Load Torque Monitoring (System Protection) - Siemens SINAMICS G120 CU240B-2 Operating Instructions Manual

7.7.6

Load torque monitoring (system protection)

In many applications, it is advisable to monitor the motor torque:
● Applications where the load speed can be indirectly monitored by means of the load
● Applications that are to be protected against overload or locking (e.g. extruders or
● Applications in which no-load operation of the motor represents an impermissible
Load torque monitoring functions
The inverter monitors the torque of the motor in different ways:
1. No-load monitoring:
2. Blocking protection:
3. Stall protection:
4. Speed-dependent torque monitoring
Table 7- 21
Parameter
No-load monitoring
P2179
P2180
Blocking protection
P2177
Stall protection
P2178
P1745
Inverter with CU240B-2 and CU240E-2 Control Units
Operating Instructions, 07/2010, FW 4.3.2, A5E02299792B AA
torque. For example, in fans and conveyor belts too low a torque indicates that the drive
belt is torn.
mixers).
situation (e.g. pumps).
The inverter generates a message if the motor torque is too low.
The inverter generates a message if the motor speed cannot match the speed setpoint
despite maximum torque.
The inverter generates a message if the inverter control has lost the orientation of the
motor.
The inverter measures the actual torque and compares it with a parameterized
speed/torque characteristic.
Parameterizing the monitoring functions
Description
Current limit for no-load detection
If the inverter current is below this value, the message "no load" is output.
Delay time for the "no load" message
Delay time for the "motor locked" message
Delay time for the "motor stalled" message
Deviation of the setpoint from the actual value of the motor flux as of which the
"motor stalled" message is generated
This parameter is only evaluated as part of encoderless vector control.
Functions
7.7 Protection functions
181