8.21
Under impedance protection for generators and
transformers ZGVPDIS
GUID-1A3A4890-5CFA-417B-BDA4-EA001502AA60 v2
8.21.1
Identification
GUID-752C21F4-972E-4E97-AB15-075FF720527F v2
Function description
IEC 61850
identification
IEC 60617
identification
ANSI/
IEEEidentification
Under impedance function for
generators and transformers
ZGVPDIS
S00346 V1 EN-US
21G
8.21.2
Application
GUID-ACC76B44-C071-4034-AB9D-880A77E12E66 v2
Under impedance protection for generator is generally used as back up protection for
faults on generator, transformer and transmission lines. Zone 1 can be used to provide
high speed protection for phase faults in the generator, bus ducts or cables and part of
the generator transformer. Zone 2 can be used to cover generator transformer and
power plant's substation bus-bar. Zone 3 can be used to cover power system faults.
The under impedance protection is provided with undervoltage detection feature in
order to provide the seal-in for the impedance based trip. Additionally, it is provided
with load encroachment feature in order to avoid tripping of the protection during
heavy load conditions. The load encroachment functionality is based on the positive
sequence components of voltage and current.
Characteristics of backup impedance protection
Characteristics of zone 1, zone 2 and zone 3 are shown in figure
. All zones have
offset mho characteristics with adjustable reach in forward and reverse direction. The
characteristic angle for all three zones is common and adjustable. A load encroachment
blinder feature is provided for zone 2 and zone 3.
Protection designed to operate for below types of faults
Faults in the generator, generator terminal connections to the step-up transformer and
in the low voltage (LV) side of the generator step-up transformer are:
1MRK 504 163-UUS A
Section 8
Impedance protection
Transformer protection RET670 2.2 ANSI
501
Application manual
Summary of Contents for RELION RET670
Page 1: ...RELION 670 SERIES Transformer protection RET670 Version 2 2 ANSI Application manual ...
Page 2: ......
Page 48: ...42 ...
Page 64: ...58 ...
Page 74: ...68 ...
Page 104: ...98 ...
Page 194: ...188 ...
Page 518: ...512 ...
Page 618: ...612 ...
Page 648: ...642 ...
Page 666: ...660 ...
Page 672: ...666 ...
Page 682: ...676 ...
Page 844: ...838 ...
Page 868: ...862 ...
Page 956: ...950 ...
Page 964: ...958 ...
Page 1004: ...998 ...
Page 1014: ...1008 ...
Page 1015: ...1009 ...