ABB 615 series Technical Manual page 334

Section 4
Protection functions
328
of 1.0 × In corresponds to 1.0 * 100 A = 100 A in the primary. The Voltage pickup value
of 1.0 × Vn corresponds to 1.0 * 11.547 kV = 11.547 kV in the primary.
Example 2: Both I0 and V0 are calculated from the phase quantities. Phase CT-ratio is
100 : 1 A and phase VT-ratio is 20/sqrt(3) kV : 100/sqrt(3) V. In this case, "Calculated I0"
and "Calculated V0" are selected. The nominal values for residual current and residual
voltage are obtained from CT and VT ratios entered in Residual current I0:
Configuration/Analog inputs/Current (3I,CT): 100 A : 1 A. The residual voltage V0:
Configuration/Analog inputs/Voltage (3V,VT): 20.000 kV : 100 V. The Pickup value
of 1.0 × In corresponds to 1.0 * 100 A = 100 A in the primary. The Voltage pickup value
of 1.0 × Vn corresponds to 1.0 * 20.000 kV = 20.000 kV in the primary.
If "Calculated V0" is selected, the residual voltage nominal value is
always phase-to-phase voltage. Thus, the valid maximum setting for
residual Voltage pickup value is 0.577 x Vn. The calculated V0 requires
that all the three phase-to-ground voltages are connected to the protection
relay. V0 cannot be calculated from the phase-to-phase voltages.
If the Enable voltage limit setting is set to "True", the magnitude of the
polarizing quantity is checked even if the Directional mode was set to
"Non-directional" or Allow Non Dir to "True". The protection relay does
not accept the Pickup value or Pickup value Mult setting if the product of
these settings exceeds the Pickup value setting range.
Typically, the ENA_MULT input is connected to the inrush detection function INR. In case
of inrush, INR activates the ENA_MULT input, which multiplies Pickup value by the
Pickup value Mult setting.
Directional calculation
The directional calculation module monitors the angle between the polarizing quantity
and operating quantity. Depending on the Pol quantity setting, the polarizing quantity can
be the residual voltage (measured or calculated) or the negative sequence voltage. When
the angle is in the operation sector, the module sends the enabling signal to the timer
module.
The minimum signal level which allows the directional operation can be set with the Min
trip current and Min trip voltage settings.
If Pol quantity is set to "Zero. seq. volt", the residual current and residual voltage are used
for directional calculation.
If Pol quantity is set to "Neg. seq. volt", the negative sequence current and negative
sequence voltage are used for directional calculation.
1MAC059074-MB A
615 series ANSI
Technical Manual