ABB RELION REB500 Technical Manual page 116

Section 5
Bay protection functions
IEC19000448 V1 EN-US
Figure 44: Directional characteristic
The function determines the power direction by measuring the phase-angle of the current in
relation to the opposite phase-to-phase voltage. Which current is compared with which
voltage can be seen from the following table:
Table 77:
Current input
I
L1
IL2
I
L3
The voltage measurement automatically compensates the group of connection of the VTs. For
example, the phase-to-phase values are calculated for Y-connected VTs (VT type UTS), while
the input voltages are used directly for delta-connected VTs (VT type UTD).
Time allowed for a signal to be received
Where directional functions are configured in both line terminals, each can send a signal from
the MeasBwd output to the Receive input of the function at the opposite end of the line (for
example, via a PLC channel) when it is measuring a fault in the reverse direction. This signal
prevents the respective directional overcurrent function from tripping, because the fault
cannot be in the zone between them. The functions therefore have to allow time, that is, the
wait time, for the signal from the opposite line terminal to be received. If none is received
within tWait, the circuit -breakers are tripped at both ends.
110
Currents, voltages used for determination of power direction
Phase-to-neutral voltage
U , U
L2 L3
U , U
L3 L1
U , U
L1 L2
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18000044-IEC19000449-1-en.vsdx
Calculated voltage
U = U - U
L2L3 L2 L3
U = U - U
L3L1 L3 L1
U = U - U
L1L2 L1 L2
Bay protection functions REB500
1MRK 505 406-UEN B
Technical manual