Hitachi Relion 670 Series Applications Manual page 144

Section 7
Impedance protection
Trafo 132/15kV
U
V
IEC15000302 V2 EN-US
Trafo 132/66kV
U
V
IEC15000304 V2 EN-US
Figure 50:
ZGTPDIS function can be used as primary protection as well as backup protection for the
transformer. It protects both HV and LV side of the transformer. The protection is designed to operate
for earth faults and phase faults in the transformer and the associated lines.
Zone 1 can be used to provide high-speed protection for faults in the HV winding of the transformer.
Zone 2 can be used to cover the entire transformer and substation LV busbar. Zone 3 can be used to
cover power system faults beyond the LV busbar.
Backup impedance protection characteristics
The characteristics of zone 1, zone 2 and zone 3 are shown in Figure 51. All zones have either offset
mho or non-directional quadrilateral characteristics with adjustable reach in forward and reverse
direction. Quadrilateral characteristics have additional resistive blinders in forward and reverse
direction. The quadrilateral characteristic limits the resistive reach and helps to avoid incorrect
operations due to load encroachment. All three zones have the same characteristic angle which can
be adjusted using ImpCharAng setting.
138
132kV
2-phase to 1-phase interconnection
132kV
2-phase to 2-phase interconnection
Railway transformers connection examples
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1MRK506375-UEN Rev. N
15kV
V
IEC15000302-1-en.vsdx
U
66kV
V
IEC15000304-2-en.vsdx
Railway application RER670
Application manual