2.11 Overcurrent protection
211
7SA522 Manual
C53000-G1176-C155-3
Figure 2-94 Logic diagram of the I
P
–stage (inverse time overcurrent protection), example for IEC characteristics
Stub Protection A further overcurrent stage is the stub protection. It can however also be used as a
normal additional definite time overcurrent stage, as it functions independent of the
other stages.
A stub fault is a short-circuit located between the current transformer set and the line
isolator. It is of particular importance with the 1
1
/
2
circuit breaker arrangements.