Hyundai NEXO Emergency Response Manual page 17

NEXO Main Systems
High-Voltage Electrical Isolation
Unlike the 12V electrical system that is grounded to the vehicle's chassis, the NEXO's high-voltage
electrical system is designed to be isolated from the vehicle.
Regulation of High-Voltage Electrical Current
Current from the high-voltage battery is
controlled by the Power Relay Assembly
(PRA), which consists of the positive and
negative main relays, a pre-charge relay,
pre-charge resistor, and the battery current
sensor. The PRA is mounted in the front side
of the high-voltage battery pack assembly
and controls the high-voltage power circuit
between the high-voltage battery and the
Electric Power Control Unit.
High-Voltage Safety System
There are multiple safety systems
incorporated into the NEXO. The system that
protects the high-voltage electrical system is
called the Battery Management System
(BMS). The BMS is located inside the Power
Relay Assembly and measures several
parameters to maintain the optimal
performance of the high-voltage battery. It
controls the battery cooling fan to ensure
proper battery operation. In addition, if a
system fault occurs, the BMS turns off the
PRA to protect the system.
PRA
BMS
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