ABB Relion 650 Series Technical Manual page 171

1MRK 506 326-UUS B
activated. Output signals PU_A, PU_B and PU_C are common for all steps. This means that the
lowest set step will initiate the activation. The PICKUP signal is common for all three phases and all
steps. It shall be noted that the selection of measured value (DFT or RMS) do not influence the
operation of directional part of OC4SPTOC (51_67).
Service value for individually measured phase currents are also available on the local HMI for
OC4SPTOC (51_67), which simplifies testing, commissioning and in service operational checking of
the function.
The function can be directional. The direction of the fault current is given as current angle in
relation to the voltage angle. The fault current and fault voltage for the directional function is
dependent of the fault type. To enable directional measurement at close in faults, causing low
measured voltage, the polarization voltage is a combination of the apparent or phase voltage
(85%) and a memory phase voltage (15%). The following combinations are used.
Phase-phase short circuit:
Phase-phase short circuit:
V = V
ref_AB
V = V
ref_BC
V = V
ref_CA
Phase-ground short circuit:
V = V
ref_A
V = V
ref_B
V = V
ref_C
Line distance protection REL650
Technical manual
-V I = I -I
A B dir_AB A B
-V I = I -I
B C dir_BC B C
–V I = I -I
C A dir_CA C A
I = I
A dir_A A
I = I
B dir_B B
I = I
C dirC C
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Section 6
Current protection
165