ABB Relion 670 series - Page 169

Calculation
Idiff and Ibias
Calculation
instantaneous
Idiff
Pickup
and trip
logic
TRIP
Signals
PICKUP
Signals
BLOCK
Signals
Intern/
extern
Fault
Phasors IAN, IBN,ICN
Phasors IAT, IBT,ICT
Samples IAN, IBN,ICN
Samples IAT, IBT,ICT
Magnitude
Idiff and Ibias
Samples Idiff
Diff.prot.
characteristic
Hamonic
analysis: DC,
2nd and 5th
Pickup
phase
selective
Phasor IAN (neg.seq.)
Phasor IAT (neg.seq.)
Internal/
External Fault
Discriminator
and Sensitive
differential
protection
Calculation
negative
sequence
Idiff
Harm.
Block
Analog
Outputs
INTFAULT
EXTFAULT
OPENCT
OPENCTAL
en06000434-2_ansi.vsd
The sensitive protection is deactivated
above bias current > 150 % rated
current.
ANSI06000434 V2 EN-US
Figure 57: Simplified principle design of the Generator differential protection GENPDIF (87G)
Simplified logic diagrams of the function are shown in figures 58, 59, 60 and 61.
1MRK 502 066-UUS B Section 6
Differential protection
163
Technical manual