ABB REL 356

ABB REL 356 Current Differential Protection
5-19
Testing
11. Forward External Faults
For forward Zone 2 Phase-Phase External faults use the Table 5-11 of voltages and currents. In each case apply the
3-phase voltage to the relay system first then suddenly apply the currents listed. In each case the relay system should
not trip as these faults are beyond the reach of the Zone 2 ground units.
Table 5-11. Zone 2 Phase-Phase Forward External Faults: Z2P = 4.5 Ohms
Volts
∠
Angle
I
Amps
∠
Angle
Fault Z
Ohms
∠
Angle
Relay System
Operation
AB at MTA 110% of reach fault
Va = 17.3
∠
0 Ia = 3.03
∠
-45 (315) 4.95
∠
75
Vb = 17.3 ∠ -120 (240) Ib = 3.03 ∠ -225 (135)
Vc = 69 ∠ -240 (120) Ic = 0
No Trips
BC at MTA 110% of reach fault
Va = 69
∠
0 Ia = 0 4.95
∠
75
Vb = 1.73 ∠ -120 (240) Ib = 3.03 ∠ -165 (195)
Vc = 1.73 ∠ -240 (120) Ic = 3.03 ∠ -345 (15)
No Trips
CA at MTA 110% of reach fault
Va = 17.3
∠
0 Ia = 3.03
∠
-105 (255) 4.95
∠
75
Vb = 69 ∠ -120 (240) Ib = 0
Vc = 17.3 ∠ -240 (120) Ic = 3.03 ∠ -285 (75)
No Trips
12. Reverse External Faults
For reverse Zone 2 Phase-Phase External faults use the Table 5-12 of voltages and currents. In each case apply the 3-
phase voltage to the relay system first then suddenly apply the currents listed. In each case the relay system should
not trip as these faults are reverse direction from the PANG setting.
Table 5-12. Zone 2 Phase-Phase Reverse External Faults: Z2P = 4.5 Ohms
Volts
∠
Angle
I
Amps
∠
Angle
Fault Z
Ohms
∠
Angle
Relay System
Operation
AB at MTA -180˚ 50% of reach fault
Va = 17.3
∠
0 Ia = 6.66
∠
-225 (135) 2.25
∠
-105
Vb = 17.3 ∠ -120 (240) Ib = 6.66 ∠ -45 (315)
Vc = 69 ∠ -240 (120) Ic = 0
No Trips
BC at MTA -180˚ 50% of reach fault
Va = 69
∠
0 Ia = 0 2.25
∠
-105
Vb = 1.73 ∠ -120 (240) Ib = 6.66 ∠ -345 (15)
Vc = 1.73 ∠ -240 (120) Ic = 6.66 ∠ -165 (195)
No Trips
CA at MTA -180˚ 50% of reach fault
Va = 17.3
∠
0 Ia = 6.66
∠
-285 (75) 2.25
∠
-105
Vb = 69 ∠ -120 (240) Ib = 0
Vc = 17.3 ∠ -240 (120) Ic = 6.66 ∠ -105 (255)
No Trips