2020

OU Overvoltage in the DC bus

Lenze · 9300 Servo Controller

What does 2020 mean?

The DC bus voltage has exceeded the switch-off threshold OU (e.g., 770V for <400V mains with C0173=0) as specified by parameter C0173, indicating excessive braking energy. The pulse inhibit is set, and a delay time (C0912) starts until the voltage falls below the switch-on threshold OU (e.g., 755V for <400V mains).

Additional Steps

Steps 1–2 are listed in Priority Fix.

  1. 3

    Verify the setting of parameter C0173 to ensure it matches the actual mains voltage range and operational mode (with/without brake chopper).

  2. 4

    Monitor the DC-bus voltage (C0053) at terminals +UDC/-UDC; expect values to remain below the switch-off threshold OU.

Source: Lenze 9300 Servo Controller
Open Manual (Page 456)