ABB REG650 - Function Block; Functionality

7.2.2 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.
IEC07000117-2-en.vsd
jX
Operation area Operation area
R
Operation area
No operation area No operation area
IEC07000117 V2 EN
Figure 65: Load encroachment influence on the offset mho Z3 characteristic
7.2.3 Function block
IEC10000122-2-en.vsd
ZGCPDIS
I3P*
U3P*
BLOCK
BLKZ
LDCND
TRIP
TRZ1
TRZ2
TRZ3
START
STZ1
STZ2
STZ3
IEC10000122 V2 EN
Figure 66: ZGCPDIS function block
1MRK 502 048-UEN A Section 7
Impedance protection
147
Technical manual