Siemens siprotec SJ62 User Manual page 160

SIPROTEC 4, 7SJ62/63/64 Handbuch
C53000-G1140-C147-A, Edition 07.2015
2.8 Motor Protection (Motor Starting Protection 48, Motor Restart Inhibit 66)
Based on the Long-Term Current Rating:
For ratios deviating from nominal conditions, the motor tripping time changes:
At 80% of nominal voltage (which corresponds to 80% of nominal starting current), the
tripping time is:
After the delay time 4104 LOCK ROTOR TIME has elapsed, the locked rotor binary
input becomes effective and initiates a tripping signal. If the locked rotor time is set just
long enough that during normal startup the binary input „>Rotor locked" (FNo.
6805) is reliably reset during the delay time LOCK ROTOR TIME, faster tripping will be
available during motor starting under locked rotor conditions.
Note
Overload protection characteristic curves are also effective during motor starting con-
ditions. However, thermal profile during motor starting is constant. The setting at
address I MOTOR START (1107) limits the operating range of the overload protection
with regard to larger currents.
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