Siemens SINAMICS V20 Operating Instructions Manual page 98

Commissioning via the built-in BOP
5.6 Function commissioning
Setting parameters
Parameter Function
P1237 Dynamic braking
P1240[0...2] Configuration of Vdc controller
P1254 Auto detect Vdc switch-on lev-
els
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.
98
Duty cycle t
ON
5%
10%
20%
50%
100%
Setting
This parameter defines the rated duty cycle of the braking resistor
(chopper resistor). Dynamic braking is active when the function is ena-
bled and DC-link voltage exceeds the dynamic 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 disabled) to acti-
vate 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 appli-
cable for frame size D inverters.
WARNING
(s) t (s)
OFF
12.0 228.0
12.6 114.0
14.2 57.0
22.8 22.8
Infinite
t (s)
cycle
240.0
126.6
71.2
45.6
0 Infinite
SINAMICS V20 Inverter
Operating Instructions, 11/2016, A5E34559884-006
P
DB
0.05
0.10
0.20
0.50
1.00