected together (shorted if you Like).]

So, if anyone said "earth" or "ground" it was understood that it was a connection between the planet and the equipment, and that it was usually to the equipment's chassis, which also usually served as the common negative rail.

With the advent of dry batteries and portable receivers we all know what happened, don't we?

Old habits dying hard etc. The common connection, still a chassis in the early portables, was still referred to as "ground".



We now have two conditions where the word "ground" can be properly used.

1. A connection to the Earth, which usually will be connected to an equipment's chassis etc, which demands that it is qualified by saying "earth ground".

2. A connection to a system's common signal and or supply point which is not connected to earth, which demands that it is qualified by saying something like "chassis ground".



In the vast majority of cases we see simply "ground", which does not convey the full picture.

Saying "ground", without qualification, is sloppy and inaccurate.


What do you make of a battery operated circuit, that of a flashlight for example, say a single cell a bulb and a switch. You have seen circuits like that, I'm sure, where the negative pole of the cell is called "ground". Why?

The answer is habit and ignorance.


Earth, or ground, isn't an electrical sponge or bottomless pit into which we can pour unwanted electrons/current. Not does it magically "attract" current.
For current to flow in the Earth, it has to be part of a circuit.

My short article may be read at www.davidbridgen.com/earth.htm

sorry but your post shows your arrogance and wrong attitude towards others.... please keep the language straight .... no one here is to give wrong information or to prove that they are genious...

thats what you are trying to tell here... and No one is 100% perfect you need to remember that... no authors and people are not mad or without knowledge to write wrong data...

Yes it can be a case of misunderstanding by different people.... but its high time you please keep the attitude down to earth....

there are people who take objection to your writing as not all you said is true.... in your case we are all blind people only... thanks for telling that..........

ckshivaram said:

... not all you said is true....

Click to expand...

Kindly elaborate.

Syncopator,


I have some objections regarding your previous explanations.
However, due you divert the subject to a personal course, I´ll keep my opinion and must to ignore your discord about my post.
( note that you neither elaborated it and didn´t explained your reason to disagree )

I hope my single contribution had been relevant to aid demetal.

+++

andre_teprom said:

Syncopator, I have some objections regarding your previous explanations.

Click to expand...

Ok. If you don't explain what they are, I can't address them.

However, ... you divert the subject to a personal course ...

Click to expand...

No diversion took place. I have simply responded to erroneous statements and misconceptions.

... you neither elaborated it and didn´t explained your reason to disagree ...

Click to expand...

I have written sufficient explanation regarding what "ground" is, and what it isn't.

I hope my single contribution had been relevant to aid demetal.

Click to expand...

We can all live in hope.