ABB RET670 Applications Manual page 227

1MRK504116-UUS C
Application manual
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IEC06000610 V1 EN
Figure 89: Short circuit currents for the fault at the end of 500 km long 500 kV line
without and with SC
Location of instrument transformers
Location of instrument transformers relative to the line end series capacitors plays an
important role regarding the dependability and security of a complete protection
scheme. It is on the other hand necessary to point out the particular dependence of
those protection schemes, which need for their operation information on voltage in IED
point.
Protection schemes with their operating principle depending on current measurement
only, like line current differential protection are relatively independent on CT location.
Figure 90 shows schematically the possible locations of instrument transformers
related to the position of line-end series capacitor.
- jX
C
CT 1
VT1
ANSI06000611 V1 EN
Figure 90: Possible positions of instrument transformers relative to line end series
capacitor
Bus side instrument transformers
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t[ms ]
CT 2
VT 2
en06000611_ansi.vsd
Section 3
IED application
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