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Sample Thermal Analysis of an Electrical Component with a Resistive Fault

Jack M. Kleinfeld, P.E.
Kleinfeld Technical Services, Inc.


This sample analysis demostrates the ability of FEA to provide insight to practicing thermographers by taking externally available information and calculating what is happening inside. In this case a resistive fault at the knife contact was modeled. The analysis provides a relationship between the magnitude of the fault, the temperatures observed on the outside of the component, and the temperatures achieved on the inside of the component. As modeled, the plexiglass surrounding only heats up a small amount. The large copper conductors, however get quite hot both inside and outside. Because they have low emissivity, measuring them would be difficult. The internal temperature at the fault reaches about 200F. The exposed copper reaches about 190F maximum. The plexiglass does not exceed 90F, except where it was modeled as in direct contact with the copper.

Physical Model

Contactors are copper. Baseplate is steel. Pivot under lower contact is ceramic porcelain. Covering box, shown as transparent, is plexiglass. Dimensions shown are in inches.

Model Views
Overall Isometric
Closeup of Resistive Contact

Thermal Results

Isometric View

Front View

Top View

Cross Section View


FEA allows a better understanding of the critical temepratures that may be achieved in areas where they cannot be measured. This simplified sample analysis shows how FEA can supplement and extend the utility of IR thermography, however it is ONLY A SAMPLE!! do not rely on these results.

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2001 Kleinfeld Technical Services, Inc.