Siemens SINAMICS V20 Operating Instructions Manual page 97

Setting parameters
Parameter Function
P1237 Dynamic braking
P1240[0...2] Configuration of Vdc controller
P1254 Auto detect Vdc switch-on levels
Risks with the use of inappropriate braking resistors
Braking resistors, which are to be mounted on the inverter, must be designed so that they
can tolerate the power dissipated. If an unsuitable braking resistor is used, there is a
danger of fire and the associated inverter will be significantly damaged.
SINAMICS V20 Inverter
Operating Instructions, 09/2014, A5E34559884
WARNING
Setting
This parameter defines the rated duty cycle of the braking
resistor (chopper resistor). Dynamic braking is active when
the function is enabled and DC-link voltage exceeds the dy-
namic braking switch-on level.
= 0: Disabled (factory default)
= 1: 5% duty cycle
= 2: 10% duty cycle
= 3: 20% duty cycle
= 4: 50% duty cycle
= 5: 100% duty cycle
Note: This parameter is only applicable for inverters of frame
size D. For frame sizes A to C, the duty cycle of the braking
resistor can be selected with the dynamic braking module.
This parameter enables / disables Vdc controller.
= 0: Vdc controller disabled
Note: This parameter must be set to 0 (Vdc controller disa-
bled) to activate the dynamic braking.
This parameter enables / disables auto-detection of switch-on
levels for Vdc_max controller.
= 0: Disabled
= 1: Enabled (factory default)
It is recommended to set P1254 = 1 (auto detection of Vdc
switch-on levels enabled). Note that auto detection only works
when the inverter has been in standby for over 20s. When
P1240 = 0, P1254 is only applicable for frame size D invert-
ers.
Commissioning
5.6 Function commissioning
97