However, if the ‘SeriesComp’ option is chosen (only available in ZMFCPDIS) the
value is changed to 0.95.
7.3.7.5 Fuse failure
The ZMFPDIS function has to be blocked by an additional function like the Fuse
failure supervision (FUFSPVC) or an equivalent external device. Typically, the
binary input VTSZ is used for this purpose.
7.3.7.6 Power swings
There is need for external blocking of the ZMFPDIS function during power swings,
either from the Power Swing Blocking function (ZMRPSB) or an external device.
7.3.7.7 Measuring principles
All ZMFPDIS zones operate according to the non-directional impedance
characteristics presented in Figure
82 and Figure 83. The phase-to-earth characteristic
is given in ohms-per-loop domain while the phase-to-phase characteristic is given in
ohms-per-phase domain.
Section 7 1MRK502052-UEN B
Impedance protection
216
Technical manual
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