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  The automatic electrical connection: Questions and Answers
Open contacts on the road surface: isn't that dangerous? Multiple safety circuits prevent contacts from becoming energized, until the connection head is properly set upon the connection plate, is hooked up, the electrical connection has been tested (using low voltage), and the vehicle has been identified as a registered user.
That will never be permitted! An example: Obviously traffic regulation do not allow people to cling to the outside of a driving vehicle. But this is not an unusual attitude for garbagemen! Needless to say, the automatic electric connection has to meet the existing requirements and standards.
Open contacts on the road surface: contamination and oxidation prevent proper connections, right? Special care has to be applied to such a kind of connection. So, for instance, the electrically operated hook may allow almost unlimited pressure of the contact pins on the contact plates. Oscillating movements of the attached contact pins remove oxide coating and soiling. Before attaching the connection head, potentially existing solid items may be blown away by compressed air. Form-fit attachement of the head will be tested as well as transfer resistance and leakage current for proper operation.
What are the arguments against solutions with plugs and cables? Free hanging cables with 400V voltage on a sidewalk, posts on the roadside or at parking lots are possible sources of danger, which constitute potential risk and imply high costs for maintenance and liability. Such solutions do not really contribute to a proper cityscape. The docking procedure, alighting from the car, opening a hatch, fetching a cable, plugging in, starting the charging procedure - that are time-consuming actions, which inhibit frequent usage of a charging point.
What does the automatic connection offer? The docking procedure runs completely automatically without any move by the driver. If there is a connection plate detected underneath the vehicle and a charging strategy is already preset, the telescope arm of the automatic connection positions the connection head exactly above the connection plate on the road surface, hooks into the plate and establishes the electrical connection. The driver may already have left the car. For disconnection it's sufficient to use the central lock's remote control. The vehicle is ready to start immediately.
What are the advantages of the CarGrid idea for power grid services? The connection plate in or upon the road surface represents the least expensive connection solution. This plate is a 10 Euros device. The plate is maintenance-free and crash or vandalism proof. In car parks the plate may be mounted on the pavement without extensive concrete work. It is almost invisible and does not disturb the cityscape. The most attractive advantage for electric utilities: the high availability of vehicles in the grid to cover peak demand compared to manual solutions.
Isn't the automatic connection too expensive? While the connection plate in or on the road surface represents the most inexpensive solution for the charge infrastructure, the comfort and the availability pay a reasonable price for the connection arm, compared to a automatic gearshift against a manual gearshift, but not that expensive. Especially for the German premium car manufacturers this component is a desirable added-value.
What does "charging strategy" mean: ? The demands of the parties involved, car users and service companies, are manifold. Car users intend to be supplied with energy at most favorable conditions. They always like to keep a minimum of energy reserve, but then they like to sell as much as possible to the provider to satisfy his peak electricity demands. The service companies intend to sell electrical energy for transportation and try to avoid starting of their expensive peak power plants by using energy reserves of parked vehicles. All these concerns need to be communicated and combined to satisfy everybody.
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