Firmware
≤
02.00 - DMS 2.1 EN - 03/2011
L
75
8400 motec | Software Manual
Motor control (MCTRL)
V/f characteristic control (VFCplus)
5.5.3.4
Torque limitation
The previous chapter, "
Optimising the Imax controller
", describes how the drive can be
protected from overload. During commissioning, these settings are carried out once and
remain unchanged afterwards. However, it is often necessary to limit the torque to a lower
value for plant or process reasons.
To avoid overload in the drive train, the torque in motor mode can be limited via the
nTorqueMotLimit_a
process input signal, and the torque in generator mode can be
limited via the
nTorqueGenLimit_a
process input signal:
V/f characteristic control (VFC)
The accuracy of the torque limitation is limited because the actual torque (
only calculated from the slip speed measured indirectly via the motor current.
V/f control (VFC + encoder)
The slip speed of the motor is available at the slip controller output. This leads to a high
accuracy for the actual torque (
) and the torque limitation.
Identifier
DIS code | data type
Information/possible settings
nTorqueMotLimit_a
| INT
Torque limitation in motor mode
• Scaling: 16384
≡
100 % M
max
(
)
• Setting range: 0 … +199.99 %
nTorqueGenLimit_a
| INT
Torque limitation in generator mode
• Scaling: 16384
≡
100 % M
max
(
)
• Setting range: -199.99 ... 0 %
Note!
• The actual torque (
) is directly calculated from the current slip
speed of the machine. This requires correct entry of the motor data.
• To avoid instabilities during operation with active slip compensation, the
torque limit values are internally processed as absolute values.
• If slip compensation is deactivated (
= 0), indirect torque limitation
(differential signal between apparent motor current and
nTorqueMotLimit_a
or
nTorqueGenLimit_a
). Above the no-load current of the motor, the accuracy
of the indirect torque limitation is limited.
Summary of Contents for 8400 motec Series
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