Setting Guidelines; General; Setting Of Common Parameters - ABB REB670 Applications Manual

Section 11
Secondary system supervision
11.1.3
11.1.3.1
11.1.3.2
274
high value of voltage 3V
condition that is related to a fuse failure event.
The zero sequence detection algorithm, based on the zero sequence measuring quantities
is recommended for use in directly or low impedance grounded networks: a high value of
voltage 3V without the presence of the residual current 3I
0
to a fuse failure event. 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 long 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. Common base IED values for primary
current (IBase), primary voltage (VBase) and primary power (SBase) are set in Global
Base Values GBASVAL. The setting GlobalBaseSel is used to select a particular
GBASVAL and used its base values.

Setting of common parameters

Set the operation mode selector Operation to Enabled to release the fuse failure function.
The voltage threshold VPPU is used to identify low voltage condition in the system. Set
VPPU below the minimum operating voltage that might occur during emergency
conditions. We propose a setting of approximately 70% of VBase.
The drop off time of 200 ms for dead phase detection makes it recommended to always set
SealIn to Enabled since this will secure a fuse failure indication at persistent fuse fail when
closing the local breaker when the line is already energized from the other end. When the
remote breaker closes the voltage will return except in the phase that has a persistent fuse
fail. Since the local breaker is open there is no current and the dead phase indication will
without the presence of the negative-sequence current 3I
2
1MRK 505 337-UUS -
2
is a condition that is related
0
Application manual
is a