ABB REL670 2.2 IEC - Load Impedance Limitation, with Load Encroachment Function Activated

All this is applicable for all measuring zones when no power swing detection
element is in the protection scheme. Use an additional safety margin of
approximately 20% in cases when a power swing detection element is in the
protection scheme, refer to the description of Power swing detection (ZMRPSB)
function.
8.1.3.9 Load impedance limitation, with load encroachment function
activated
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The parameters for load encroachment shaping of the characteristic are found in the
description of the phase selection with load encroachment function, section
"Setting guidelines". If the characteristic for the impedance measurement is shaped
with the load encroachment algorithm, the parameter RLdFw and the
corresponding load angle ArgLd must be set according to the minimum load
impedance.
8.1.3.10 Setting of minimum operating currents
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The operation of the distance function can be blocked if the magnitude of the
currents is below the set value of the parameter IMinOpPP and IMinOpPE.
The default setting of IMinOpPP and IMinOpPE is 20% of IBase where IBase is
the chosen base current for the analog input channels. The value has been proven in
practice to be suitable in most of the applications. However, there might be
applications where it is necessary to increase the sensitivity by reducing the
minimum operating current down to 10% of IED base current. This happens
especially in cases, when the IED serves as a remote back-up protection on series
of very long transmission lines.
If the load current compensation is activated, there is an additional criteria
IMinOpIN that will block the phase-earth loop if the 3I0<IMinOpIN. The default
setting of IMinOpIN is 5% of the IED base current IBase.
The minimum operating fault current is automatically reduced to 75% of its set
value, if the distance protection zone has been set for the operation in reverse
direction.
8.1.3.11 Setting of timers for distance protection zones
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The required time delays for different distance-protection zones are independent of
each other. Distance protection zone1 can also have a time delay, if so required for
selectivity reasons. One can set the time delays for all zones (basic and optional) in
a range of 0 to 60 seconds. The tripping function of each particular zone can be
inhibited by setting the corresponding Operation parameter to Off. Different time
delays are possible for the ph-E (tPE) and for the ph-ph (tPP) measuring loops in
each distance protection zone separately, to further increase the total flexibility of a
distance protection.
1MRK 506 369-UEN B Section 8
Impedance protection
Line distance protection REL670 2.2 IEC 201
Application manual