ABB Relion 611 Series, Technical Manual

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Figure 137: Functionality of start-up supervision in the "IIt, CB" mode and the "IIt
and stall, CB" mode
The Str over delay time setting has different purposes in different modes of operation.
• In the “IIt” or “IIt & stall” modes, the aim of this setting is to check for the
completion of the motor start-up period. The purpose of this time delay setting is
to allow for short interruptions in the current without changing the state of the
MOT_START
output. In this mode of operation, the value of the setting is in the
range of around 100 milliseconds.
• In the “IIt, CB” or “IIt & stall, CB” modes, the purpose of this setting is to check
for the life of the protection scheme after the
CB_CLOSED
input has been
activated. Based on the values of the phase currents, the completion of the start-
up period cannot be judged. So in this mode of operation, the value of the time
Section 4
1MRS757454 D
Protection functions
292 611 series
Technical Manual