Siemens SINAMICS G220 - Page 681

Description of function
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Figure14-238 Flow diagram SMT
Action Converter/motor response
① 
• The OM-SMT monitors the motor temperature through the
PTC thermistor mounted on the motor side.
② 
• The electrical resistance in the PTC thermistor jumps above
the switch-o󹪜 limit.
• The OM-SMT identi󹪝es when a temperature is exceeded.
• The OM-SMT responds with fault C35550 "Motor overtem‐
perature".
• The converter activates Safe Torque O󹪜 (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.
③ Selection and deselection of
STO
• 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.
④ Signal change at ON/OFF1
from 1 to 0
• The converter is ready to start again.
⑤ Signal change at ON/OFF1
from 0 to 1
• The motor starts again.
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.
Functions
14.12Safety Integrated
SINAMICS G220 converter
Operating Instructions, 04/2024, FW V6.2, A5E51781573B AB 679