Setting Guidelines - ABB REL650 Applications Manual

1MRK 506 334-UUS A
10.2.3
10.2.3.1
10.2.3.2
Application manual
solutions are combined to get the best possible effect in the fuse failure supervision
function (SDDRFUF).
SDDRFUF function built into the IED products can operate on the basis of external binary
signals from the miniature circuit breaker or from the line disconnector. The first case
influences the operation of all voltage-dependent functions while the second one does not
affect the impedance measuring functions.
The negative sequence detection algorithm, based on the negative-sequence measuring
quantities, a high value of voltage 3V
current 3I , is recommended for use in isolated or high-impedance grounded networks.
2
The zero sequence detection algorithm, based on the zero sequence measuring quantities,
a high value of voltage 3V
recommended for use in directly or low impedance grounded networks. In cases where the
line can have a weak-infeed of zero sequence current this function shall be avoided.
A criterion based on delta current and delta voltage measurements can be added to the fuse
failure supervision function in order to detect a three phase fuse failure. This is beneficial
for example during three phase transformer switching.

Setting guidelines

General
The negative and zero sequence voltages and currents always exist due to different non-
symmetries in the primary system and differences in the current and voltage instrument
transformers. The minimum value for the operation of the current and voltage measuring
elements must always be set with a safety margin of 10 to 20%, depending on the system
operating conditions.
Pay special attention to the dissymmetry of the measuring quantities when the function is
used on longer untransposed lines, on multicircuit lines and so on.
The settings of negative sequence, zero sequence and delta algorithm are in percent of the
base voltage and base current for the function, VBase and IBase respectively. Set VBase to
the primary rated phase-phase voltage of the potential voltage transformer and IBase to
the primary rated current of the current transformer.
Setting of common parameters
GlobalBaseSel: Selects the global base value group used by the function to define (IBase),
(VBase) and (SBase).
Secondary system supervision
without the presence of the negative-sequence
2
without the presence of the residual current 3I
0
Section 10
, is
0
277