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Grounded Neutral vs. Floating Neutral

02/09/2009 6:03 AM

What is the difference between a grounded and floating neutral in a power system.

What is the effect with regards to load of a grounded and floating neutral.

Please advise. Thanks

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#1

Re: Neutral

02/09/2009 6:16 AM

You are supposed to know this.

Your previous post says you are Graduate in electrical engg and want to pursue Masters Degree. I am not sure about or

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#4
In reply to #1

Re: Neutral

02/09/2009 8:33 AM

I knew a guy once who had a basic degree, could not get a job, he went back and got a masters degree, guess what still could not get a job, ended up getting a PHD, proves the "Piled Higher and Deeper" theory. He ended up teaching, he should be flipping burgers at McDonalds.

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#5
In reply to #4

Re: Neutral

02/09/2009 11:42 AM

Must have taught students like these

Check other thread - doesn't know what are compensators.

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#7
In reply to #5

Re: Neutral

02/09/2009 11:53 AM

From the sound of it he hasn't started any courses yet, 'working for a real estate company doing maintenance engineering' one has to wonder if he is even a licensed electrician? With any luck someone will point him at a source he can read and learn something, rather than spoon feeding.

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#8
In reply to #7

Re: Neutral

02/09/2009 1:03 PM

Supplying to houses and streetlights. from me, (for poor neighbourhood persons)

No use of advising spoonfeeders.

See Post #6

And they don't know this spoonfeeding is going to create havoc.

Ever heard about a doctor who started prescribing a particular medicine to everybody, since he saw his senior prescribing to the first 3 or 4 (co-incidentally) patients ?

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#15
In reply to #1

Re: Neutral

02/10/2009 2:24 AM

sb,

I really don't get your response, perhaps you can clarify what its purpose is ?

If you don't want to help then don't bother responding.

Point the person in the direction of information if you want to help.

Trying to put someone down because you believe that they should know something is pathetic.

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Mr. W.A Snow

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#17
In reply to #15

Re: Neutral

02/10/2009 3:12 AM

When I am an electrical engineer (I was ages back as per my certificates- however now i am totally away from this subject), the at least I am supposed to know

a) What is a floating neutral and what is a grounded (or earthed) neutral (a third type too is available)

b) What are the transformer primary connections and neutral conditions and ditto for secondary (it also may be clarified that it is not always optimum to have same configurations for the primary and secondary)

The subject is vast and this is not a class room.

The OP was just asked to polish up his text books.

And it is not the quastions of my believing that he should know. It is the question of an electrical engineering graduate knowing the basics.

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#18
In reply to #15

Re: Neutral

02/10/2009 4:28 AM

There is a safety area that should be observed, we are not just discussing a cake recipe, if something goes wrong with a power connection because someone did not observe or understand the dangers, people could get hurt!!! or worse......

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#19
In reply to #18

Re: Neutral

02/10/2009 5:44 AM

True. But that does not give somebody the right to try and be-little someone else. If one is concerned with the safety issue and believes that the person requesting the information is not qualified then simply do not answer the post - that, I think is not that difficult.

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#20
In reply to #19

Re: Neutral

02/10/2009 5:54 AM

As per your advice ignoring this.

However it becomes a bit difficult to live with ostrich syndrome.

Ignore somebody doing wrong ?

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#23
In reply to #20

Re: Neutral

02/10/2009 6:33 AM

Your original reply was not to assist or educate the requester of the information. Its sole intention was to try and be-little someone for asking a question - not really sure what sort of kick you get out of this.

Suddenly, you then jump on the "safety issue" in a feeble attempt to justify your behaviour. You are now trying to come across as the concerned citizen and it clearly does not suit you.

If the intention of the original poster was to perform an act that would endanger himself/herself then it is highly unlikely that that person would be requesting information. It would appear that the original poster realized the he/she has a knowledge deficiency in this area and is trying to rectify this.

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#21
In reply to #19

Re: Neutral

02/10/2009 6:25 AM

There I must disagree with you. If that's what it takes to give them a heads up, then that's what it takes......

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#22
In reply to #21

Re: Neutral

02/10/2009 6:32 AM

Did you see #17,

Just to reminisce- Based on the transformer, pri and secondary connections you can only say whether and which neutral should be floating and which one should be fixed or earthed. There is no general purpose rule here.

You have to explain the zero sequence currents to get to the root.

Logging out of the discussion. See you in another thread.

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#25
In reply to #22

Re: Neutral

02/10/2009 6:55 AM

Best wishes, looking forward to seeing you again, you were right......

You got his attention I am sure and you may have prevented a serious accident too....who knows!

One does not have to be "nice" on such occasions, one needs to effectively settle a safety issue.....no matter what it takes.

I personally find such questions totally wrong in the first place, how can anyone start asking questions without first learning about the subject, CR4 is not Electricity 101, nor will it ever be........but some people simply do not understand that......

best regards

Andy G.

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#2

Re: Neutral

02/09/2009 6:28 AM

A grounded neutral will remain substantially at zero (earth) potential, even under fault conditions.

A floating neutral has the ability shift dramatically, and in the worst case can assume a voltage that is equal to a phase-phase voltage.

