Tell a Friend About CR4
Engineering Toolbar
Search GlobalSpec
Login | Register
Home | Electrical Engineering | Electrical Engineering | PI for Generator Rotor

Previous in Forum: How to Synchronize CAT C18 Model Diesel Engine   Next in Forum: Futher Electrical Power
Close

Comments Format:






Close

Subscribe to Discussion:

CR4 allows you to "subscribe" to a discussion
so that you can be notified of new comments to
the discussion via email.

Close

Rating Vote:







3 comments
Subscribe Rate this Comments: Nested
scooby1981
Member

Join Date: Sep 2009
Posts: 5

PI for Generator Rotor

11/05/2009 4:21 AM

I have tested rotor of 30 MW gas turbine 2-pole generator and the results are as under:

Insulation resistance = 33,882 Mohms

Dielectric absorption ration (IR60 second/IR30 second) = 1.10

PI = 1.46

Dielectric discharge ratio = 0.66

I would like to know the minimum acceptable DAR and PI values for healthiness of the generator rotor.
Send to a friend Digg this Add to del.icio.us
Interested in this topic? By joining CR4 you can "subscribe" to
this discussion and receive notification when new comments are added.

Comments rated to be "almost" Good Answers:

Check out these comments that don't yet have enough votes to be "official" good answers and, if you agree with them, rate them!
PWSlack
Guru
United Kingdom - Member - Indeterminate Engineering Fields - Control Engineering - New Member

Join Date: Jan 2007
Location: In the bothy, 7 chains down the line from Dodman's Lane level crossing. Kettle's on.
Posts: 8653
Good Answers: 164
#1

Re: PI for generator rotor

11/05/2009 4:43 AM

What does the original equipment manufacturer's operation and maintenance manual have to say on the topic?

__________________
The elephant is a funny bird. It flits from bough to bough. It lays its eggs in a rhubarb tree and whistles, like a cow - Spike Milligan.
scooby1981
Member

Join Date: Sep 2009
Posts: 5
#2
In reply to #1

Re: PI for generator rotor

11/05/2009 5:00 AM

As per GE - A field index (PI) of 1.25 would suggest a clean, dry field winding.
msamad
Power-User

Join Date: Feb 2009
Location: Houston, USA
Posts: 219
Good Answers: 44
#3
In reply to #2

Re: PI for generator rotor

11/05/2009 4:27 PM

(1) Dielectric Absorption Ratio (DAR) = (IR 60 seconds / IR 30 seconds)

Recommended DAR values

DAR Values

Result

Less than 1.1Bad
Between 1.1 to 1.5Good
More than 1.5Excellent

(2) Polarization Index (P.I) = (IR 1 minute / 10 minutes)

Recommended minimum values of PI for all machine components insulation classes per IEC 60085-01:1984 or IEEE Std 43-2000

Thermal class rating

Minimum PI

Class A1.5
Class B2.0
Class F2.0

See the following links:

http://www.pacifictest.com.au/documents/Nov_Dec_IE_2008.pdf

http://www.termogram.com/articulos/Understanding_Insulation_System_Testing-Don_Shaw.doc

http://www.coleparmer.com/techinfo/techinfo.asp?htmlfile=AEMC_insulation.htm

- MS
Score 1 for Good Answer
No more "Almost" Good Answers.
3 comments
Interested in this topic? By joining CR4 you can "subscribe" to
this discussion and receive notification when new comments are added.

Comments rated to be "almost" Good Answers:

Check out these comments that don't yet have enough votes to be "official" good answers and, if you agree with them, rate them!
Copy to Clipboard

Users who posted comments:

msamad (1), PWSlack (1), scooby1981 (1)

Previous in Forum: How to Synchronize CAT C18 Model Diesel Engine   Next in Forum: Futher Electrical Power
You might be interested in: Electrical Power Generators, DC Servomotors, Ion Specific Electrode Meters


"You cannot escape the responsibility of tomorrow by evading it today" -- Abraham Lincoln

All times are displayed in US/Eastern (EST) (Register to change time zone)

©2005-2009 GlobalSpec. All rights reserved.
GlobalSpec, the GlobalSpec logo, SpecSearch, The Engineering Search Engine
and The Engineering Web are registered trademarks of GlobalSpec, Inc.
CR4 and Conference Room 4 are registered trademarks of GlobalSpec, Inc.
No portion of this site may be copied, retransmitted, reposted, duplicated or
otherwise used without the express written permission of GlobalSpec Inc.
350 Jordan Rd, Troy, NY, 12180

Got Something to Say?


Search this Forum
Electrical Engineering:

Search all of CR4

CR4 Sections
Automotive
BioMech & BioMed
Chemical & Material Science
Civil Engineering
Communications & Electronics
Education
Electrical Engineering
Engineering Careers
General
Instrumentation
Manufacturing
Mechanical Engineering
New Technologies & Research
Software & Programming
Sustainable Engineering

Site Indices
Forum Index
Blog Index
User Group Index
RSS Feeds
CR4 Store

CR4 FAQ
Site Glossary

Who's Online (131 right now)
Show Members