Do you postpone changing your car tires until they blow out? Or do you change tires well before the tread is gone? What about your electrical system? Is your electric room aging and possibly nearing the end of its life expectancy? You want to get the most out of your equipment, but aging infrastructure is an imminent issue. The hard truth is that 80% of transformers fail between 40 and 50 years old. By year 10, 50% of circuit breakers no longer function per specification. This statistic jumps to 90% by year 20.
The general rule of thumb for electrical systems is a life expectancy of 20-30 years. After that you’re in the wear out period. When planning long-term plant expenditures or electrical system retrofits, a good place to start is determining the age of your electrical system. Once you know this, you can begin to anticipate when your equipment is no longer operating per specification or is likely to fail completely.
Let’s take a closer look at when electrical equipment is likely to wear out. In the “bathtub” curve in Figure 1, there is a much higher failure rate for equipment at the beginning and the end of its life cycle. At the beginning of a component’s life, there is a much higher “infant mortality rate.” Failures are typically due to a manufacturing issue, a missing or incorrectly installed part, or a defective piece of equipment. As time progresses, failure rates decrease, and the equipment moves into its “useful life period.” During this phase, there is a low “constant” failure rate. While you may have to replace parts or do maintenance work, this is when fewer equipment failures are encountered. Over time, with wear on the equipment, the failure rate begins to steadily rise. When equipment becomes less dependable, you are entering the “wear out period” for the component.
Determining the age of your equipment and system allows you to plan for improvements or replacements. Rather than being caught off guard by an end of life failure during the “wear out period.” Table 1 shows the expected life of various types of well-maintained electrical equipment.
Consider the risk of a blowout on a car with 4 bald tires versus just one. Or picture an entire fleet with bald tires. The odds of a blowout just dramatically increased. This also holds true for sites with multiple aging electrical components. Failures are likely as equipment ages, and ignoring the signs of aging equipment will likely cost you in unplanned downtime and costly repairs. Finding replacement parts will also become a challenge as parts for older equipment become obsolete.
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Doug Post, Interstates Engineering President