RFPP 1.6 Zload
£
×
load
1.6 Z
£
×
RFPP
EQUATION579 V2 EN-US
(Equation 112)
Equation
is applicable only when the loop characteristic angle for the phase-to-phase
faults is more than three times as large as the maximum expected load-impedance angle. More
accurate calculations are necessary according to equation
RFPP 1.6 Z
loadmin
cos
J
R1PP
X1PP
---------------
–
sin
J
×
×
×
£
EQUATION580 V1 EN-US
(Equation 113)
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.
7.1.3.9
Load impedance limitation, with load encroachment function activated
SEMOD168247-129 v2
The parameters for load encroachment shaping of the characteristic are found in the
description of the phase selection with load encroachment function, section
. 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.
7.1.3.10
Setting of minimum operating currents
SEMOD168247-132 v2
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.
7.1.3.11
Setting of timers for distance protection zones
SEMOD168247-138 v2
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
1MRK 505 343-UEN B
Section 7
Impedance protection
189
Application manual
Содержание Relion 670 series
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