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SUPERCHARGER SAFETY MECHANISMS T _ rS L n Internal External Contactors Contactors Fuse -------- , ----- Charger B To Vehicle A modules ' r-�--► .�► modules er .!—. To Vehicle B DC Output Overcurrent Protection The Supercharger Cabinet monitors the DC output for overcurrent. In the event of overcurrent, firmware will shut down the chargers and open DC output contactors. As a backup, the Cabinet contains hardware enable lines to perform the same functions. The Supercharger Charge Post also monitors DC output current with current transducers. If any conductor exceeds a preset limit, the Charge Post Control Board will trigger a fallback mode with reduced current. Low-Voltage DC Switch and Fuses The Supercharger Cabinet's power conversion is controlled by low-voltage DC electronics powered by AC through a switch between the main AC feed and the low-voltage DC transformer. This switch opens in the event of overcurrent, or can be opened manually. When the switch opens or AC power is not present, it cuts power delivery to the low-voltage DC electronics, which shuts down charging functionality by disabling digital communication between the Supercharger and the vehicle. Fuses protect against overcurrent on the low-voltage DC lines. High Voltage Interlock Loop (HVIL) Switch When the front door or rear access panel of the Supercharger Cabinet is opened, HVIL loop switches interrupt a hardware interlock line to the Cabinet control boards, charger modules, and the DC contactors. The DC output contactors are prevented from closing when the HVIL switches are open. A microcontroller and CPLD in the Cabinet can also break the HVIL loop. Fan and Coolant Pump The Cabinet monitors coolant and ambient temperature and sets the coolant pump duty cycle and fan speed to ensure that the electronics remain in the operable temperature range. Gateway Tesla's Supercharger Service department continuously monitors the health of all equipment in the field using diagnostics communicated via a cellular(3G or 4G) gateway connection. Automated scripts flag and prioritize critical issues, and regionally distributed Supercharger Service technicians address all issues as quickly as possible. Cabinet Control Boards Two control boards, a master and a slave, control the operation of the charger modules allocated to each of up to two connected vehicles. The control boards monitor the various safety mechanisms and control the power shut-down procedure in the case of fault. Charge Post Control Board The Charge Post controller monitors current flow within the Charge Post, and also serves as an adapter between the Cabinet communications protocol and the regional vehicle charging standards. Often, DC current is split down parallel Rev. 1.0, September 2018 CONFIDENTIAL INFORMATION-SHARED UNDER NDA ONLY Page 4 of 8