IG-267-EN versión 01; 07/04/2017
25
General Instructions
ekor
.rpa
Protection functions
The unit will indicate
Forward
direction in the following
conditions:
• The residual current signal (3I
o
) drops in the following
zone:
The residual active power is lower than - P
min
.
The reverse direction zone will be the opposite of the
Forward zone. In other words, the above formula needs to
be turned around 180° in order to achieve the expression
which delimits the reverse direction zone. Furthermore,
residual active power must be greater than + P
min
.
The unit will give undefined direction if:
• The residual active power in absolute value is lower
than P
min
.
• The polarisation voltage value is lower than the V
min
setting.
• This is found in the indeterminate zone (see figure
below).
The figure below shows an example of operation for the
neutral directional unit with wattmetric criterion:
1
Reserve
2
Forward
3
Indeterminate zone
Figure 4.5.
Neutral unit with wattmetric criterion
4.4. Thermal image unit
The
ekor
.rpa-100 model 120 systems are fitted with
the thermal image unit (49) for protection of lines and
transformers.
On certain occasions, the thermal overload of the element
to be protected cannot be detected by conventional
protection units. Furthermore, many of the elements
installed in the power system are being used ever-closer to
their thermal limits, making it necessary for the protection
devices used for these elements to have thermal units.
The thermal image unit is a unit which, in accordance with
the estimated thermal capacity value, generates alarm and
trip signals.
Summary of Contents for ekor.rpa Series
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