Undervoltage Protection 27 Of Side 2 - Siemens 7SC80 Manual

The pickup voltages and time delays can also be set phase-specifically.
The following figure shows the logic diagram of the Overvoltage protection 59 of side 2 function.
The logic diagram also applies to setting the phase-specific overvoltage protection (Vphph selective or
Vph-n selective). The threshold values and time delays have to be replaced with the phase-specific
values.
[lo_OVPSide2, 1, en_US]
Figure 2-142
2.30.2.4

Undervoltage Protection 27 of Side 2

Function
The Undervoltage protection 27 of side 2 function consists of two definite time elements (27-1 PICKUP
S2 and 27-2 PICKUP S2). Therefore, tripping can be time-coordinated depending on how severe voltage
collapses are. Voltage thresholds and time delays can be set individually for both elements.
The pickup voltages and time delays can also be set phase-specifically.
The dropout ratio for the two undervoltage elements (= V
The Undervoltage protection 27 of Side 2 function works in an expanded frequency range. The RMS value of
the positive voltage component is considered too small when the frequency deviates considerably so that the
device tends to overfunction.
Figure 2-143 shows a typical voltage profile during a fault for source side connection of the voltage trans-
formers. Because full voltage is present after the circuit breaker has been opened, current supervision CS
described above is not necessary in this case. After the voltage has dropped below the pickup setting, tripping
is initiated after time delay 27-1 DELAY S2. As long as the voltage remains below the dropout setting,
reclosing is blocked. Only after the fault has been cleared, i.e. when the voltage increases above the dropout
level, the element drops out and allows reclosing of the circuit breaker.
SIPROTEC Compact, 7SC80, Manual
E50417-G1140-C486-A8, Edition 07.2017
Logic Diagram of the Overvoltage Protection 59 of Side 2 Function
2.30 Additional Applications with 6 Voltage Inputs
/V ) can be set.
dropout value pickup value
Functions
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