ABB RELION 620 Series Technical Manual page 909

1MRS757644 F
6.5.6
620 series
Technical Manual
Three phase network
VT
REF 615
GUID-FA649B6A-B51E-47E2-8E37-EBA9CDEB2BF5 V2 EN
Figure 471: Fault in a circuit from the voltage transformer to the protection relay
A fuse failure occurs due to blown fuses, broken wires or intended substation
operations. The negative sequence component-based function can be used to detect
different types of single-phase or two-phase fuse failures. However, at least one of the
three circuits from the voltage transformers must be intact. The supporting delta-based
function can also detect a fuse failure due to three-phase interruptions.
In the negative sequence component-based part of the function, a fuse failure is
detected by comparing the calculated value of the negative sequence component
voltage to the negative sequence component current. The sequence entities are
calculated from the measured current and voltage data for all three phases. The
purpose of this function is to block voltage-dependent functions when a fuse failure is
detected. Since the voltage dependence differs between these functions, SEQSPVC
has two outputs for this purpose.
Signals
Table 868: SEQSPVC Input signals
Name Type
I_A SIGNAL
I_B SIGNAL
I_C SIGNAL
I SIGNAL
2
U_A_AB SIGNAL
U_B_BC SIGNAL
U_C_CA SIGNAL
U SIGNAL
2
BLOCK BOOLEAN
Table continues on next page
Fault in a measuring
circuit between
voltage transformer
and protection relay
e.g. blown fuse
Default Description
0 Phase A current
0 Phase B current
0 Phase C current
0 Negative sequence current
0 Phase A voltage
0 Phase B voltage
0 Phase C voltage
0 Negative phase sequence voltage
0=False Block of function
Section 6
Supervision functions
903