ABB Relion REC615, Техническое руководство

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current channel Configuration > Analog inputs > Current (Io, CT). If "Calculated
Io" is selected, the nominal values for primary and secondary are obtained from
the current transformer ratio entered for phase current channels Configuration >
Analog inputs > Current (3I, CT).
For residual voltage Uo, if "Measured Uo" is selected, the nominal values for primary
and secondary are obtained from the voltage transformer ratio entered for residual
voltage channel Configuration > Analog inputs > Voltage (Uo, VT). If "Calculated
Uo" is selected, the nominal values for primary and secondary are obtained from
the voltage transformer ratio entered for phase voltage channels Configuration >
Analog inputs > Voltage (3U, VT).
Calculated Uo requires that all three phase-to-earth voltages are
connected to the protection relay. Uo cannot be calculated from the
phase-to-phase voltages.
As nominal power is the result of the multiplication of the nominal current and the
nominal voltage Pn = Un × In, the calculation of the setting value for
Power start
value (×Pn) depends on whether Io and Uo are measured or calculated from the
phase quantities.
Table 396: Measured and calculated Io and Uo
Measured Io Calculated Io
Measured Uo Pn = (Uo, VT) × (Io, CT) Pn = (Uo, VT) × (3I, CT)
Calculated Uo Pn = (3U, VT) × (Io, CT) Pn = (3U, VT) × (3I, CT)
Example 1. Io is measured with cable core CT (100/1A) and Uo is measured
from open delta-connected VTs (20/sqrt(3) kV:100/sqrt(3) V:100/3 V). In this case,
"Measured Io" and "Measured Uo" are selected. The nominal values for residual
current and residual voltage are obtained from CT and VT ratios.
Residual current Io: Configuration > Analog inputs > Current (Io, CT): 100 A:1 A
Residual voltage Uo: Configuration > Analog inputs > Current (Uo, VT): 11.547
kV:100 V
Residual Current start value of 1.0 × In corresponds then 1.0 × 100 A = 100 A in
primary
Residual Voltage start value of 1.0 × Un corresponds then 1.0 × 11.547 kV = 11.547 kV
in primary
Residual Power start value of 1.0 × Pn corresponds then 1.0 × 11.547 kV × 100 A =
1154.7kW in primary
Example 2. Both Io and Uo are calculated from phase quantities. Phase CT-ratio
is 100:1 A and Phase VT-ratio 20/sqrt(3) kV:100/sqrt(3) V. In this case "Calculated
Io" and "Calculated Uo" are selected. The nominal values for residual current and
residual voltage are obtained from CT and VT ratios entered in:
Residual current Io: Configuration > Analog inputs > Current (3I, CT): 100 A:1 A
Residual voltage Uo: Configuration > Analog inputs > Current (3U, VT): 20.000
kV:100 V
Residual Current start value of 1.0 × In corresponds then 1.0 × 100 A = 100 A in
primary
Residual Voltage start value of 1.0 × Un corresponds then 1.0 × 20.000 kV = 20.000 kV
in primary
1MRS758755 C Protection functions
REC615 & RER615
Technical Manual
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