Reducing electrical contact resistance at highly loaded copper conductor using nickel and silver coating

Electric motor used in an electrical vehicle commonly operated under high direct current of several hundred amperes. In such condition conductor contacts are very critical. Bad contacts may result in losses, overheating and disturb the operation of the motor. The improvement of contact can be achieved by reducing the contact resistance. This paper reports investigation results on the effects of silver and nickel coating on the contact surface in improving the contact performance in copper conductors. The effect of the pressure on the contact was also investigated. The current used in the investigation is direct current with magnitude of up to 350 A. The measured parameter was contact resistance. Contact resistance was measured using micro ohmmeter. The investigation results indicated significant improvement of conductor contact performance by applying the silver and nickel coating on the contact surfaces. The contact resistance reduced from 10.6 μΩ for uncoated contact to 9.5 μΩ for nickel coated and to 5 μΩ for silver coated contact.