ABB RELION Series, Техническое руководство

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coil sometimes is temporarily disconnected. When the coil is disconnected, the
compensated network becomes isolated and the
Characteristic angle setting must be
changed. This can be done automatically with the
RCA_CTL
input, which results in
the addition of -90° in the Characteristic angle setting.
The value (ANGLE_RCA) is available in the monitored data view.
-Uo (Polarizing quantity)
Forward area
Io (Operating quantity)
RCA = -90 ˚
Maximum torque line
Backward area
Minimum
operate current
Forward area Backward area
GUID-AA58DBE0-CBFC-4820-BA4A-195A11FE273B V1 EN
Figure 190: Definition of relay characteristic angle, RCA = -90° in an isolated
network
Characteristic angle should be set to a positive value if the operating
signal lags the polarizing signal and to a negative value if the
operating signal leads the polarizing signal.
Type of network Recommended characteristic angle
Compensated network 0°
Unearthed network -90°
In unearthed networks, when the characteristic angle is -90°, the
measured residual power is reactive (varmetric power).
The fault direction is also indicated
FAULT_DIR
(available in the monitored data
view), which indicates 0 if a fault is not detected, 1 for faults in the forward direction
and 2 for faults in the backward direction.
The direction of the fault is detected only when the correct angle calculation can be
made. If the magnitude of the operating quantity or polarizing quantity is not high
enough, the direction calculation is not reliable. Hence, the magnitude of the operating
1MRS758755 A
Section 4
Protection functions
REC615 and RER615 363
Technical Manual