The adage “if it ain’t broke, don’t fix it” is apt when it comes to asset maintenance and one of the drivers behind utilities shifting from time-based to condition-based maintenance. Determining asset condition is therefore crucial for knowing when to act, and a wide range of online and offline test methods exist to feed data into the decision-making process.
Online techniques include survey tools (e.g., infrared, RFI), temporary monitors (e.g., partial discharge) and online monitors (e.g., dissolved gas analysis). These techniques detect developing problems and can be used to trigger maintenance or further investigations. Offline methods measure parameters that cannot be assessed online, however they do require outages. Online and offline techniques provide diagnostic capability to probe the cause of a problem, thereby allowing appropriate action to be planned.
Car maintenance is a good analogy. This might occur every 20,000 miles, or when a warning light comes on (triggered by condition monitoring), or as a backstop, every two years. In this instance, the “online” monitoring detects developing issues (e.g., low tyre pressure) not addressed by the simple (wear and tear) distance metric. The driver is also an onboard “survey” tool detecting unusual noises and vibrations. The car experiences an “outage” when it is taken to a garage and examined using “offline” methods.
Selecting the right tools to detect and diagnose issues early, applying the appropriate analytics and engineering knowledge underpins effective maintenance practice. When it comes to maintenance, “if it ain’t broke, don’t fix it” are good words to remember.