Siemens SINAMICS S120 Function Manual page 342

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Basic functions

8.13 DC braking

Setting the function

DC braking is set with parameter p1231 = 4.

● Setting the braking current for DC braking with p1232[0..n]

● Setting the braking current duration for DC braking with p1233[0..n]

● Setting the start speed for DC braking with p1234[0..n]

Activating the function

The function is activated if the signal source of p1230 is set to "1". Then the following responses

are carried out:

1. First, the pulse inhibit is set for the motor de-excitation time p0347[0 ... n] until the motor is

demagnetized. The DC braking start speed parameter p1234 is not taken into account with

this activation.

2. The DC braking current p1232[0 ... n] is injected into the motor as long as a "1" signal is

available at the input of p1230. The motor can be braked down to standstill.

3. If the drive is switched off - and DC braking is activated - the drive switches itself on. DC

current is then injected into the stator windings.

Deactivating the function

If DC braking is deactivated by setting the signal source of p1230 to "0" and the ON command

is still active, then the drive returns to its selected operating mode.

Depending on the selected control mode, the following reactions are executed:

● Servo control (with encoder)

The drive returns to close-loop control after the demagnetization time has elapsed (p0347

can also be set to 0).

● Vector control (with/without encoder)

When the "flying restart" function is activated, the Motor Module is synchronized with the

motor frequency. The drive is then switched back into closed-loop controlled operation. If

the "flying restart" function is not activated, the drive can only be restarted from standstill. In

this case, for a new start you must wait until the drive has come to a standstill.

● U/f control

When the "flying restart" function is activated, the Motor Module is synchronized with the

motor frequency. The drive is then switched back to U/f control. If the "flying restart" function

is not available, the drive can only be restarted from standstill. In this case, for a new start

you must wait until the drive has come to a standstill.

Function Manual, 06/2019, 6SL3097-5AB00-0BP2

Drive functions