Siemens SIPROTEC 7SD610 Manual page 155

Overvoltage positive sequence system U
The device calculates the positive sequence system according to its defining equation
1
U = / ·(U
1 3 L1
j120°
where a = e
The resulting positive sequence voltage is fed to the two threshold stages U1> (address 3732) and U1>> (ad-
dress 3734) (see Figure 2-57). Combined with the associated time delays T U1> (address 3733) and T U1>>
(address 3735), these stages form a two-stage overvoltage protection based on the positive sequence system.
Here too, the drop-out to pickup ratio can be set.
The overvoltage protection for the positive sequence system can also be blocked via a binary input „>U1>(>)
BLK".
Figure 2-57 Logic diagram of the overvoltage protection for the positive sequence voltage system
SIPROTEC, 7SD610, Manual
C53000-G1176-C145-6, Release date 02.2011
1
2
+ a·U + a ·U )
L2 L3
.
2.11 Undervoltage and Overvoltage Protection (optional)
Functions
155