Normal Power Flow
When set to the X->Y mode, kW and metering values will show as positive for normal
power ow when power is owing into the Y terminal and show as negative for reverse
power ow when power is owing into the X terminal. Selecting the Y->X mode reverses
the application of the sign, resulting in positive for power owing into the X terminal and
negative for power owing into the Y terminal.
Calculations with the default X->Y setting:
• Tota l kVA value as reported on DNP is computed and is the sum of the kVA value from
each pole. The kVA value for each pole is computed as the square root of (kW*kW +
kvar*kvar). So, the Tot al kVA value is always a positive number.
• Total kW value is computed and is the algebraic sum of the kW value from each pole.
This can be negative or positive.
• Total kvar value is computed and is the algebraic sum of kvar value from each pole.
This can be negative or positive.
• For voltage and current owing in the same direction (X->Y), the kW value is positive.
The kvar value is dependent on leading or lagging current.
• For current owing in the opposite direction of voltage (Y->X), the kW value is
negative. The kvar value is dependent on leading or lagging current.
• The MWH value is accumulated separately for the positive kW and negative kW
values. With the X->Y setting, positive power consumption is accumulated into the X->Y
column data, and negative power consumption is accumulated into the Y->X column
data.
System Type
Select from the drop-down list: Multi-Grounded (defau lt), Uni-Grounded, Uni-
Grounded Solid, Uni-Grounded Resistive, Uni-Grounded Reactive, or Uni-
Grounded Resonant. The selection affects how the Overcurrent element and SEF
element directionality are determined.
Directional Protection
Directional fault determination is made based on the signals available within the specied
protection element response times. This means directional determination never retards
IntelliRupter fault interrupter tripping times. However, directional measurements of fully
asymmetric faults improve with longer signal processing times. Consequently, minimum
response times of 2 cycles or greater result in very secure directional determination.
The directional characteristic maximum torque angles used by the IntelliRupter
fault interrupter are only specified for Terminal-Y faults and are shown in Table 1 on
page 23. Therefore, Terminal-X fault maximum torque angles are 180° from those shown
for Terminal-Y. Refer to the Setup>General>System>System Type screen for all system
grounding options.
Table 1 lists the operating current and reference voltages used for torque angle mea-
surements, along with the maximum torque angles (MTA) for Terminal-Y. Torque angles
are combined to determine direction of phase-to-ground, phase-to-phase, phase-to-phase-
to-ground, and three-phase faults. SEF fault direction is determined separately and uses
zero-sequence torque after it has been filtered. SEF filtered zero-sequence torque is used
when the SEF element is the only protection element timing.
22 S&C Instruction Sheet 766-530
General Setup
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