Zone 3 Phase-Ground Element Without Reverse Reach - ABB REL 356 Instruction Booklet

ABB REL 356 Current Differential Protection
6. Reverse External Faults
For reverse Zone 2 Phase-Ground External faults use the Table 5-6 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 GANG setting.
Table 5-6. Zone 2 Phase-Ground Reverse External Faults: Z2GF = 4.5 Ohms Z2GR = 4.5 Ohms
∠
Volts Angle
AG at MTA -180˚ 50% of reach fault
Va = 30 ∠ 0
Vb = 69 ∠ -120 (240)
Vc = 69 ∠ -240 (120)
BG at MTA –180˚ 50% of reach fault
Va = 69 ∠ 0
Vb = 30 ∠ -120 (240)
Vc = 69 ∠ -240 (120)
CG at MTA –180˚ 50% of reach fault
Va = 69 ∠ 0
Vb = 69 ∠ -120 (240)
Vc = 30 ∠ -240 (120)

Zone 3 Phase-Ground Element Without Reverse Reach

NOTE: Change the "T3G" timer setting to 1.0 seconds before applying the faults in Tables 5-7, 5-8, and 5-9.
7. Forward Internal Faults
For forward Zone 3 Phase-Ground Internal faults use the Table 5-7 of voltages and currents. In each case apply the 3-
phase voltage to the relay system first then suddenly apply the currents listed. Compare the relay system trip target
data to the applied fault values. The target data should be within +/- 10% magnitude and +/- 3 degrees on phase. Trip
time should fall within 1.00 - 1.05 seconds.
Table 5-7. Zone 3 Phase-Ground Forward Internal Faults: Z2GF = 7.0 Ohms Z2GR = 0.01 Ohms
∠
Volts Angle
AG at MTA 90% of reach fault
Va = 25 ∠ 0
Vb = 69 ∠ -120 (240)
Vc = 69 ∠ -240 (120)
BG at MTA 90% of reach fault
Va = 69 ∠ 0
Vb = 25 ∠ -120 (240)
Vc = 69 ∠ -240 (120)
CG at MTA 90% of reach fault
Va = 69 ∠ 0
Vb = 69 ∠ -120 (240)
Vc = 25 ∠ -240 (120)
5-16
I
∠
Amps Angle
∠ -255 (105)
Ia = 8
Ib = 0
Ic = 0
Ia = 0
∠ -15 (345)
Ib = 8
Ic = 0
Ia = 0
Ib = 0
∠ -135 (225)
Ic = 8
I
∠
Amps Angle
∠ -75 (285)
Ia = 2.38
Ib = 0
Ic = 0
Ia = 0
∠ -195 (165)
Ib = 2.38
Ic = 0
Ia = 0
Ib = 0
∠ -315 (45)
Ic = 2.38
Fault Z Relay System
∠
Ohms Angle Operation
∠ -105
2.25 No trips
∠ -105
2.25 No trips
∠ -105
2.25 No trips
Fault Z
∠
Ohms Angle
∠ 75
6.3
∠ 75
6.3
∠ 75
6.3
Relay System
Operation
Z3T Trip
Fault trip AG
Z3G Unit
Trip time 1.0-1.05 S
Z3T Trip
Fault trip BG
Z3G Unit
Trip time 1.0-1.05 S
Z3T Trip
Fault trip CG
Z3G Unit
Trip time 1.0-1.05 S
Testing