ABB REL 356

ABB REL 356 Current Differential Protection
5-16
Testing
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
I
Amps
∠
Angle
Fault Z
Ohms
∠
Angle
Relay System
Operation
AG at MTA -180˚ 50% of reach fault
Va = 30
∠
0 Ia = 8
∠
-255 (105) 2.25
∠
-105
Vb = 69 ∠ -120 (240) Ib = 0
Vc = 69 ∠ -240 (120) Ic = 0
No trips
BG at MTA –180˚ 50% of reach fault
Va = 69 ∠ 0 Ia = 0 2.25 ∠ -105
Vb = 30
∠
-120 (240) Ib = 8
∠
-15 (345)
Vc = 69
∠
-240 (120) Ic = 0
No trips
CG at MTA –180˚ 50% of reach fault
Va = 69 ∠ 0 Ia = 0 2.25 ∠ -105
Vb = 69
∠
-120 (240) Ib = 0
Vc = 30
∠
-240 (120) Ic = 8
∠
-135 (225)
No trips
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
I
Amps
∠
Angle
Fault Z
Ohms
∠
Angle
Relay System
Operation
AG at MTA 90% of reach fault
Va = 25
∠
0 Ia = 2.38
∠
-75 (285) 6.3
∠
75
Vb = 69 ∠ -120 (240) Ib = 0
Vc = 69 ∠ -240 (120) Ic = 0
Z3T Trip
Fault trip AG
Z3G Unit
Trip time 1.0-1.05 S
BG at MTA 90% of reach fault
Va = 69 ∠ 0 Ia = 0 6.3 ∠ 75
Vb = 25
∠
-120 (240) Ib = 2.38
∠
-195 (165)
Vc = 69
∠
-240 (120) Ic = 0
Z3T Trip
Fault trip BG
Z3G Unit
Trip time 1.0-1.05 S
CG at MTA 90% of reach fault
Va = 69 ∠ 0 Ia = 0 6.3 ∠ 75
Vb = 69
∠
-120 (240) Ib = 0
Vc = 25
∠
-240 (120) Ic = 2.38
∠
-315 (45)
Z3T Trip
Fault trip CG
Z3G Unit
Trip time 1.0-1.05 S