I am looking for advice on
- Technologies for predicting remaining life of ageing motors and transformers
- Typical modern test equipment and instruments used this purpose
- Success/Failure stories or weblinks

Appreciate any help that readers can offer.

We use IR camera on live front connections. Our 13.8 kV cabling is shielded and amoured so not much can be done with it as far as corona detection. We changeout transformers at 25 years irregardless of condition. Also change the primary cabling as cheap insurance. I have 6.5 miles of 13.8 cabling and 48 main building transformers.

Vee,

ABB has a service handbook for power transformers. Would assume other large manufactures would have similar books.

Mark

Some documents that may interest you:
EPRI Report 100185 Motor And Generator Life Estimation
IEEE 943 - IEEE Guide for Aging Mechanisms and Diagnostic Procedures in Evaluating Electrical Insulation Systems.

For transformers, CO and CO2 and temperature history may give a rough idea of thermal aging rate. Furan analysis gives a better and corroborating measurement, especially for cuumulative aging. Best insulation analysis would be obtaining a small sample of paper for DP analysis. And while you're in the transformer, do a thorough visual inspection of accessible portions of the winding and clamping system along with bushings, connections etc. Review history of through faults (each through fault may take away some life). Also I guess Doble is looking at F.R.A. and changes in leakage reactance for indication of winding movement. Get an expert to review all this along with the electrical results (such as Doble) and oil results, and you may be up to the level of a SWAG.

For rotating machines, internal inspection will be very helpful as well. Surge test, dc step voltage test, power factor tests might all be applied to asses insualtion condtion. Again in the end, all you have is a swag.

Knowledge of duty of the machine (environment, operating temperature) and failure history of the family of machines would certainly help.

In case I have not made it clear, I don't think that there is anyting resembling an exact science when it comes to "predicting remaining life"

I thought reliability engineering will apply for this equipment. If I remember correctly, I read in HP Bloch's 4-volume book on how to analyze failure history for big motors in order to decide on their replacement.

Good point Josh. I agree 100%. I had referred to failure history of the family of machines (meaning machines with similar design, enviornment, operating conditions and maintenance history). It is undoubtedly the single most reliable and quantifiable piece of information in the puzzle. The more machine years of detailed history you have, (especially with a range of ages encompassing the age of interest), the better predictions you can make by comparing the conditions of the motor of interest to your history population. IEEE Gold book also has some generic failure informatio which may assist as a starting point although not as good as looking at sister machines. This approach is of course not unique to motors/transformers.

Pete, Mark, Josh,

Thank you all, I appreciate the help.

Vee,

Here is the TOC of the ABB book. It pulls together a lot of diverse sources of information.

Chapters:

1. Transformer Design Considerations.
2. Diagnostic methods for power transformers & Acc.
3. Oil Quality Assessment.
4. Analysis of particles in transformer oil.
5. Dissolved gas in oil analysis.
6. Degree of Polymerization.
7. Furanic compound analysis.
8. Streaming Electrification.
9. Insulation Power factor Tests.
10. Bushings.
11. On-Load Tap Changers.
12. Partial Discharge measurement.
13. Dielectric frequency response measurement.
14. Sweep frequency response analysis.
15. Excitation current Tests.
16. Transformer Turns Ratio Test.
17. Core Insulation Resistance Measurement.
18. Infrared thermography analysis of transformers & Acc.
19. Winding Resistance Test.
20. General maintenance of Transformers.
21. Online diagnostics monitors for transformers and Acc.
22. Failure Statistics for power transformers.
23. A practical approach to assessing the risk of failure of power transformers.


Mark.

Mark,
Thanks; is the ABB book available to the public? Any idea of where to buy a copy?

Vee,

It is available to anyone who wants to buy.
Goto: http://www.abb.com/transformers
click on the link for Service Handbook for Transformers. Looks like they have updated the book since the version I have looked at (Jan 2006).

Mark Holycross