Protection Engineering Basics and Schemes Protection Engineering | Page 120

3phase short circuit current level , one example of such
settings are given below
Section
Rating
(MVA) Short
circuit
MVA
Power
Grid
Transfor
mer 1-
33KV
Transfor
mer 1-
11KV
Transfor
mer 2-
11KV
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
Another example,
Feede
r
Name Statu
s
State
XXYY Singl
e
Cable
pg. 120
Feede
r Hits
at Feede
r Hits
IN Type
of
Relay CT
Ratio
S/S State
XXYY CDG
31 400/
5
Relay
Protectio
n
A (O/C)
E/F
C (O/C)
Pick- Curren
up
t
curren setting
t A
A
2.5
1
2.5
Plug
setting
multiplay
er (P.S.M)
Time-
setting
multipli
er
0.2
0.1
0.2