Monitoring The Driven Load - Siemens SINAMICS G120D Operating Instructions Manual

Advanced commissioning

8.23 Monitoring the driven load

8.23 Monitoring the driven load
In many applications, the speed and the torque of the motor can be used to determine whether
the driven load is in an impermissible operating state. The use of an appropriate monitoring
function in the converter prevents failures and damage to the machine or plant.
Examples:
• For fans or conveyor belts, an excessively low torque can mean a broken drive belt.
• For pumps, insufficient torque can indicate a leakage or dry-running.
• For extruders and mixers, an excessive torque together with low speed can indicate machine
blockage.
Functions for monitoring the driven load
The converter provides the following means to monitor the driven load via the torque of the
motor:
Monitoring the driven load with a binary signal:
268
The stall protection prevents an induction motor from stalling.
The no-load monitoring evaluates the motor current. Insufficient current indicates
that the motor and the load are no longer mechanically connected with each other.
The blocking protection triggers for a motor current that corresponds to the set
current limit coupled with motor standstill.
The torque monitoring assumes that a specific torque is associated with each speed
for pumps and fans. Insufficient torque indicates that the motor and the load are no
longer mechanically connected.
An excessive torque can indicate problems in the mechanical system of the driven
load, e.g. a mechanically blocked load.
The speed monitoring evaluates a periodic binary signal. A signal failure indicates
that the motor and the load are no longer mechanically connected with each other.
Operating Instructions, 10/2020, FW V4.7 SP13, A5E34262100B AH
Converter with the control units CU240D-2