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
I
stab
0
1
. 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
I
stab
0
1
. 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
I
stab
0
1
in the whole defined operate sector (see
Section 6
1MRS757488 H
Commissioning
126
RIO600
Installation and Commissioning Manual
Summary of Contents for Remote I/O RIO600
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