Page 292 - Practical Power System and Protective Relays Commissioning

286 Practical Power System and Protective Relays Commissioning

t:operation 1
Then TM 5 5 5 0:654
T R 1:528
Relay setting:
I set 5 1440 A
5 1.44 A (secondary)
PSM 5 80 TM 5 0.65
Operation time at a fault after end B will be:

0:14
t 5 0:65 0:0221 5 0:993s
80
For an earth fault relay at end A connected to the residual connection of
CTs at end A:
MVA b 3 100 100 3 100
%Z S 5 5 5 0:144
80 3 O3 3 500
MVA F
For a single phase fault at end B we draw the sequence network diagram
as shown in Fig. 19.2.2.
PSM calculation:
I F 5 29.3 KA I set 5 800 A

FIGURE 19.2.2 Sequence networks.
Z t 5 3Z s 1 2Z 1 1 Z 0
5 3 3 0:144 1 2 3 0:3 1 0:15
5 0:432 1 0:6 1 0:15 5 1:182%

100:100
I 0 5 5 9:769 KA
1:182 3 O3 3 500
I F 5 3I 0 5 3 3 9:769 5 29:3KA
I set 5 800 A
800
I set 5 5 0:8 A secondaryÞ
ð
1000