Functionality; Function Block - ABB REG650 Technical Manual

1MRK 502 048-UEN A
7.2.2
7.2.3
Technical manual

Functionality

The underimpedance protection for generators and transformers ZGCPDIS, has the
offset mho characteristic as a three zone back-up protection for detection of phase-to-
phase short circuits in transformers and generators. The full scheme three zones have
independent measuring phase-to-phase loops and settings that gives high flexibility
for all types of applications.
All three zones can be individually definite time delayed.
A load encroachment characteristic is available for the third zone as shown in figure
65.
jX
Operation area Operation area
Operation area
No operation area No operation area
IEC07000117-2-en.vsd
IEC07000117 V2 EN
Figure 65: Load encroachment influence on the offset mho Z3 characteristic

Function block

ZGCPDIS
I3P* TRIP
U3P* TRZ1
BLOCK TRZ2
BLKZ TRZ3
LDCND START
STZ1
STZ2
STZ3
IEC10000122-2-en.vsd
IEC10000122 V2 EN
Figure 66: ZGCPDIS function block
Impedance protection
R
Section 7
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