Setting Operating Quantity should be set to "Adaptive" in resonant
earthed systems, except when protected feeders are overcompensated
by distributed coils. In such a case, Operating Quantity should be set
to "Resistive".
Setting Operating Quantity to "Adaptive" enables secure and
dependable directional determination in compensated networks,
which is also valid when the compensation coil is switched off and the
network becomes unearthed. In case of an unearthed network, the
minimum operate current (settings Min Forward Operate Current
and Min Reverse Operate Current) is automatically compared to the
amplitude of
. In case of restriking earth faults, harmonics
created by the fault type make the accumulated sum admittance
phasor behave as in case of an unearthed network. Therefore,
operation can be achieved without the need for resistive part of
. This also means that in compensated networks during earth
faults with rich harmonic content in residual quantities, operation can
be achieved without the parallel resistor of the centralized
compensation coil.
When Operating Quantity is set to "Resistive", settings Min Forward Operate
Current and Min Reverse Operate Current are compared to the resistive component of
in the whole defined operate sector (see Figure 73).
Section 6 1MRS757488 H
Commissioning
126 RIO600
Installation and Commissioning Manual
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