R
jX
Operating characteristic
Impedance locus at
power swing
IEC09000224_1_en.vsd
IEC09000224 V1 EN
Figure 225: Impedance plane with Power swing detection operating characteristic
and impedance locus at power swing
8.14.2.2 Basic characteristics
Power swing detection function (ZMRPSB, 78) detects reliably power swings with
periodic time of swinging as low as 200 ms (which means slip frequency as high as 10%
of the rated frequency on the 50 Hz basis). It detects the swings under normal system
operate conditions as well as during dead time of a single-pole automatic reclosing cycle.
ZMRPSB (78) function is able to secure selective operation for internal faults during
power. The operation of the distance protection function remains stable for external faults
during the power swing condition, even with the swing (electrical) centre located on the
protected power line.
The operating characteristic of the ZMRPSB (78) function is easily adjustable to the
selected impedance operating characteristics of the corresponding controlled distance
protection zones as well as to the maximum possible load conditions of the protected
power lines. See the corresponding description in “Technical reference manual” for the
IEDs.
8.14.3 Setting guidelines
Setting guidelines are prepared in the form of a setting example for the protected power
line as part of a two-machine system presented in figure
226.
Section 8 1MRK 506 369-UUS -
Impedance protection
436 Line distance protection REL670 2.2 ANSI
Application manual
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