R
X
Apparent
impedance at
normal load
Z
C
Z
A
Z
B
anglePhi
IEC07000015_2_en.vsd
IEC07000015 V2 EN-US
Figure 238: Impedances to be set for pole slip protection
The setting parameters of the protection is:
Z
A
: Line + source impedance in the forward direction
Z
B
: The source impedance in the reverse direction
Z
C
: The line impedance in the forward direction
AnglePhi
: The impedance phase angle
Use the following data:
UBase
: 400 kV
SBase set to 1000 MVA
Short circuit power at station 1 without infeed from the protected line: 5000 MVA (assumed to a pure
reactance)
Short circuit power at station 2 without infeed from the protected line: 5000 MVA (assumed to a pure
reactance
Line impedance: 2 + j20 ohm
1MRK 504 163-UUS A Section 8
Impedance protection
Transformer protection RET670 2.2 ANSI 473
Application manual
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