ABB REO 517 Applications Manual page 74


64
3 zone impedance protection (Z(n)RW)
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The measuring algorithm for one loop and three measuring zones is included in a digital
signal processor. Further signal processors of the same type are added if further mea-
suring loops are to be supervised. Allocation of respective measurement loops take
place through an internal, automatic setting procedure.
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L1-N Zone 1 L2-N Zone 1
L1-N Zone 2 L2-N Zone 2
L1-N Zone 3 L2-N Zone 3
Different internal and external signals will affect the operation of the distance protec-
tion, which is shown in a simplified logic diagram for zone 1 in figure 34.
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L1-L2 Zone 1
L1-L2 Zone 2
L1-L2 Zone 3
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