Date Code 20011026 Specifications 2-3
SEL-321/321-1 Instruction Manual
Settings Zone 1 Zone 2 Zone 3 Zone 4
Zone Reach Z1P Z2P Z3P Z4P
O/C Supervisory 50PP1 50PP2 50PP3 50PP4
Outputs
Instantaneous M1P M2P M3P M4P
Time Delayed M2PT M3PT M4PT
Supporting Drawings: Figure 2.5 through Figure 2.9
GROUND MHO AND QUADRILATERAL DISTANCE CHARACTERISTICS
Each zone has separate phase and residual overcurrent supervision. The Zone 1 zero-sequence
compensation factor (k01) is independent from the compensation factor (k0) used for all other
zones.
Settings
Zone 1 Zone 2 Zone 3 Zone 4
Mho Reach Z1MG Z2MG Z3MG Z4MG
Quad Reactance XG1 XG2 XG3 XG4
Quad Resistance RG1 RG2 RG3 RG4
Phase O/C Sup. 50L1
1
50L2 50L3 50L4
Res. O/C Sup. 50G1 50G2 50G3 50G4
k0 magnitude k01M k0M k0M k0M
k0 angle k01A k0A k0A k0A
Outputs
Instantaneous Z1G Z2G Z3G Z4G
Time Delayed Z2GT Z3GT Z4GT
1
50L1 is also used for open pole logic and trip unlatch logic.
(The mho and quadrilateral characteristics share the same logical outputs Z1G - Z4G.)
Supporting Drawings: Figure 2.10 through Figure 2.18.
OUT-OF-STEP (OOS) CHARACTERISTICS
The rectangular impedance-plane characteristics use positive-sequence impedance and
overcurrent supervision.
When the impedance remains between Zones 5 and 6 longer than the OOS blocking delay
(OSBD), the relay logic prevents designated zones from tripping for up to two seconds.
Negative-sequence overcurrent conditions, detected by the 50Q1 - 50Q4 elements, remove OOS
blocking to permit tripping for unbalanced faults which may occur during swings.
The OOS characteristics do not affect ground-fault protection.
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