The implementation of Electric Vehicle (EV) charging stations has been growing for multiple years and with the advent of more available product manufacturers as well as the potential local and state incentives, interest has been increasing. This article serves to provide some of the details that need to be considered when considering design and installation of EV stations.
EV Stations generally are rated for 240V, 1 Phase AC supply source, which rectifies the voltage to a DC source, and a DC converter to boost the DC voltage to a utilization level suitable for the vehicle or connector being used. There are AC and DC filters in typical chargers that also prevent electrical noise and distortion from the rectification process from being passed through to the vehicles. Initially, there was a large disparity in types of connectors required for different vehicles, but this has been standardized by the SAE J1722 Connector Standard.
When selecting charging stations additional consideration must be given charging times and the limitation of vehicle manufacturer maximum charging acceptance rates. Charger stations typically range from 20 Ampere to 80 Ampere AC input rated stations and selection of the input affects the charging time differently. For instance, if you are designing for street parking stations you may want to design for short term charging durations than if you are designing for a parking building, parking lot, or a home where the vehicle would be parked for longer durations or overnight. These charging stations are classified as Level 1 or 2 stations, where Level 1 are typically designated for long term parking (lower input amperage) and Level 2 are typically designated for shorter term parking (higher input amperage).
Some of the other considerations when selecting the charging stations are the equipment options. Most manufacturer’s offer variations on their standard offering that include dual charging ports that can accommodate different vehicle plugs, cable cradle or retractable cable management systems, station locking mechanisms for security, and access control stations (also for security). There are also installation options for pedestal mounted as well as wall mounted stations.
Additionally, most manufacturer’s provide options for a complete DDC (Direct Digital Control) where each charger is provided with a communication card and can be integrated with a Building Management System (BMS) or SCADA system. This provides options to make the stations accessible during certain hours, monitor usage and display the information at a kiosk, and implement station metering for user payment. An important consideration when implementing a network connected installation is that most manufacturers require an annual maintenance cost to maintain the networking functions.
An important consideration outside of the charging station selection is the provision for source power for the stations. Typically, the source would originate in a building and the physical separation from an electrical room can be a large part of the implementation cost. In most cases, running feeders to the stations will involve a run inside the building as well as an underground component that will require trenching and restoration. If multiple stations are being considered, sometimes locating a panel-board closer to the chargers should be considered and planned for, where a single long run can be done with multiple shorter runs to the charging stations. However, physical space must be considered for this panel-board. This distance in the feeder run must be considered when selecting the input voltage of the charging stations as well. If the run is considerable, then 480V may be more feasible in order to reduce voltage drop to the stations.
New Jersey has a Pay$ to Plug In program where they provide incentives for installing charging stations. The program is maintained by the NJ DEP Bureau of Mobile Sources. Some key components of the program is that it is limited to between 2 and 20 stations, approval must be provided before any work commences or equipment is purchased, stations require bollards for protection, stations must be network connected to enable data reporting requirements. The program provides incentives up to $4,000 per station for Level 2 chargers.
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