Setting Notes - Siemens SIPROTEC 4 7SJ61 Manual

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Figure 2-40
2.6.3.2

Setting Notes

Elements
A warning and a tripping element can be configured. The threshold value of the tripping element 4402 Load
Jam I> is usually configured below motor startup at double motor ampere rating. Warning element 4404 I
Alarm is naturally set below the tripping element, to approx. 75% of the tripping element, with a longer delay
time (parameter 4405 ALARM DELAY). If the warning element is not required, the pickup value can be set to
its maximum value and the respective message from the buffers can be removed.
Motor Standstill and Motor Startup
Due to the threshold setting below the motor startup current, the load jam protection during motor startup
must be blocked. Via parameters 212 BkrClosed I MIN the open circuit breaker is detected during current-
flow measurement (motor standstill). In this condition the load change protection is blocked. After having
closed the circuit breaker, the blocking is maintained during motor startup by the setting 4406 T Start
Blk.. In order to avoid malfunctioning, the T Start Blk. is set to the double startup time.
SIPROTEC 4, 7SJ61, Manual
C53000-G1140-C210-6, Edition 05.2016
Logic diagram of the load jam protection
Functions
2.6 Motor Protection
109