ABB REC650 Applications Manual page 156

Section 6
Current protection
150
• setting RCADir to value +65 degrees, that is, the negative sequence current typically
lags the inverted negative sequence voltage for this angle during the fault
• setting ROADir to value 90 degrees
• setting LowVolt_VM to value 2%, that is, the negative sequence voltage level above
which the directional element will be enabled
• setting Operation_OC1 to Enabled
• setting PickupCurr_OC1 to value between 3-10%, (typical values)
• setting tDef_OC1 to insure proper time coordination with other ground-fault
protections installed in the vicinity of this power line
• setting DirMode_OC1 to Forward
• setting DirPrinc_OC1 to IcosPhi&V
• setting ActLowVolt1_VM to Block
DNSPTOC (46) is used in directional comparison protection scheme for the power line
protection, when communication channels to the remote end of this power line are
available. In that case, two negative sequence overcurrent steps are required - one in
forward and another in reverse direction. The OC1 stage is used to detect faults in forward
direction and the OC2 stage is used to detect faults in reverse direction.
However, the following must be noted for such application:
• setting RCADir and ROADir are applicable for both steps OC1 and OC2
• setting DirMode_OC1 must be set to Forward
• setting DirMode_OC2 must be set to Reverse
• setting PickupCurr_OC2 must be made more sensitive than pickup value of the
forward OC1 element, that is, typically 60% of PickupCurr_OC1 set pickup level in
order to insure proper operation of the directional comparison scheme during current
reversal situations
• the start signals PU_OC1 and PU_OC2 from OC1 and OC2 elements is used to send
forward and reverse signals to the remote end of the power line
• the available scheme communications function block within IED is used between the
protection function and the teleprotection communication equipment, in order to
insure proper conditioning of the above two start signals.
ActLowVolt1 and ActLowVolt2 should not be set to Memory.
1MRK 511 286-UUS A
Application manual