Grace Case Study-Hot Spots from harmonics and high inrush

Preventing critical breaker failures and extending equipment life using continuous temperature monitoring

Excessive inrush currents combined with harmonics triggered by Variable Frequency Drives (VFDs) in large motor applications put severe thermal burden on electrical components that are connected in the system. These conditions often lead to unpredictable early failures in key electrical components such as circuit breakers, bus bars and other terminations.

While some of the leading indicators of failure include over heating of contacts, and frequent breaker tripping; others are catastrophic breaker failures that significantly impact the plant productivity metrics and uptime. Breaker failures tend to be very expensive in situations where they are connected to critical feeders, and replacements are either not readily available or difficult to find. In addition, the availability of a spare breaker, and well trained resources to perform the work could take anywhere between couple days to a week.

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