Siemens SIMOVERT MASTERDRIVES Manual page 878

06.2005
11.7 Selection of the braking units and braking resistors
Compact PLUS
Compact and
chassis type units
Braking power
Siemens AG 6SE7087-6QX70 (Version AE)
SIMOVERT MASTERDRIVES
On Compact PLUS units, the choppers for the braking resistors are
provided in the converters and in the rectifier unit (in the case of multi-
axis drives with several inverters).
For further information regarding the selection of the braking resistor,
please refer to the MASTERDRIVES Motion Control Catalog DA65.11,
Chapter 3.
The following criteria apply to the braking resistors:
♦ The maximum braking power which occurs must be smaller than
. ⋅P . This power must not occur for more than 3 s (see technical
15
20
data).
♦ The mean braking power must be smaller than P
maximum cycle time of 90 s
The braking units for Compact and chassis type units are autonomous
components. The braking units, up to a power of P
internal braking resistor. Instead of the internal braking resistor, an
external braking resistor can be used to increase the continuous power
output. The following criteria apply to the selection process:
♦ The maximum braking power which occurs must be smaller than
. ⋅P . This power must not occur for longer than 0.4 s when there
15
20
is an internal braking resistor or 3 s when there is an external
braking resistor (see technical data).
♦ The mean braking power must be smaller than P
internal braking resistor is used or smaller than P
external braking resistor is used. The maximum cycle time is 90 s.
For further information regarding the selection of the braking resistor,
please refer to the MASTERDRIVES Motion Control Catalog DA65.11,
Chapter 3.
The braking power is calculated as follows:
= ⋅ η ⋅
P P
br Mot v Mot
⋅
M n
Mot v Mot
=
P
Mot v
9550
M Motor torque during braking in Nm
Mot v
n Motor speed in rpm
Mot
The maximum motor braking power P
beginning of deceleration when the motor is running at maximum
speed. If several inverters are operated from one rectifier unit, a check
must be made to see whether several drives can brake simultaneously.
In the event of an emergency stop, all drives may have to be shut down
at the same time.
Compendium Motion Control
η
Inv
Motor output during braking in kW
Mot v max
Engineering Information
/ . with a 4 5
20
= 20 kW, have an
20
/ 36 when an
20
/ . when an 4 5
20
generally occurs at the
11-21