Setting Notes - Siemens SIPROTEC 7SC80 Series Manual

Functions
2.6 Negative Sequence Protection 46
the dropout delay time has elapsed, the pickup is reported OFF and the trip delay time is reset unless the
threshold has been exceeded again. If the threshold is exceeded again during the dropout delay time, the time
is canceled. The trip command delay time continues running. Should the threshold value be exceeded after its
expiry, the trip command is issued immediately. If the threshold value is not exceeded at this time, there will be
no reaction. If the threshold value is exceeded again after expiry of the trip-command delay time, while the
dropout delay time is still running, tripping occurs immediately.
The configured dropout times do not influence the tripping times of the inverse time elements as these depend
dynamically on the measured current value. For purposes of dropout coordination, disc emulation is used with
electro-mechanical relays.
2.6.3

Setting Notes

General
The function type has been specified during configuration of the protection functions (see Section 2.1.1.2,
address 140, 46). If only the definite time elements are desired, the address 46 should be set to Definite
Time. Selecting 46 = TOC IEC or TOC ANSI in address 140 will additionally make all parameters available
that are relevant for the inverse time characteristics. If this function is not required, then Disabled is set.
The function can be turned ON or OFF in address 4001 FCT 46.
The default pickup settings and delay settings are generally sufficient for most applications. If data is available
from the manufacturer regarding the allowable long-term load imbalance and the allowable load imbalance per
unit of time, this data should be used preferentially. It is important to note that the manufacturer's data relate to
the primary values of the machine, for example, the maximum permissible permanent inverse current is re-
ferred to the nominal machine current. For the setting values at the protection device, this information is con-
verted to the secondary inverse current. The following applies
with
I
2 perm prim
I
Nom Motor
I
CT sec
I
CT prim
110
permissible thermal inverse current of the motor
Nominal Motor Current
Secondary Nominal Current of the Current Transformer
Primary nominal current of the current transformer
SIPROTEC, 7SC80, Manual
E50417-G1140-C486-A1, Release date 12.2011