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Anonymous Poster

Generator protection

09/11/2008 2:43 AM

Dear sir,

Why stator winding of a generator cannot be protected 100%.
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Sparkstation
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#1

Re: Generator protection

09/11/2008 2:54 AM

Hello "Guest"

Protected from what?

  1. Birdstrike
  2. Flooding
  3. Earthquake
  4. Fire
  5. Explosion
  6. Gas discharge
  7. Meteor strike
  8. Airplane strike
  9. Meltdown
  10. ...The list goes on, and on, and on.....

Reply here, with

Kind Regards....

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ktel60
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Join Date: Apr 2006
Location: Texas, by God! Houston for precision
Posts: 167
Good Answers: 2
#3
In reply to #1

Re: Generator protection

09/11/2008 11:51 PM

Seriously. Are you talking about overvoltage, undervoltage, power source variabilities?

Answer: Isolate unit in asteroid

Launch into Space

Somebody else's problem

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Sparkstation
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#5
In reply to #3

Re: Generator protection

09/12/2008 3:38 AM

Hello ktel60

If you read the original question, you should see that it is poorly formed.

For a proper answer to be given, variables must be eliminated.

Otherwise there may be hundreds or even thousands of different answers, because the Question is "Open-ended".

Sometimes it is possible to guess the intent of the question, but if this is done, even though the answerer may give the correct answer, the question asker will never learn to correctly pose future Questions.

We are not mind-readers here, we do our best to help others.

An Question which does not properly specify the problem, is only correctly answered by guesswork, and Engineers do not guess, because they deal in definite things, terms and so on.

Kind Regards....

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suresh sharma
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Good Answers: 25
#9
In reply to #5

Re: Generator protection

09/13/2008 3:21 AM

Sparky,

Here we get many questions from the "Guests" who are either students or freshers from college,so we have to assume normal lingo of the questions. Here protection means normal protection provided for the motor windings which is overload or short circuit,as I am not expert in Electrical Technology so better you answer it.I know for normal motor we have to provide O.L.Relay and HRC fuse for overload and short circuit protection. You may alternately provide MCB.For Alternator I am not aware of the protection provided.

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Anonymous Poster
#2

Re: Generator protection

09/11/2008 9:44 AM

Somebody obviously enjoy from others scoffing! It is not good for them and others.

But about technical question,

When the 59GN is applied in a GFN scheme amplification of the 60 Hz zero-sequence voltage may require a much higher setting on the 59GN relay.Generators can produce significant zero-sequence harmonic voltages during normal operations.

These harmonic voltages will appear across the secondary resistor and voltage relay. The most significant is the third harmonic, which can be from 1 to 10% of the generator terminal voltage. If the 59GN relay is to be set near 6 V to achieve 95% coverage of the stator winding, the relay used must be tuned to fundamental frequency (60 Hz) rendering it insensitive to third and other zero-sequence harmonic voltages.

So the neutral overvoltage and broken-delta schemes can detect faults over 95% of the winding, but the 5% near the neutral is unprotected.

If a second ground occurs in the same phase near the generator terminal it will be undetectable and unrestricted by the grounding impedance. The generator differential relay would not operate for this fault, because current at each end of the winding would be the same. This extremely high magnitude fault would persist until it evolved into a phase-to-phase fault that is detectable by the differential relay.

As a result of these considerations and the development of electronic relay technology, several 100% winding protection schemes are now available. They fall into two categories: third-harmonic voltage schemes and neutral injection schemes.

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Anonymous Poster
#4
In reply to #2

Re: Generator protection

09/12/2008 12:41 AM

Thank you for your answers.

regards,

kailash
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Anonymous Poster
#7
In reply to #4

Re: Generator protection

09/12/2008 11:08 PM

please be more vague next time.

Thanks,

Sparkstation.
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Sparkstation
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#8
In reply to #7

Re: Generator protection

09/13/2008 3:08 AM

That comment not by me.

Kind Regards....

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dadw5boys
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Good Answers: 23
#6

Re: Generator protection

09/12/2008 7:47 AM

BECAUSE GALCIER ICE IS MELTING AND SINKING THEM UNDER THE ICE WOULD COST TO MUCH TO RUN THE CABLE SOUTH OR NORTH.

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Anonymous Poster (3); dadw5boys (1); ktel60 (1); Sparkstation (3); suresh sharma (1)

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