Protection Engineering Basics and Schemes Protection Engineering | Page 152

 Now, let suppose it is same relay installed at 11KV
side of Transformer 1, which we need to test , as you
can see the pickup setting of Transformer 1-11kv
Overcurrent relay is 1.1818A, so we need to inject
current up to 1.1818A or up to level where relay pick
up.
Section
Power
Grid
Transfor
mer 1-
33KV
Transfor
mer 1-
11KV
Transfor
mer 2-
11KV
pg. 152
Rating
(MVA) Short
circuit
MVA Voltage
level
(KV) Full load
current(Ir
) Short
Circuit
Current
20 117.647
0588 33 349.9195
185 2058.350
109
10 142.857
1429 33 174.9597
593 2499.425
132
10 142.857
1429 11 524.8792
778 7498.275
397
1 17.3913
0435 11 52.48792
778 912.8335
265
Pick
up
1.15
044
2
1.18
181
8
1.18
181
8
1.18
181
8
Instant
aneou
s
Setting
(8*Pic
k up)
9.2035
39823
9.4545
45455
9.4545
45455
9.4545
45455
Earth
Fault
Pick
up
1.017
69911
5
1.045
45454
5
1.045
45454
5
1.045
45454
5
Instant
aneou
s Earth
Fault
Pick up
8.1415
9292
8.3636
36364
8.3636
36364
8.3636
36364