ABB REL 356 Current Differential Protection
5-18
Testing
Phase to Phase Units
To calculate the fault impedance seen by the relay system the following formula applies:
where x is either phase a, b, or c and y is the next lagging phase.
The above formula is rigorous and general. However, if a quick approximation of the minimum trip current required at
different angles (
q
) is desired, the following formula applies:
where x is either phase a, b, or c and y is the next lagging phase.
Zone 2 Phase-Phase Element
10.
Forward Internal Faults
For forward Zone 2 Phase-Phase Internal faults use the Table 5-10 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 /- 10% on magnitude and +/- 3 degrees on phase. Trip
time should fall within 100-132 milliseconds.
Table 5-10. Zone 2 Phase-Phase Forward Internal Faults: Z2P = 4.5 Ohms
Volts
∠
Angle
I
Amps
∠
Angle
Fault Z
Ohms
∠
Angle
Relay System
Operation
AB at MTA 90% of reach fault
Va = 17.3
∠
0
Ia = 3.7
∠
-75 (285)
4.05
∠
75
Vb = 17.3
∠
-120 (240)
Ib = 3.7
∠
-225 (135)
Vc = 69
∠
-240 (120)
Ic = 0
Z2T Trip
Fault trip AB
Z2G Unit
Trip time 100-132 mS
BC at MTA 90% of reach fault
Va = 69
∠
0
Ia = 0
4.05
∠
75
Vb = 1.73
∠
-120 (240)
Ib = 3.7
∠
-165 (195)
Vc = 1.73
∠
-240 (120)
Ic = 3.7
∠
-345 (15)
Z2T Trip
Fault trip BC
Z2G Unit
Trip time 100-132 mS
CA at MTA 90% of reach fault
Va = 17.3
∠
0
Ia = 3.7
∠
-105 (255)
4.05
∠
75
Vb = 69
∠
-120 (240)
Ib = 0
Vc = 17.3
∠
-240 (120)
Ic = 3.7
∠
-285 (75)
Z2T Trip
Fault trip CA
Z2G Unit
Trip time 100-132 mS
Z fault =
Vxy
Ix
Iy
-
--------------
V
XG
Z2P (cos (PANG -
q))
----------------------------------------------------------
lxg =
Summary of Contents for REL 356
Page 23: ...ABB REL 356 Current Differential Protection 1 10 Product Overview and Specifications ...
Page 83: ...ABB REL 356 Current Differential Protection 3 36 Settings and Application ...
Page 127: ...ABB REL 356 Current Differential Protection 5 28 Testing ...
Page 186: ...LINE SECTIONALIZING USING A PLC AND ABB PROTECTIVE RELAY Page 49 of 53 ...
Page 187: ...LINE SECTIONALIZING USING A PLC AND ABB PROTECTIVE RELAY Page 50 of 53 ...
Page 188: ...LINE SECTIONALIZING USING A PLC AND ABB PROTECTIVE RELAY Page 51 of 53 ...
Page 189: ...LINE SECTIONALIZING USING A PLC AND ABB PROTECTIVE RELAY Page 52 of 53 ...