Siemens SINAMICS DCM Manual page 544

I2t monitoring of the motor: Alarm triggering and fault triggering
The diagrams below show the time after which an alarm or fault is triggered when a new,
constant load is suddenly switched in following an extended period of preloading (> 5×T_th).
T_th = p50114 .. - thermal time constant of motor
Figure 10-70 I2t monitoring of the motor: Alarm triggering
Figure 10-71 I2t monitoring of the motor: Fault triggering
<1> ... Preloading
y ... load current/permissible continuous current (p50100 × p50113)
x ... time/thermal time constant of motor
SINAMICS DCM DC Converter
Operating Instructions, 02.2015, A5E34763375/RS-AA/001
10.19 Thermal overload protection for the DC motor (I2t monitoring of the motor)
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Descriptions of functions
545