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I.L. 40-386.3
∆I
3)
Whe r e n = 1, 2 , 3 , 4 , 5, 6, 7, 8 an d
K = nu m be r of c y cl e s
2.4.11 Ground Directional Polarization Selection
The ground directional unit Dir Type (DIRU) contains three selections Zero Sequence
(ZSEQ), Negative Sequ (NSEQ) and Dual Polariz (DUAL), which determine the operation
of the forward directional overcurrent ground (FDOG) and reversed directional
(RDOG). If the Zero Sequence (ZSEQ) is selected, both FDOG and RDOG units will be
operated by a zero-sequence voltage polarizing element. Forward direction is identified
by the angle, if 3I
3I
> 0.5A and 3V
0
RDOG will be operated by Negative Sequence quantities. The maximum sensitivity for
the forward directional unit is when I
If Dual Polariz (DUAL) is selected, the FDOG and RDOG will be determined by either
zero sequence voltage polarizing element, as the setting of Zero Sequence (ZSEQ) or
current polarizing directional element (I
13 and is from power transformer neutral (ct). The maximum torque angle between 3I
and I
equals zero degrees, i.e., the forward direction is identified when 3I
P
0° to 90° or lags by 0° to 90°. The sensitivity of this element is >3I0.5 and Ip>0.1 Amps.
2.4.12 Instantaneous Forward Directional Overcurrent (FDOG)
The instantaneous forward directional overcurrent ground function (FDOG) is a direc-
tional unit depending on the setting of Dir Type (DIRU) as described in the preceding
section 2.4.11. FDOG is supervised by the Iom setting and controls Zone1, Zone2 and
Zone3 ground units for security purposes.
2.4.13 Instantaneous Reverse Directional Overcurrent Ground (RDOG)
Similar to FDOG, the instantaneous reverse directional overcurrent ground function
(RDOG) supervises the ground units to prevent false trip.
2.4.14 Programmable Reclose Initiation and Reclose Block Logic
The REL 301/302 system provides the following contact output for Reclosing Initiation
and reclosing block functions (Figure 2-19):
• RI2, used for Reclosing Initiation on 3-pole trip
• RB, used for Reclosing Block
The operation of RI2 and RB contacts is controlled by the setting of the programmable
Reclosing Initiation logic (as shown in Figure 2-19). The operation of either RI2, or RB
must be confirmed by the signal of TRSL, which is the trip output of REL 301/302 op-
eration.
The most common Reclosing Initiation practice is to have Reclosing Initiation on high
speed (Pilot, Zone1 and high set overcurrent) trip only. On Pilot version programming
can be accomplished by closing the pilot enable switch and setting the Pilot (PLT) to
YES (Figure 2-19). AND-84 will produce logic to operate the RI2 relay when receiving
signals from TRSL and AND-89.
2-10
i f [ ( 3I
)
- ( 3I
)
0:
0
Kn
0
(K - 1) n
leads 3V
between 30° and 210°. The sensitivity of this element is
0
0,
>1.0 Vac. If Negative Sequ (NSEQ) is selected, both FDOG and
0
] > 0 . 5 amp.
leads V
by 98°, with V
2
2
), which is connected to FT switches #12 and
P
≥ 0.5A.
1.0 Vac and 3I
2
2
leads I
0
P
(10/94)
0
by
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