ABB REL 356

ABB REL 356 Current Differential Protection
5-13
Testing
3. Reverse External Faults
For reverse Zone 2 Phase-Ground External faults use the Table 5-3 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 fron the GANG setting.
Table 5-3. Zone 2 Phase-Ground Reverse External Faults: Z2GF = 4.5 Ohms Z2GR = 0.01 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 2 Phase-Ground Element With Reverse Reach
NOTE: Change the “Z2GR” distance setting to 4.5 ohms before applying the following faults in Tables 5-4, 5-5, and
5-6 to the relay system.
4. Forward Internal Faults
For forward Zone 2 Phase-Ground Internal faults use the following Table 5-4 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% on magnitude and +/- 3 degrees on
phase. Trip time should fall within 100-132 milliseconds.