Siemens SIPROTEC 4 7VK61 Manual page 103

more, a general pickup indication
ratio can be set (Uph-e<(<) RESET, address 3759).
Every stage starts a time delay which is common to all phases. The expiry of the respective time delay T Uph-
e< (address 3753) or T Uph-e<< (address 3755) is signalled and usually results in the trip command
e<(<) TRIP .
Depending on the configuration of the substations, the voltage transformers are located on the busbar side or
on the outgoing feeder side. This results in a different behaviour of the undervoltage protection when the line
is de-energised. While the voltage usually remains present or reappears on the busbar side after a trip
command and opening of the circuit breaker, it becomes zero on the outgoing side. For the undervoltage
protection, this results in a pickup state being present if the voltage transformers are on the outgoing side. If
this pickup must be reset, the current can be used as an additional criterion (current supervision CURR.SUP.
Uphe<, address 3758) to achieve this result. Undervoltage will then only be detected if, together with the
undervoltage condition, the minimum current PoleOpenCurrent of the corresponding phase is also
exceeded. This condition is communicated by the central function control of the device.
The undervoltage protection phase-to-earth can be blocked via a binary input
the undervoltage protection are then automatically blocked if a voltage failure is detected ("Fuse-Failure-
Monitor", also see Section
formers is indicated (internal blocking) via the binary input
Also during a single-pole automatic reclose dead time the stages of the undervoltage protection are automati-
cally blocked in the pole open state. If necessary, the current criterion will be considered, so that the stages do
not respond to the undervoltage of the disconnected phase when voltage transformers are located on the
outgoing side. Only such stages are blocked during the single-pole dead time that can actually generate a trip
command according to their setting.
This automatic blocking function requires the condition of the system to be detected without doubt. This
means that it is only active if all three current and voltage transformers are connected.
SIPROTEC 4, 7VK61, Manual
C53000-G1176-C159-5, Edition 05.2018
Uph-e< Pickup and Uph-e<< Pickup is given. The drop-out to pickup
2.7.1 Measurement Supervision) or if the trip of the mcb of the voltage trans-
2.5 Under and over-voltage protection (optional)
Uph-e<(<) BLK . The stages of
>FAIL:Feeder VT .
Functions
Uph-
103