Additional Functions; Brake Energy Management; Use Of A Brake Resistor - Lenze i950 Commissioning Manual

18

Additional functions

18.1

Brake energy management

When braking electrical motors, the kinetic energy of the drive train is fed back regeneratively
to the DC bus. This energy causes a DC-bus voltage boost. If the energy fed back is too high,
the inverter reports an error.
Several different strategies can serve to avoid DC-bus overvoltage:
Stopping the deceleration ramp function generator when the active voltage threshold for
•
the brake operation is exceeded
Use of the "Inverter motor brake" function
•
Combination of the above named options
•
Details
The voltage threshold for braking operation results on the basis of the rated mains voltage set:
Rated mains voltage
230 V
400 V
480 V
Parameter
Address Name / setting range / [default setting]
0x2541:003 Brake energy management: Reduced threshold
0 ... [0] ... 100 V
18.1.1

Use of a brake resistor

For braking operation, optionally the brake chopper integrated in the inverter (brake transis-
tor) can be used.
NOTICE
Incorrect dimensioning of the brake resistor may result in the destruction of the integrated
brake chopper (brake transistor).
▶ Only connect a brake resistor complying in terms of performance to terminals R
the inverter.
▶ Avoiding thermal overload of the brake resistor.
Parameter
Address Name / setting range / [default setting]
0x2550:001 Brake resistor: Minimum resistance
• Read only: x.x Ω
0x2550:002 Brake resistor: Resistance value
0.0 ... [180.0] ... 500.0 Ω
0x2550:003 Brake resistor: Rated power
0 ... [5600] ... 800000 W
0x2550:004 Brake resistor: Maximum thermal load
0 ... [485] ... 1000000 kWs
0x2550:006 Brake resistor: Reference resistance
0 Minimum resistance
1 Resistance value
0x2550:007 Brake resistor: Thermal load
• Read only: x.x %
Voltage thresholds for braking operation
Braking operation on
DC 390 V
DC 725 V
DC 780 V
Info
The voltage threshold for the braking operation is reduced by the volt-
age value set here.
Info
Display of the minimum brake resistance value that can be used.
Resistance value of the brake resistor connected.
• The value to be entered can be obtained from the brake resistor
nameplate.
Rated power of the brake resistor connected.
• The value to be entered can be obtained from the brake resistor
nameplate.
Thermal capacity of the brake resistor connected.
• The value to be entered can be obtained from the brake resistor
nameplate.
Selection of the reference value for the brake resistor.
Display of the utilisation of the brake resistor connected.
Additional functions
Braking operation off
DC 380 V
DC 710 V
DC 765 V
and R of
B1 B2
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