Siemens siprotec 7SA6 User Manual page 392

Functions
Freely Selectable
Single–phase
Voltage
6-210
has been signalled via the binary input "!)$,/ )HHGHU 97" (internal signal "internal
blocking").
The stages of the zero sequence voltage protection are automatically blocked (with
the internal automatic reclosure function) during single-pole automatic reclose dead
time to avoid pick-up with the false zero sequence values arising during this state. If
the device operates with an external automatic reclosure function or if single-pole
tripping can be triggered by a different protection system (operating in parallel), the
overvoltage protection for the zero sequence system must be blocked via a binary
input during single-pole tripping.
According to Figure 6-107 the device calculates the voltage to be monitored:
3⋅U = U + U + U
0 L1 L2
This applies if no suitable voltage is connected to the fourth measuring input U
However, if the displacement voltage U
connected to the fourth measuring input U
entered during configuration the device will automatically use this voltage and
calculate the triple zero sequence voltage.
= 8SK  8GHOWD ⋅ U
3⋅U
0
As the voltage transformation of the voltage transformer set is usually
⁄ ⁄
U U U
Nprim Nsek
----------------- - --------------- - --------------- -
3 3
the factor is 8SK  8GHOWD = 3/√3 = √3 ≈ . For more details see Power System
Data 1 in Section 6.1.1, margin heading "Voltage Transformer Connection", address
.
U U
L1-E
Ph–E
U
L2-E
3U
U
0
L3-E
internal blocking
≥1
FNo 10203
>3U0>(>) BLK
Figure 6-107 Logic diagram of the overvoltage protection for zero sequence voltage
As the zero sequence voltage stages operate separately and independent from the
other protective overvoltage functions they can be used for any other single–phase
voltage. Therefore the fourth voltage input U
accordingly. (also see Section 6.1.1 in "Voltage Transformer Connection").
The same features apply as for the use of the zero sequence voltage protection, i.e.
blocking via a binary input ">8! ! %/.", when the asymmetrical "Fuse–Failure–
Monitor" picks up during trip of the mcb for the voltage transformers, and during the
single-pole dead time before automatic reclosure.
.
L3
of the voltage transformer set is directly
en
of the device and this information was
4
.
4
Nsek
3
"&!! "V3
U>
"&!( "V33ÃS@T@U
U>>
"&!# "V33
4
T 0
UÃ"V3 "&!"
≥1
UÃ"V33 "&!$
T 0
of the device must be assigned
C53000-G1176-C133-1
.
4
FNo 10270
3U0> Pickup
FNo 10272
T 3U0> TimeOut
FNo 10274
3U0>(>) TRIP
FNo 10273
T 3U0>> TimeOut
FNo 10271
3U0>> Pickup
7SA6 Manual