— BY DR . S IRI VAR ADAN, PE, DIREC TOR OF GLOBAL PRODUC T MANAGEMENT, ENTERPRISE SOF T WARE PRODUC T GROUP

Finding the “right” test:What the human heart can teach us about asset performance management.

2 FI N D IN G TH E “ R I G HT ” TE S T

—From tennis to transformers...

A recent emergency room (ER) and hospital experience took me from the tennis court to the operating table for an emergency triple coronary arterial bypass graft, all within 36 hours.

Electrical asset managers take a similar approach. For example, we measure Furans or parts per million of various compounds (water, ethylene, acetylene, etc.) in the oil circulating in a transformer and alarms are triggered when established thresholds are exceeded. But does this sort of testing really get you to the root of the problem and serve as an accurate predictor of impending failure? Is there one single test, or are multiple tests required for meaningful health assessments? Is one type of test more significant than another, based on the inherent failure mechanism of the asset?

During the eight-week-long recuperation, I had a lot of time to think about that critical asset – my heart – and how close it came to failure. Then my inner geek just could not help comparing it to the way electrical assets work, and fail. I wondered if electrical assets (say, for example, transformers) exhibit characteristic behaviors before their last gasps and eventual failure. Further, could monitoring these characteristic behaviors and taking precautionary measures help to avoid the failure altogether?

Again, my inner geek was intrigued and the questions continued. What behaviors do assets exhibit leading up to their failure? What measurements would capture such behavior? What sensors would be needed to capture such measurements? What patterns would we look for? And finally, how would we make sense of all the data in terms of imminent failure and remaining life?

Knowing a lot is not the same as knowing enough“Human asset” managers (i.e., doctors) have known for decades that blood cholesterol (total, high-density

lipoprotein – HDL, and low-density lipoprotein – LDL) plays an important role in heart attacks. They advise that the ratio of HDL to LDL is very important: HDL must be high while LDL must be low. They also know the threshold numbers that are cause for alarm and know when prescriptive medication needs to be administered based on these thresholds.

Numbers don’t lie…but they may not tell the whole truthAt my health assessments – AKA routine physicals – my cholesterol

numbers looked great, and I was assured that there was no need for alarm. Nevertheless, an invasive test conducted only after I suffered a heart attack revealed that I had three arterial blockages. In other words, no amount of looking at my cholesterol numbers would have given me, or any competent doctor, an indication of the level of calcification in my arteries, which is a much truer indication of heart health. I had to exhibit the classic symptoms of a heart attack and be admitted to the hospital before an angiogram would be done to determine if I had any coronary arterial blockages. If I had not been strong enough to survive the heart attack, the useful test would have been just a little late.

Similarly, no one wants to realize what they could have evaluated after a critical asset such as a transformer has already failed and the company is facing millions in damages (and millions of unhappy customers). What if we are looking at the wrong numbers and drawing erroneous inferences? Are the tests we routinely conduct even significant?

W H AT TH E H U M A N H E A RT C A N TE ACH US A B O U T A SSE T PER FO R M A N CE M A N AG EM ENT 3

—Catching failure in the act

Does end of life and failure announce itself in the form of an unfolding event in time, however short or long?

In the case of the human heart, external attributes such as blood pressure, oxygenation level, heart rate and body temperature could all be indicative of a heart problem, but not conclusively! The goal is to see the amount of calcification in arteries as a predictor for coronary blockage. The same is true in the case of a transformer – much can be measured, but the goal is to examine the degree of polymerization or thickness of the paper used in the windings of a transformer as a predictor for short circuits. Without an invasive test, it would be very difficult to examine the degree of polymerization or measure the thickness of the insulating paper.

kV) transformer fleet. In fact, AEP has archived key data associated with events leading up to a failure and uses these patterns in their asset monitoring system (ABB Ability™ Ellipse® APM – a software product provided by ABB) to detect impending failures. AEP’s PD-OL program has been so successful that they are in the process of extending this monitoring capability to the remainder of its fleet. The business justification is quite simple, as the cost of such monitoring is a small fraction of what a potential failure could cost.

Another example of catching a failure “in the act” was reported by AEP as a result of its enhanced asset monitoring capability. Heavy gassing activity was reported at one of its substation transformers, and the operator was instructed to power down the asset. Further invasive testing revealed that the transformer would have experienced a catastrophic failure had the preventive action not been taken. Again, as in the case of the PD-OL failure that was recorded as it unraveled, the monitoring of gases proved to be a good indicator of impending failure.

Catching failure in the actGiven that invasive tests are prohibitively expensive or not yet technologically feasible, the question

then becomes, what is the next-best alternative? What other kinds of monitoring would allow an engineer to make an effective, holistic evaluation of an asset’s condition? In other words, is there some way to continuously monitor the health of an electrical asset and predict impending failure?

Fortunately, partial discharge online monitoring (PD-OL) is a non-invasive monitoring technique that allows asset managers to watch out for impending failures based on classic electrical characteristics exhibited during a failure event that could last several days. This technique has been shown to be very effective in the literature for electrical assets, including transformers and cables. The technique has also been implemented by American Electric Power (AEP), one of the largest electric utilities in the USA, on its EHV (765

It’s all about the data – all of the dataSo is there any one test that works to indicate impending failure for electrical assets? Regrettably, no.

It is a combination of things that a subject matter expert must look at, much like a doctor, to determine what exactly is going on.

While some tests are more significant than others, all the data needs to be assessed to make an accurate determination of the situation. This is exactly what I learned under great duress in the ER. Results of multiple tests had to be assessed by the attending physician to determine with certainty that I was experiencing a heart “event” that, if left untreated, could have led to my death (as you may imagine, I’m quite keen to avoid that particular “asset failure”)!

4 FI N D IN G TH E “ R I G HT ” TE S T

—A different kind of doctor

As asset management personnel, we are a different kind of doctor, caring for extremely complex and often widely-dispersed assets. We need to

assessment of data by expert models that are embedded in the software platform. In other words, Ellipse APM serves as a “doctor of electrical assets” working in a highly parallel processing mode as all assets are evaluated simultaneously using built-in expert system models. Asset health is determined on a periodic basis and preventive actions (both short-term and long-term) are prioritized – you might even say triaged.

As for me, I’m fully recovered and back at work, and my doctor and I will continue to use all of the data available to us to ensure I don’t have another “event.” That’s a goal for asset managers everywhere, and one that’s attainable with the right approach, supported by the right technology.

—Dr. Siri Varadan, PE, is director of product management for ABB's Enterprise Software product group. He drives the company’s research and development of analytics solutions such as ABB Ability Ellipse APM.

deal with data from multiple assets at the same time. The sheer diversity in asset types and their individual numbers is staggering, not to mention the copious amounts of data each asset produces. The logical conclusion is that we need an “expert” system to analyze all this data to make meaningful predictions of health, remaining life and timely intervening actions. Fortunately, this is where technology and the ability to codify expert knowledge comes in handy.

ABB Ability™ Ellipse® Asset Performance Management (APM), formerly known as Asset Health Center, is a leading industry example that addresses this situation very appropriately. Capturing decades of subject matter expertise (manufacturing, operational and repair/re-engineering) in electrical assets in the form of software models, Ellipse APM allows the

—abb.com/enterprise-softwareinfo.pges@abb.com

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