Siemens 420 manual Electronic brakes, DC braking

3 Functions Issue 07/04

3.14Electronic brakes

MICROMASTER 420 has 2 electronic brakes:

DC braking	(refer to Section 3.14.1)
Compound braking	(refer to Section 3.14.2)

These brakes can actively brake the drive and avoid a possible DC link overvoltage condition. An inter-dependency as shown in Fig. 3-50 is present.

DC braking P1233 > 0

?

yes

DC braking

enabled

no	Compound		no
	braking
	P1236 > 0
	?
		yes
	Compound braking
	enabled

disabled

	Fig. 3-50	Inter-dependency of the electronic brakes
3.14.1	DC braking
	Parameter range:		P1230, P1232, P1233
			r0053 Bit00
	Warnings		-
	Faults		-
	Function chart number:		-

The drive decelerates along a parameterized braking ramp if an OFF1 / OFF3 command is output. A "flat" ramp must be selected so that the drive inverter is not tripped (shutdown) due to the high regenerative energy which would cause a DC link overvoltage condition. The DC brake should be activated while the OFF1 / OFF3 command is present if the drive is to be braked faster. For DC braking, instead of continually reducing the output frequency / voltage during the OFF1 / OFF3 phase, a DC voltage / current is input (refer to sequence a).

The drive can be brought to a standstill in the shortest time using DC current braking (DC brake). DC braking is selected as follows:

After OFF1 or OFF3 (the DC brake is released via P1233)	Sequence ➀
Directly selected using BICO parameter P1230	Sequence ➁

For DC braking, a DC current is impressed in the stator winding which results in a significant braking torque for an induction motor. The magnitude, duration and frequency at which braking starts can be set for the braking current and therefore braking torque by setting the appropriate parameters.

MICROMASTER 420	Operating Instructions
122	6SE6400-5AA00-0BP0