Functions
2.7 Motor Protection (Motor Starting Protection 48, Motor Restart Inhibit 66, Load Jam Protection)
SIPROTEC, 7SK80, Manual
E50417-G1140-C344-A4, Release date 08.2010
129
Emergency Start
If, for emergency reasons, motor starting that will exceed the maximum allowable rotor temperature must take
place, the motor restart inhibit signal can be removed via a binary input („>66 emer.start“), thus allowing
a new starting attempt. The thermal rotor profile, however, continues to function and the maximum allowable
rotor temperature will be exceeded. No motor shutdown will be initiated by the motor restart inhibit, but the cal-
culated excessive temperature of the rotor can be observed for risk assessment.
Blocking
If the motor restart inhibit function is blocked via binary input „>BLOCK 66“ or switched off, the thermal replica
of the rotor overtemperature, the equilibrium time T Equal and the minimum inhibit time T MIN. INHIBIT
are reset. Thus any blocking signal that is present or upcoming is disregarded.
Via another binary input („>66 RM th.repl.“) the thermal replica can be reset independently. This may be
useful for testing and commissioning, and after a power supply voltage failure.
Logic
There is no pickup annunciation for the restart inhibit and no trip log is produced. The following figure shows
the logic diagram for the restart inhibit.
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