ABB Relion RES670, Техническое руководство

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measured value (DFT or RMS) do not influence the operation of directional part of
OC4PTOC.
Service values for individually measured phase currents are available on the local HMI
for OC4PTOC (51/67) function, which simplifies testing, commissioning and in
service operational checking of the function.
A harmonic restrain of the function can be chosen. A set 2nd harmonic current in
relation to the fundamental current is used.
The function can be directional.The direction of a fault is given as the current angle in
relation to the voltage angle. The fault current and fault voltage for the directional
function are dependent on the fault type. The selection of the measured value (DFT or
RMS) does not influence the operation of the directional part of OC4PTOC (51/67) .
To enable directional measurement at close-in faults, causing a low measured voltage,
the polarization voltage is a combination of the apparent voltage (85%) and a memory
voltage (15%). The following combinations are used.
Phase-phase short circuit:
_ _ ref AB A B dir AB A B
V V V I I I
= - = -
GUID-4F361BC7-6D91-47B5-8119-A27009C0AD6A V1 EN-US
(Equation 8)
_ _ ref BC B C dir BC B C
V V V I I I
= - = -
ANSIEQUATION1450 V1 EN-US
(Equation 9)
_ _ ref CA C A dir CA C A
V V V I I I
= - = -
ANSIEQUATION1451 V1 EN-US
(Equation 10)
Phase-ground short circuit:
_ _ ref A A dir A A
V V I I
= =
ANSIEQUATION1452 V1 EN-US
(Equation 11)
_ _ ref B B dir B B
V V I I
= =
ANSIEQUATION1453 V1 EN-US
(Equation 12)
_ _ ref C C dir C C
V V I I
= =
ANSIEQUATION1454 V1 EN-US
(Equation 13)
The polarizing voltage is available as long as the positive-sequence voltage exceeds
5% of the set base voltage
VBase . So the directional element can be used for all
unsymmetrical faults including close-in faults.
1MRK 511 408-UUS A
Section 8
Current protection
Phasor measurement unit RES670 2.2 ANSI 181
Technical manual