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Application Notes:
Loose or Corroded Electrical Connections |
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Thermal images of electrical systems can indicate the operating condition of the equipment in those systems. In fact, since the beginning of thermography more than four decades or more ago, the principal commercial application for thermal imaging has been electrical system inspection.
The reason thermography is so applicable to the monitoring of electrical systems is that new electrical components begin to deteriorate as soon as they are installed. Whatever the loading on a circuit, vibration, fatigue and age cause the loosening of electrical connections, while environmental conditions can hasten their corroding. Detecting and correcting failing connections before a fault occurs averts fires as well as impending shutdowns that can be critical to manufacturing, commercial and institutional operations.
What to check?Check panels with the covers off and power at ideally at least 40 % of the maximum load. Measure the load, so that you can properly evaluate your measurements against normal operating conditions. Caution: only authorized and qualified personnel using the appropriate personal protective equipment (PPE) should remove electrical panel covers.
What to look for?In general, look for connections that are hotter than others. They signal high resistance possibly due to looseness, tightness or corrosion. Connection-related hot spots usually (but not always) appear warmest at the spot of high-resistance, cooling with distance from that spot. As noted, overheating connections can, with additional loosening or corrosion, lead to a failure and should be corrected.
What represents a "red alert"?Equipment conditions that pose a safety risk should take the highest repair priority. Guidelines provided by the NETA (InterNational Electrical Testing Association) say that when the difference in temperature between similar components under similar loading exceeds 15 C (27 F) immediate repairs should be undertaken.
What's the potential cost of failure?Left uncorrected, the overheating of a loose or corroded electrical connection could blow a five dollar fuse and bring down an entire production process. Then, it will probably take at least half an hour to shut off the power, get a spare fuse from the storeroom, and replace the blown fuse.
Follow-up actionsOverheating connections should be disassembled, cleaned, repaired and reassembled. If, after following this procedure, the anomaly persists, the problem may not have been the connection, although a faulty repair remains a possibility. Use a multimeter, clamp meter or a power quality analyzer to investigate...
Click here to download the full pdf: Loose or corroded electrical connections » | |
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