On the other hand, if the Vdc_max controller increases the output frequency (e.g. for a steady-state regenerative load), then the Vdc_max controller is disabled by an internal drive inverter monitoring function and warning A0910 is output. If the regenerative load continues, the drive inverter is protected using fault F0002.
In addition to controlling the DC link, the Vdc_max controller supports the stabilizing processes of the speed at the end of an acceleration phase. This is especially the case if there is an overshoot and the motor therefore briefly goes into regenerative operation (damping effect).
NOTE
If the DC link voltage exceeds the power-on threshold r1242 (switch-on level of Vdc_max.) of the Vdc_max controller in the "Ready" state, then the Vdc_max controller is de-activated and warning A0910 is output.
Cause: The line supply voltage does not match the application situation.
Remedy: Refer to parameters P1254 and P0210.
If, in the "Run" state, the DC link voltage exceeds the power-on threshold r1242 and if the Vdc_max controller output is limited by parameter P1253 for approx. 200 ms, then the Vdc_max controller is de-activated and warning A0910 and, where relevant, fault F0002 are output.
Cause: Line supply voltage P0210 or ramp-down time P1121 too low The moment of inertia of the driven load is too high
Remedy: Refer to parameters P1254, P0210, P1121
The Vdc_max switch-in threshold VDC_max depends on P1254 VDC_max(P1254 = 0) ≠ VDC_max(P1254 ≠ 0)
a)Auto-detect function enabled (P1254 = 1):
-VDC_max (P1254 = 1) is automatically calculated when the drive inverter runs-up, i.e. after the line supply voltage has been connected
-Using the auto-detect function, the VDC-Compthreshold automatically adapts itself to the line supply voltage at the particular installation location.
b)Auto-detect function disabled (P1254 = 0):
-UDC _ max = 1.15 ⋅ 
2 ⋅P0210
-The VDC-Compthreshold is immediately re-calculated after entering P0210
-P0210 must be adapted to the particular installation location.
