Configuration
6.2 Overload relays in motor feeders
SIRIUS 3RU thermal overload relays / SIRIUS 3RB electronic overload relays
62 Manual, 09/2016, A5E03656507420A/RS-AB/003
Normal and heavy-duty starting
Normal starting
Selecting the right overload relay means considering the start time as well as the rated motor
current. The start time refers to the time required by the motor between switching on and
reaching its rated speed.
Table 6- 5 Normal starting
Heavy-duty starting > 10 s
Note
Overload relays with corresponding tripping classes are required to protect heavy
-duty-
starting motors (for the acceleration of large centrifuges, for example). In the case of
heavy-
duty starting, the cables and contactors also have to be dimensioned specifically on account
of the increasing thermal load.
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