ABB RELION REB500 Technical Manual page 109

1MRK 505 406-UEN B
IEC19000446 V1 EN-US
Figure 42: 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 74:
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).
Delay
The delay enables the protection to be graded with other time-overcurrent relays to achieve
discrimination. Its setting is thus chosen in relation to the timer settings of upstream and
down-stream protective devices. The zone of protection covered by the overcurrent protection
extends to the next overcurrent protection device.
Should in the event of a fault in the next downstream zone, the protection for that zone fail,
this protection function takes over after the time set for
role.
Bay protection functions REB500
Technical manual
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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18000041-IEC19000446-1-en.vsdx
Calculated voltage
U = U - U
L2L3 L2 L3
U = U - U
L3L1 L3 L1
U = U - U
L1L2 L1 L2
Delay and clears the fault in a backup
Section 5
Bay protection functions
103