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Description of function
Figure 14-238
①
②
③
④
⑤
Example
SMT is used to protect against overtemperature of a motor in hazardous environments, e.g. in
the chemical industry, in paper mills, or in paint shops.
SINAMICS G220 converter
Operating Instructions, 04/2024, FW V6.2, A5E51781573B AB
Flow diagram SMT
Action
Selection and deselection of
STO
Signal change at ON/OFF1
from 1 to 0
Signal change at ON/OFF1
from 0 to 1
Converter/motor response
•
The OM-SMT monitors the motor temperature through the
PTC thermistor mounted on the motor side.
•
The electrical resistance in the PTC thermistor jumps above
the switch-off limit.
•
The OM-SMT identifies when a temperature is exceeded.
•
The OM-SMT responds with fault C35550 "Motor overtem‐
perature".
•
The converter activates Safe Torque Off (STO) as a stop re‐
sponse and signals "STO active" (r9722.0).
•
STO prevents torque-generating energy from being fed to
the motor. The motor coasts down.
•
The motor cools down.
•
The converter acknowledges the fault under the following
conditions:
– At least one minute has elapsed since the fault occurred.
– The resistance in the PTC thermistor has fallen below the
temperature limit.
•
The converter is ready to start again.
•
The motor starts again.
Functions
14.12 Safety Integrated
679
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