ABB REG670 - Function Block; Functionality; Identification; Under Impedance Protection for Generators and Transformers ZGVPDIS

7.10 Under impedance protection for generators and
transformers ZGVPDIS
7.10.1 Identification
Function description IEC 61850
identification
IEC 60617
identification
ANSI/
IEEEidentification
Under impedance function for
generators and transformers
ZGVPDIS
S00346 V1 EN
21G
7.10.2 Functionality
The under impedance protection is a three zone full scheme impedance protection
using offset mho characteristics for detecting faults in the generator, generator-
transformer and transmission system. The three zones have fully independent
measuring loops and settings. The functionality also comprises an under voltage seal-
in feature to ensure issuing of a trip even if the current transformer goes into saturation
and, in addition, the positive-sequence-based load encroachment feature for the
second and the third impedance zone. Built-in compensation for the step-up
transformer vector group connection is available.
7.10.3 Function block
ZGVPDIS
I3P*
U3P*
BLOCK
BLKZ
BLKUV
TRIP
TRZ1
TRZ2
TRZ3
TRUV
START
STZ1
STZ2
STZ3
STUV
IEC14000018-1-en.vsd
IEC14000018 V1 EN
Figure 145: ZGVPDIS function block
1MRK502052-UEN B Section 7
Impedance protection
319
Technical manual