How Predictive Maintenance of Circuit Breakers Boosts Reliability While Cutting Costs

In this two-part series, I’ll discuss some new techniques and technologies that can make your circuit breaker maintenance routine more efficient and effective.

I’m sure you’ll agree that keeping up with equipment maintenance can sometimes be a challenge, especially with limited resources. But, of course, the safety and reliability of your facility depends on it. For circuit breakers in industrial plants or commercial buildings, maintenance has usually followed a preventative approach, with regularly scheduled checks and testing. This is typically done every one or two years, whether each breaker actually needs it or not.

With most facility teams looking for ways to optimize the performance of their infrastructure, there’s increasing interest in alternative maintenances strategies. Fortunately, recent advances have been made in terms of the intelligence of circuit breakers, as well as new analytic capabilities at the software level. These have enabled a more condition-based approach, based on real operational and environmental inputs. The actual health of each breaker can now be predicted, as it relates to aging and other risks.

Based on this information, facility or contracted maintenance teams can tailor their maintenance schedules to perform servicing on each breaker when it’s needed. Risks can also be revealed that point to breakers needing more urgent attention, including replacement. It all adds up to improved safety and less downtime. But it can also mean getting longer life out of equipment while spending less time on maintenance.

So how does this all work? First, we need to look at the two different sets of conditions that cause a circuit breaker to age and require maintenance.

· Operational conditions. Mechanical wear is determined mainly by the number of times a breaker opens or closes, as well the number of times its protection mechanism trips due to an overload or short circuit. But to truly gauge the wear on a breaker’s contacts – and, therefore, service life – you also need to take into account the amount of current flowing during each of these actions. More current, more wear.

· Environment conditions. Harsh environments can accelerate aging. High ambient temperatures, high power harmonics, and high load levels all contribute to higher overall operating temperatures. There could also be corrosive elements present, such as high humidity, salt, gases, or airborne oil particles. Finally, dust and mechanical vibration can each add to the stresses on a circuit breaker.

To fully optimize the service life and performance of a circuit breaker, a maintenance program should take into account all of these operational and environmental influences on aging. But what kind of maintenance strategy is best?

Let’s consider the pros and cons of each common type of circuit breaker maintenance.

· Reactive maintenance. Using a reactive method allows circuit breakers to fail before being taken out of service and replaced. This might be a reasonable approach in situations where productivity or safety are not affected, as it can represent the lowest maintenance time and costs. But those savings can be lost due to shorter equipment life and therefore more frequent replacement, as well as the potential damage to secondary equipment.

· Preventative maintenance. This is the more typical approach in most facilities. Periodic checks are done to reduce the probability of breaker failures and extend their life span. Specific maintenance intervals are recommended by the manufacturer, or by electrical or safety organizations. These take into account general operating and environmental conditions. The approach helps minimize failures and, in turn, maintenance and equipment costs. However, it’s more labor-intensive than the reactive approach and can sometimes result in unnecessary servicing. On the other hand, maintenance might not be done often enough if conditions affecting aging aren’t estimated accurately, or if they change over time.

· Predictive maintenance. By acquiring a continuous stream of operational data from circuit breakers and environmental data from other facility systems, service teams can quantify real-time conditions affecting each breaker’s performance. This strategy has a number of benefits over the preventative method. Maintenance can be done only when it’s required, avoiding unnecessary shutdowns. Imminent failures can be anticipated, avoiding downtime. And Inventory can be reduced, with parts ordered on an on-demand basis. ARC Advisory Group summarizes this as a 50% reduction in maintenance costs, a 55% reduction in unexpected failures. However, this method requires an initial investment in a supporting diagnostic system.

Clearly, preventative, condition-based maintenance can deliver greater facility uptime and savings. Fortunately, the supporting diagnostic tools required are now becoming available. These include smart breakers such as the MasterPact™ MTZ series from Schneider Electric, new software analytic capabilities like those included in EcoStruxure™ Power Monitoring Expert, and service options. We’ll look more closely at these in my next post.

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