Device functions
7.6 Motor protection functions
3RW44 soft starters
Manual, 03/2017, NEB535219502000/RS-AB/008
137
Prewarning limit - remaining time for tripping
A message can be issued when the set prewarning limit time, referred to the calculated time
up to tripping of the motor by the motor protection function, is reached.
Prewarning limit - motor heating
A message can be issued when the motor's set thermal prewarning limit is reached. Motor
protection is activated at 100%.
The idle time is a time defined for cooling of the motor model following an operational
shutdown, i.e. not after overload trips.
After this time, the "thermal motor model" of the motor starter is set to 50 % when motor heat
rise is still > 50 %, otherwise it is set to 0 %. Frequent starts (inching mode) are also possible
as a result. These lead to tripping where motor protection in accordance with IEC 60947 is
used, depending on the CLASS setting.
The following schematic diagram shows the cooling behavior with and without idle time.
Figure 7-11 Idle time
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