Normal And Heavy-Duty Starting - Siemens SIRIUS 3RU2 Manual

Industrial controls

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Configuration

6.2 Overload relays in motor feeders

6.2.3

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- 4

Designation

Normal starting

Heavy-duty starting

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.

Normal starting

SIRIUS Innovations - SIRIUS 3RU2 thermal overload relays / SIRIUS 3RB3 solid-state overload relays

Start time

< 10 s

> 10 s

Manual, 09/2014, A5E03656507420A/RS-AA/002

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