A Genetic-Algorithm-Optimized Fractal Model to Predict the Constriction Resistance From Surface Roughness Measurements

Abstract

Abstract-The electrical contact resistance greatly influences the thermal behavior of substation connectors and other electrical equipment. During the design stage of such electrical devices it is essential to accurately predict the contact resistance to achieve an optimal thermal behavior, thus ensuring contact stability and extended service life. This paper develops a genetic algorithm (GA) approach to determine the optimal values of the parameters of a fractal model of rough surfaces to accurately predict the measured value of the surface roughness. This GA-optimized fractal model provides an accurate prediction of the contact resistance when the electrical and mechanical properties of the contacting materials, surface roughness, contact pressure and apparent area of contact are known. Experimental results corroborate the usefulness and accuracy of the proposed approach. Although the proposed model has been validated for substation connectors, it can also be applied in the design stage of many other electrical equipment.

On-line Resistance Measurement of Substation Connectors Focused on Predictive Maintenance

“…In (9) we exploit the fact that the output voltage of the Hall effect sensor is related to the current through (7). So, the phase of the output voltage of Hall effect sensor should be the same as the phase of the current in the conductor or bus bar.…”

“…The contact resistance plays a key role in the efficiency, stable performance and long-term service of electrical connections [7]. Therefore, improved electrical connections require low and stable contact resistance, otherwise overheating and service life reduction are expected [8].…”

“…To calculate the electrical contact resistance (ECR), it is necessary to subtract the bulk resistance of the connector from the total resistance of the power connector, which has been measured with the 4-wires method [7],…”

“…HallSensor Connector (7) The open loop configuration of the Hall effect sensor is selected considering that the bus bar is rigid, and the diameter of bus bar is already known.…”

“…Due to temperature cycling, the bolts tend to loose, thus increasing the resistance of the connector, although it has been reported that re-torqueing is not very useful [6], so it is better to directly replace the electrical connector before failure. It is well known that when the contact resistance starts increasing, the electrical and thermal behavior of the connector tends to deteriorate [7]. Hence, the electrical resistance of the connector is a good indicator of its condition.…”