KIA Niro: Power Relay Assembly (PRA)

PRA Operation Sequence

Description

The Power Relay Assembly (PRA) consists of the positive and negative main relays, pre-charge relay, pre-charge resistor and battery current sensor. It is located inside the battery pack assembly and controls the high voltage power circuit between the high voltage battery and inverter by the control signal of BMS ECU.

PRA Operation Sequence

High Voltage Battery System / Repair Procedures

Removal

Warning

• Be sure to read and follow the "General Safety Information and Caution" before doing any work related with the high voltage system. Failure to follow the safety instructions may result in serious electrical injuries.
• Be sure to read and follow the "High Voltage Shut-off Procedures" before doing any work related with the high voltage system. Failure to follow the safety instructions may result in serious electrical injuries.

1. Shut off the high voltage.

   (Refer to "High voltage Shut-off Procedures")

2. Remove the rear seat cushion.

   (Refer to Body - "Rear Seat Assembly")

3. Remove the rear door scuff trim.

   (Refer to Body - "Door Scuff Trim")

4. Remove the inlet cooling duct.

   (Refer to High Voltage Battery Cooling System - "Cooling Duct")

5. Open the floor carpet (A) to the arrow direction.

6. Remove the upper frame (A) after loosening the mounting bolts and nuts.

7. Disconnect the connectors in the illustration below.

1. Inverter power connector (+)
2. Inverter power connector (-)
3. OBC power connector (+)
4. OBC power connector (-)
5. OBC relay connector (+)
6. OBC relay connector (-)
7. PRA relay connector

8. Disconnect the battery current sensor connector (A).
9. Disconnect the high voltage power cable (+) terminal (B) and (-) terminal (C).

High voltage power cable terminal tightening nut : 7.8 - 11.8 N.m (0.8 - 1.2 kgf.m, 5.8 - 8.7 lb-ft)

10. Remove the power relay assembly (RPA) after loosening the mounting nut (A) and bolt (B).

PRA mounting nut : 7.8 - 11.8 N.m (0.8 - 1.2 kgf.m, 5.8 - 8.7 lb-ft)

Installation

Warning

• Be sure to read and follow the "General Safety Information and Caution" before doing any work related with the high voltage system. Failure to follow the safety instructions may result in serious electrical injuries.
• Be sure to read and follow the "High Voltage Shut-off Procedures" before doing any work related with the high voltage system. Failure to follow the safety instructions may result in serious electrical injuries.

1. Install the power relay assembly in the reverse order of removal.

Description

The high voltage battery system consists of the BMS ECU (Battery Management System ECU), Power
Relay Assembly (PRA), safety plug, battery temperature sensor, and battery ambient sensor.

Especially the BMS ECU controls SOC (State Of Charge), power, cell balancing, cooling and
Troubleshooting of the high voltage battery system.

The PRA includes main relays (positive, negative), pre-charge relay, pre-charge resistor and battery
current sensor.

Main Functionalities

Warning

SOC (State Of Charge): available energy of the high voltage battery

• Main High/ Sub High Voltage Battery
• Sub High Voltage Battery - Removal
• Safety Plug Description and operation
• The Power Relay Assembly

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