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Functions
2.8 27/59 Under/Over Voltage for Vx
2.8
27/59 Under/Over Voltage for Vx
The Feeder Protection and Recloser Controller 7SC80 features a voltage input Vx, which is provided in all
device variants. This voltage can be used for 1-phase voltage protection. This does not apply if the voltage
input Vx was already used as measuring input ΙA in the configuration.
Description
2.8.1
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.
[7sc80-ueberspgs-schutz-1ph-20110601, 1, en_US]
Figure 2-55
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.
1-phase undervoltage protection works without any current criterion. Please keep this in mind during parame-
terization and commissioning.
204
Logic diagram for single-phase overvoltage protection
/V
) can be set.
dropout value/
pickup value
/V
) can be set.
dropout value/
pickup value
SIPROTEC Compact, 7SC80, Manual
E50417-G1140-C486-A8, Edition 07.2017
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