ABB REG650 Technical Manual page 118

Section 5
Differential protection
Phasors IL1N, IL2N,IL3N
Phasors IL1T, IL2T,IL3T
Samples IL1N, IL2N,IL3N
Samples IAT, IBT,ICT
The sensitive protection is deactivated
above bias current > 150 % rated
Phasor IL1N (neg.seq.)
Phasor IL1T (neg.seq.)
IEC06000434 V3 EN
Figure 53: Principle design of the generator differential protection
112
Magnitude
Idiff and Ibias
Calculation
Idiff and Ibias
Calculation
Samples Idiff
instantaneous
Idiff
current.
Calculation
negative
sequence
Idiff
Simplified logic diagrams of the function is shown in figures below.
Start
phase
selective
Diff.prot.
characteristic
Harm.
Hamonic
Block
analysis: DC,
2nd and 5th
Intern/
Internal/
External Fault extern
Fault
Discriminator
and Sensitive
differential
protection
1MRK 502 034-UEN -
TRIP
Signals
START
Signals
BLOCK
Signals
INTFAULT
Start and
EXTFAULT
trip logic
OPENCT
OPENCTAL
Analog
Outputs
en06000434-2.vsd
Technical Manual