Loose or corroded electrical connections

1 Thermal images of electrical systems canindicate the operating condition of theequipment in those systems. In fact, sincethe beginning of thermography more thanThe reason thermography isso applicable to the monitoringof electrical systems is that newelectrical components begin todeteriorate as soon as they areinstalled. Whatever the loadingon a circuit, vibration, fatigueand age cause the loosening ofelectrical connections , whileenvironmental conditions canhasten their corroding. Brieflystated, all electrical connectionswill, over time, follow a pathtoward failure. If not found andrepaired, these failing connec-tions lead to faults. Fortunately, a Loose or corroded connectionincreases resistance at the con-nection and since increasedelectrical resistance results in anincrease in heat, a thermal imagewill detect the developing faultbefore it and correcting fail-ing connections before a faultoccurs averts fires as well asimpending shutdowns that canbe critical to manufacturing,commercial and institutionaloperations.

2 Such predictiveactions are important becausewhen a critical system does fail,it inevitably increases costs, Loose or corroded electrical connectionsfour decades or more ago, the principalcommercial application for thermal imaginghas been electrical system the reallocation of workers and material, reducesproductivity, threatens corporateprofitability and impacts thesafety of employees, customersand/or following discussionfocuses on using thermal imagingto troubleshoot Loose , over-tightor corroded connections in elec-trical systems by comparing thetemperatures of connectionswithin to check?Check panels with the covers off and power at ideally at least40 % of the maximum load. Measure the load, so that you canproperly evaluate your measure-ments against normal operatingconditions. Caution: only author-ized and qualified personnelusing the appropriate personalprotective equipment (PPE)should remove electrical thermal images of allconnections that have highertemperatures than other similarconnections under similar more information on Thermal Imagersgo NoteThe connections on this evaporator pumpread over 50 degrees hotter on phase forThermalImagersWhat to look for?

3 In general, look for connectionsthat are hotter than others. Theysignal high resistance possiblydue to looseness, tightness orcorrosion. connection -related hotspots usually (but not always)appear warmest at the spot ofhigh-resistance, cooling with distance from that noted, overheating connec-tions can, with additional loos-ening or corrosion, lead to afailure and should be best solution is to createa regular inspection route thatincludes all key electrical panelsand any other high-load connec-tions, such as drives, discon-nects, controls, and so on. Save athermal image of each one onthe computer and track yourmeasurements over time, usingthe software that comes with thethermal imager. That way, you llhave baseline images to compareto, that will help you determinewhether a hot spot is unusual or not, and to verify repairs represents a red alert? Equipment conditions that pose asafety risk should take the high-est repair priority. Guidelines pro-vided by the NETA (InterNationalElectrical Testing Association) saythat when the difference in tem-perature ( T) between similarcomponents under similar loadingexceeds 15 C (27 F) immediaterepairs should be same organization recom-mends the same action when the T for a component and ambientair exceeds 40 C (72 F).

4 What s the potential cost of failure?Left uncorrected, the overheatingof a Loose or corroded electricalconnection could blow a five-dollar fuse and bring down anentire production process. Then,it will probably take at least halfan hour to shut off the power, geta spare fuse from the storeroom,and replace the blown fuse. Thecost in production losses will varydepending upon the industry andThe temperature readouts show that connections on both phases A and B on this mainlighting disconnect are hot, suggesting an unbalanced process, but in many indus-tries a half hour of lost productioncan be very expensive. For exam-ple, in the steel casting industry,lost production costs from down-time have been estimated atabout US $1,000 per actionsOverheating connections shouldbe disassembled, cleaned,repaired and reassembled. If,after following this procedure, theanomaly persists, the problemmay not have been the connec-tion, although a faulty repairremains a possibility.

5 Use a multi-meter, clamp meter or a powerquality analyzer to investigateother possible reasons for theoverheating, such as overloadingor unbalance. Whenever you discover aproblem using a thermal imager,use the associated software todocument your findings in areport, including a thermal imageand a digital image of the equip-ment. It s the best way to com-municate the problems you foundand the suggested Fluke Corporation Loose or corroded electrical connectionsFluke CorporationPO Box 9090, Everett, WA USA 98206 Fluke Europe Box 1186, 5602 BD Eindhoven, The NetherlandsFor more information call:In the (800) 443-5853 or Fax (425) 446-5116In Europe/M-East/Africa (31 40) 2 675 200 or Fax (31 40) 2 675 222In Canada (800) 36-FLUKE or Fax (905) 890-6866 From other countries +1 (425) 446-5500 or Fax +1 (425) 446-5116 Web access: 2005 Fluke Corporation. All rights in 8/2005 2518864 A-EN-N Rev your worldup and imaging tipHardware used for electrical connections and contacts is oftenshiny and will reflect infrared energy from other nearby objects,which can interfere with temperature measurement and imagecapture.

6 Extremely dirty equipment can also interfere with accu-racy. To improve accuracy, wait until the equipment is de-energizedand paint dark, less-reflective spots onto the target measurementareas. Be careful not to use combustible materials such as blackpaper or plastic tape.