Cause : Brake resistor comes when the braking resistor circuit, such as an open circuit, short circuit, or incorrect wiring. This fault can also arise from incorrect parameter settings or problems with the brake chopper (the internal component controlling the brake resistor).

The A791 fault code in your ABB ACS560 drive indicates a brake resistor fault. This fault signifies that the braking resistor connected to the drive is faulty or incorrect brake resistor wiring.