Calculating Settings For Step 2 - ABB REQ650 Applications Manual

1MRK 505 291-UEN A
3.1.5.3
Application manual
Z : Low
SC
3
Three-phase short circuit
IEC10000148 V1 EN
Figure 14: Fault for step 1 setting
Recommended current setting is therefore 2000 A.
1. Set DirMode1 to Forward.
2. Set Characterist1 to IEC Def. Time.
For the time delay characteristic, definite time is used in this network.
3. Set I1> to 200% of IBase (2000 A primary current).
4. Set t1 to 0.4 s.

Calculating settings for step 2

The protection shall be able to detect all short circuits in the own busbar. A two-phase
short circuit in the busbar and high source impedance from the remote line end, as
shown in figure 15, results in the following fault current for the protection:
U
3
ph
= × =
I
sc
+
2 Z Z
sc line
EQUATION2343 V1 EN
REQ650 setting examples
REQ650 (A01)
1
3
Line protection zone 1 reach
145
3
3
× =
2.6 85
+ +
2 j 10 2.5 j 17.5
Section 3
IEC10000148-1-en.vsd
Ð °
kA
49