ABB RELION Series Technical Manual page 372

Section 4
Protection functions
366
"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
Residual Power start value of 1.0 × Pn corresponds then 1.0 × 20.000 kV × 100 A =
2000kW in primary
If "Calculated Uo" is selected for the Uo signal Sel setting, the
nominal value for residual voltage Un is always phase-to-phase
voltage. Thus, the valid maximum setting for residual Voltage start
value is 0.577 × Un, which corresponds to full phase-to-earth voltage
in primary.
Timer
Once activated, Timer activates the START output. Depending on the value of the
Operating curve type setting, the time characteristics are according to DT or
wattmetric IDMT. When the operation timer has reached the value of Operate delay
time in the DT mode or the maximum value defined by the inverse time curve, the
OPERATE output is activated. If a drop-off situation happens, that is, a fault suddenly
disappears before the operating delay is exceeded, the timer reset state is activated.
1MRS758755 A
REC615 and RER615
Technical Manual