Polarization Index (PI) Value

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Anonymous Poster	Polarization Index (PI) Value 08/08/2009 4:48 AM
	Recently one of our new generator ( 165 MW capacity) was failed due to rotor earth fault. Before startiong the machine we took the megger value and PI value. That time PI value was 4. Is it acceptable to run the machine with higher PI value?
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sb Guru Join Date: Mar 2007 Posts: 2550 Good Answers: 103	#1 Re: PI value 08/08/2009 5:50 AM
	Polarisation Index of 4 does not look bad. What are the other test results and what is the shape of the curve? If they are OK it must be healthy. __________________ Fantastic ideas for a Fantastic World, I make the illogical logical.They put me in cars,they put me in yer tv.They put me in stereos and those little radios you stick in your ears.They even put me in watches, they have teeny gremlins for your watches
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Siswanto Commentator Join Date: Mar 2008 Location: JAKARTA. INDONESIA Posts: 73 Good Answers: 15	#2 Re: Polarization Index (PI) Value 08/08/2009 8:09 AM
	Dear guest.. pls visit the following blog address, it our project experiences for repair, testing and inspection of power generation,,,, last year we rewound rotor GE generator 237 MVA, 3000 RPM... www.sispowergeneration.blogspot.com Siswanto __________________ LOVE FORUM AND DISCUSSION
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Anonymous Poster	#4 In reply to #2 Re: Polarization Index (PI) Value 08/10/2009 4:04 AM
	Very good Blog site. The metrials presented in the glog will be much usefull to all in the field
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harry potter Power-User Join Date: Nov 2008 Location: India Posts: 333 Good Answers: 6	#3 Re: Polarization Index (PI) Value 08/08/2009 10:37 AM
	wHAT IS THE MEGEGR VALUE ? __________________ Exploring the Science of Electricity
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melaia Participant Join Date: Jun 2009 Location: Johannesburg, South Africa Posts: 4	#5 Re: Polarization Index (PI) Value 08/11/2009 5:54 AM
	I agree with Harry Potter in asking what the Megger Value is. In other words, what is the Insulation Resistance. This is far more important than the PI because PI only indicates whether the winding is dry or wet, or severely contaminated - on the basis of a (low or suspect) Insulation Resistance (IR) reading. For a healthy dry rotor (??) the IR at 40 deg C should be 50 megohms or more to be confident of a good winding. The PI of 4 indicates a dry uncontaminated winding but the IR value itself is more important in determining the overall winding condition. Good luck. __________________ Robert Melaia (We can never know our first principles well enough)
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Anonymous Poster (1); harry potter (1); melaia (1); sb (1); Siswanto (1)

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