Dc Braking - Lenze i55AE125B Manual

11.4

DC braking

The "DC braking" function generates a braking torque by injecting a DC current into the motor.
The function can be used to shorten the braking of a load with high mass inertia. Another
application is holding the motor shaft either before starting or while stopping.
NOTICE
Avoid long-time activation of the "DC braking" function with a high braking current or a high
braking voltage!
Possible consequence: thermal motor overload.
▶ Only use the "DC braking" function in applications in which the load is only exceptionally
stopped.
▶ Do not activate the "DC braking" function longer than necessary.
Preconditions
The "DC braking" function is only possible if the inverter is enabled.
Details
The function can be used as follows:
1. Automatically when the motor is started.
2. Automatically when the motor is stopped.
3. Manually (via the flexible I/O configuration).
The three options can also be combined, for instance automatic DC braking when starting and
stopping the motor.
For further details and configuration examples, see the following chapter:
4Example 1: Automatic DC braking when the motor is started
4Example 2: Automatic DC braking when the motor is stopped
4Migration of Lenze Inverter Drives 8200/8400
4Activating DC braking manually
Parameter Name / value range / [default setting]
0x2B84:001 DC braking: Current
(P704.01) (DC braking: Current)
0.0 ... [0.0] ... 200.0 %
0x2B84:002 DC braking: Automatic hold time
(P704.02) (DC braking: Hold time autom.)
0.0 ... [0.0] ... 1000.0 s
0x2B84:003 DC braking: Automatic operating threshold
(P704.03) (DC braking: Threshold autom.)
0.0 ... [0.0] ... 599.0 Hz
0x2B84:004 DC braking: Demagnetization time
(P704.04) (DC braking: Demagnet. time)
0 ... [100] ... 150 %
• From version 04.00
0x2B84:005 DC braking: Default demagnetization time
(P704.05) (DC braking: Def. demag. time)
• Read only: x ms
• From version 04.00
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^ 572
Info
Braking current for DC braking.
• 100 % ≡ rated motor current
Hold time for automatic DC braking.
• The "Automatic DC braking" function is active for the time set here.
• 1000.0 = infinite
Note!
Do not set this parameter to the value "1000.0" (infinite) if the DC brak-
ing is used during the start. The "Infinite" setting can be used to lock the
rotor for an indefinite time while a stop is active. However, ensure here
that the longer DC braking does not cause a thermal overload of the
motor!
Operating threshold for automatic DC braking.
• With the setting 0, the "Automatic DC braking" function is deactiva-
In the default setting, the DC braking is activated after the standard
demagnetising time has elapsed. This parameter can be used to adapt
the time.
• 100 % ≡ Default demagnetization time
Note!
A too short demagnetising time can cause an overcurrent error!
Display of the standard demagnetising time as a setting help for the user.
• This time is calculated by the inverter:
Additional functions
^ 439
^ 440
0x6075 (P323.00)
ted.
Demagnetising time = 7 * rotor time constant
DC braking
0x2B84:005 (P704.05)
437