In a supply system, where the neutral is earthed (grounded), appliance and installation damage occurs should the neutral connection be compromised, such as when the neutral connection becomes open circuited, or becomes a high impedance, such as at a distribution transformer or in a dead end street.

What drives the voltage on the then floating neutral is the impedances of appliances connected between phases and neutral in installations.

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#3
In reply to #2

Re: Neutral

02/09/2009 8:30 AM

You really have to stop answering home work questions, just point them towards the information so they can find it for themselves. how else are students going to learn.

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#6

Re: Grounded Neutral vs. Floating Neutral

02/09/2009 11:45 AM

A grounded neutral will prevent overvoltages in a system as compared to floating neutral. In a floating neutral system, a ground on the system may cause up to a 66% increase in voltage for one phase on a three phase system.

this is the direct result of the fact that when on phase is grounded the neutral point is moved so that zero volts with reference to ground occurs at that phase...and the other two phase voltages become elevated.

The other advantage of a grounded neutral is that is will immediately cause a fuse to blow or a breaker to trip......on the other hand....in a three phase system it may only cause on phase to blow it fuse which will result in you running your motor loads on an unbalance system.

Tom

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#9

Re: Grounded Neutral vs. Floating Neutral

02/09/2009 10:44 PM

If your device is not grounded then it has a floating Neutral which can be very unhealthy when there is a short in the device

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#14
In reply to #9

Re: Grounded Neutral vs. Floating Neutral

02/10/2009 1:57 AM

I am not sure that it will be un-healthy if a neutral has a short

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#10

Re: Grounded Neutral vs. Floating Neutral

02/09/2009 11:26 PM

A floating neutral or ungrounded system is a high reactance capacitance grounded due to the coupling of every point of the conductor to ground.

If you want to learn more refer to IEEE Std. 141 chapter 7.

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#16
In reply to #10

Re: Grounded Neutral vs. Floating Neutral

02/10/2009 3:04 AM

Patriotism is the last refuge of scoundrels. I resent that comment all though I believe in the freedom of speech. I am a Patriot of the Philippines. I was born in the USA but have lived in the Philippines for more than 25 years. I am a member of what some call the left. We are Patriots. We love our country and resent being called a scoundrel. I would die for my Country, the Philippines. gbuddyw@gmail.com

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#11

Re: Grounded Neutral vs. Floating Neutral

02/09/2009 11:28 PM

If the entire system is no where grounded the balances of the loads on the phase legs will make the neutral hot. Red leg drawing 80 amps. Blue leg drawing 60. Yellow leg drawing 40. Backfeed to neutral is 20 40 60. No ground, Neutral hot for 300 hundred amp system. Check with the rest. I could be wrong. Its been ten or so years since I tied in. Still Ground first, neutral second, hot legs next and reverse for disconnect. (I think we tied into a school in PA expecting a ground, but there was none.) -My electrician was Tom Potoski who was the Dolly grip on SlingBlade. Balance of loads was his job and partly mine. Got sticky. That's what I remember. Nobody fried, and no lamps blown.

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#12

Re: Grounded Neutral vs. Floating Neutral

02/09/2009 11:41 PM

P.S. Did that add up to 100 on single phase? Give the kids a break guys. I hardly remember what I did and we're all together sometimes wondering what we're doing. May as well help a kid with their homework now and then. Gottah give 'em some credit for knowing who to ask. Take it as a compliment. I learned all I know in the streets and have no shame about asking for a Best Boy.

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#24
In reply to #12

Re: Grounded Neutral vs. Floating Neutral

02/10/2009 6:38 AM

I think answering questions for students easier to stomach when someone simply explains their big project and asks a directed question about on of the related concepts instead of a solution to the whole thing. There are lots of helpful individuals who will help explain a. While this thread falls a into this category I have a problem with the symantics.

Since this is an open forum and nobody can expect or demand more than what they pay for here, I consider it good etiquette to finish a post with a polite question and a courteous close. Not "Please Advise" like is used in corporate environments when one department needs something from another.

Anyway, I'd rather he get some answers and nobody get hurt...but this is what a formal education and certification is supposed to guarantee.

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#13

Re: Grounded Neutral vs. Floating Neutral

02/09/2009 11:44 PM

my numbers are wrong.

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#26

Re: Grounded Neutral vs. Floating Neutral

07/23/2013 11:54 PM

Dear Mr.cyannt

Pl. read here - alot of subjects are discussed.

http://electrical-engineering-portal.com

DHAYANANDHAN.S

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#27

Re: Grounded Neutral vs. Floating Neutral

07/24/2013 4:31 AM

Nice bringening threads back from the dead

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#28
In reply to #27

Re: Grounded Neutral vs. Floating Neutral

07/24/2013 4:52 AM

Dear Mr. Epke,

Is it BRINGING.? or BEGINNING.?

Pl. make this clear.

DHAYANANDHAN.S

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#29

Re: Grounded Neutral vs. Floating Neutral

09/25/2024 6:28 AM

There is an article in Wikipedia on Earthing Systems. It's the difference between an IT system, and everything else.

Go and find it; the journey will be worthwhile.

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