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2.5
27/59 Under/Over Voltage for Vx
The Feeder Automation Controller 7SC80 features a voltage input Vx which is provided in all device variants.
This voltage can be used for single-phase voltage protection.
2.5.1
Function Description
Overvoltage Protection
Single-phase overvoltage protection includes two elements. In case of a high overvoltage, tripping switch off is
performed with a short-time delay, whereas in case of less severe overvoltages, the switch off is performed with
a longer time delay. When one of the adjustable thresholds is exceeded, the 59 element picks up and trips after
an adjustable time delay has elapsed. The time delay is not dependent on the magnitude of the overvoltage.
The dropout ratio for the two overvoltage elements (= V
The following figure shows the logic diagram of the single-phase overcurrent protection function.
Figure 2-26
Logic diagram for single-phase overvoltage protection
Undervoltage Protection
Undervoltage protection includes two elements (27-1 PICKUP and 27-2 PICKUP). Therefore, tripping can
be time-graded depending on how severe voltage collapses are. Voltage thresholds and time delays can be set
individually for both elements.
The dropout ratio for the two undervoltage elements (= V
After the voltage has dropped below the pickup threshold, tripping is initiated after the time delay. As long as
the voltage remains below the dropout threshold, reclosing is blocked. Only after the fault has been cleared,
i.e. when the voltage increases above the dropout threshold, the element drops out and allows reclosing of the
circuit breaker.
SIPROTEC, 7SC80, Manual
E50417-G1140-C486-A1, Release date 12.2011
2.5 27/59 Under/Over Voltage for Vx
/V
) can be set.
dropout value
pickup value
/V
) can be set.
dropout value
pickup value
Functions
103
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