The automotive industry is making a transition from 14 to 42 volt electrification systems. The higher voltage poses an increase in the risk of fire to polymeric materials due to the more pronounced arcing at contacts and/or connections. Exploratory research work is being conducted to study the tracking and arc ignition properties of plastic materials when exposed to DC Voltages and DC High-Amp Arc ignition sources. This discussion will review the details and status of this work. The automotive industry is in a transitional phase at the present time and will continue to be in this mode for years to come. One of the major changes is the development of 42-volt automotive systems. The reason for this is the need to develop vehicles and systems to accommodate the ever increasing demand for increased power loads, e.g. electric power steering, entertainment systems, electromechanical breaks, electrically controlled heating and air conditioning systems. In addition, there is a push towards increasing the performance of the vehicle, emissions reduction, and better fuel economy. But along with the many advantages of going to a higher voltage, there are some hurdles to overcome. As a result of the increase in voltage to 42 volts, there are inherent safety concerns as a result of the increase in electrical potential. At 42 volts, the electrical arcing tends to be more sustaining than at the lower voltage of present day 12-volt systems. In view of the higher voltage, a potential fire hazard exists from failures of thermoplastic materials used in components such as switches and electrical connectors used in automotive applications. UL is researching properties of materials as they relate to the potential ignition of the polymeric materials when used in 42-volt automotive applications. UL is working with the United States Council for Automotive Research (USCAR) and the Motor Vehicle Fire Research Institute (MVFRI) to develop a DC Comparative Tracking Index (DC CTI) Test and a DC High-Current Arc Ignition (DC HAI) Test to evaluate materials used in automotive applications for the Big Three US Automotive Manufacturers, Daimler Chrysler, General Motors, and Ford. Two Research proposals were developed to study and evaluate the ignition properties of plastic materials for use in automotive applications. Each test proposal specifically addresses arc ignition concerns associated with the proposed increase in automobile battery voltage to 36 volts (42 volt charging). 1. DC-CTI ╚D The proposal for the development of a DC Comparative Tracking Index (DC CTI) test has been initiated and research testing has commenced. 2. DC-HAI ― A technical proposal to initiate research testing of a DC High-Current Arc Ignition (DC HAI) test has been developed.
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