Lenze 8400 - Manual (Page 278)

5 Motor control (MCTRL)
5.13 Braking operation/brake energy management
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Lenze · 8400 protec HighLine · Reference manual · DMS 3.0 EN · 03/2013 · TD05
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For sensorless vector control (SLVC) and servo control (SC):
• Set reduced brake chopper threshold ( C00174 ) to approx. 70 V.
• Set additive speed ( C00987 ) to 2 ... 4-fold rated slip speed.
• Adapt the deceleration ramp so that the deceleration time is slightly below (10 ... 30 %)
the deceleration time that can be realised with the inverter motor brake.
5.13.3 Avoiding thermal overload of the brake resistor
• Parameterisation of an error response in C00574 and evaluation of the parameterised error
message within the application or within the machine control system.
• See chapter entitled " Brake resistor monitoring (I2xt) ". ( 286)
• External interconnection using the thermal contact on the brake resistor (e.g. supply
interruption via the mains contactor and activation of the mechanical brakes).
5.13.4 Control of multiple internal brake choppers in the DC-bus system
This function extension is available from version 12.00.00!
If an additional control signal is used, all internal brake choppers can be used in the DC-bus system
to dissipate regenerative energy ("Master-slave operation").
Functional principle
One of the controllers of the DC-bus system is assigned the role of the "brake chopper master".
• For logical reasons, the "brake chopper master" should be the most powerful controller.
• The "brake chopper master" controls its internal brake chopper via the DC-bus voltage as before.
In addition, the "brake chopper master" transmits the bBrakeChopperActive status signal of its
internal brake chopper control to the other controllers of the DC-bus system via fieldbus or
digital output.
All other controllers of the DC-bus system are "brake chopper slaves".

Stop!
The integration of external brake choppers (e.g. brake chopper 9352) in the above-
described "Master-slave operation" is not permissible since the voltage levels for the
input and output of the external brake chopper are not suitable for the brake transistor
control or, more precisely, for the output of the state of the brake transistor.
If the internal brake choppers of the DC-bus system are not sufficient, they should be
replaced by an external brake chopper. It can be synchronised with other external brake
choppers, if need be, so that simultaneous switch-on of all external brake choppers is
ensured.

Note!
For trouble-free operation, the setting of the mains voltage in C00173 must be identical
for all controllers of the DC-bus system since this setting also influences the brake
chopper threshold for switching on the brake chopper.