Setting Notes - Siemens Siprotec 7UM611 Manual

2 Functions
Figure 2-13
The reduction of the current pickup threshold on decreasing voltage (control voltage
allocation) is performed phase in accordance with Table 2-3.
2.8.2

Setting Notes

Inverse overcurrent time protection is only effective and available if address 114 O/C
General
PROT. Ip was set to with IEC or with ANSI. If the function is not needed it is set
to Disabled.
The address 1401 O/C Ip serves to switch the function ON or OFF or to block only
Ip Overcurrent
the trip command (Block relay). It must be noted that, for the inverse overcurrent
Stage
time protection, a safety factor of about 1.1 has been included between the pick-up
value and the setting value. This means that a pickup will only occur if a current of
about 1.1 times of the setting value is present. The dropout occurs as soon as the
value falls below 95% of the pickup value.
56
Logic Diagram of the Voltage Restraint Inverse Time Overcurrent Protection
7UM61 Manual
C53000-G1176-C127-3