Condition Monitoring: What Are We Measuring?
In essence, one needs to know what they are trying to prevent and what the conditions are leading up to the failure or anomaly before the problems can be prevented. An immediate response to this is often all encompassing, where the personnel responsible for running a process may believe they want to measure everything and monitor trends. However, measuring everything and everywhere can become prohibitively expensive. In a world where costs are of no consequence, this would surely be the most comprehensive way to proceed. But it is just not always realistic. The price of all the sensors, the gateway, and the integration and display of all that information simply becomes too overwhelming and costly. The return on investment (ROI) coming from what problems can be captured is too much of an unknown to justify the shotgun approach of putting sensors on everything everywhere.
Alternatively, zeroing in on the most likely failure points and applying monitoring techniques to those points can be a more-efficient procedure.
In automation and control, often end users are looking to get in front of potential failures so plans can be produced ahead of time. Thus, they will often ask for a list of every possible failure to anticipate. This kind of request can be typical but is also very difficult to address comprehensively. A list of troubleshooting information from the user manual can certainly be helpful, but it won’t ever be “every possible failure” that may occur. There are some events that just can’t be foreseen…such as someone accidentally spilling a bucket of water into an electrical cabinet! Of course, it is possible that electrical cabinet could have had a leak detection sensor in it, but planning for that kind of mishap would be nearly impossible.
What Failures Should You Try to Prevent?
What if you have had a particular problem or know exactly what problem you are likely to see, however? For example, if there has been a past failure that you absolutely don’t want to happen again, it is far more plausible to take an educated guess about what you may need to monitor. Or if other similar companies have persistent challenges, this may lead you in a direction to know what to keep an eye out for. In these situations, the wise application of condition-monitoring sensors can save a substantial amount of money and headaches.
A Case Study in Condition Monitoring
After each of these costly events, the customer had to replace 8 to 10 VFDs, costing them roughly $10,000, not including their labor and downtime. Each time they were down for several hours while they pulled together spares or stole units from less-necessary systems to get back up and running. When the room filled with steam, they were down roughly 8-10 hours. If a company’s downtime costs $10,000 per hour, the one event cost them more than $100,000.
Last year the company began to think about how to catch these problems. At the same time, the Valin team introduced them to condition-monitoring sensors for vibration and temperature, which are the first data points that typically come to mind when operators think about preventive maintenance. However, these sensors also have a humidity option, which is what really caught their attention.
The customer is also able to monitor the temperature in the control room with the same sensors. It has two air conditioning units for the control room because of the climate. VFDs tend to fault out around 140 degrees F. Thus, the customer set their alarm point at about 110 degrees F with the expectation that it will catch the failure of either one of their AC units.
Condition Monitoring Sensors with Multi-Function from Balluff
When another leak event does happen again, the company can rest assured protections are in place. The operators know what the failure mode has been, exactly what information they need, and the steps they need to take to keep it from being a more expensive failure.
Preparing for the Future
Article featured in Design News Magazine.
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