If the
Allow Non Dir
setting is "False", the directional operation (forward, reverse) is not
allowed when the measured polarizing or operating quantities are invalid, that is, their
magnitude is below the set minimum values. The minimum values can be defined with the
settings
Min trip current
and
Min trip voltage
. In case of low magnitudes, the
FAULT_DIR
and
DIRECTION
outputs are set to 0 = unknown, except when the
Allow
non dir
setting is "True". In that case, the function is allowed to operate in the directional
mode as non-directional, since the directional information is invalid.
Iosin(φ) and Iocos(φ) criteria
A more modern approach to directional protection is the active or reactive current
measurement. The operating characteristic of the directional operation depends on the
grounding principle of the network. The I
0
sin(φ) characteristics is used in an isolated
network, measuring the reactive component of the fault current caused by the ground
capacitance. The I
0
cos(φ) characteristics is used in a compensated network, measuring the
active component of the fault current.
The operation criteria Iosin(φ) and Iocos(φ) are selected with the
Operation mode
setting
using the values "IoSin" or "IoCos" respectively.
The angle correction setting can be used to improve selectivity. The setting decreases the
operation sector. The correction can only be used with the Iosin(φ) or Iocos(φ) criterion.
The
RCA_CTL
input is used to change the IG characteristic:
Table 352:
Relay characteristic angle control in the IoSin and IoCos operation criteria
Operation mode:
RCA_CTL
= "False"
RCA_CTL
= "True"
IoSin
Actual operation criterion: Iosin(φ) Actual operation criterion:
Iocos(φ)
IoCos
Actual operation criterion:
Iocos(φ)
Actual operation criterion: Iosin(φ)
When the Iosin(φ) or Iocos(φ) criterion is used, the component indicates a forward- or
reverse-type fault through the
FAULT_DIR
and
DIRECTION
outputs, in which 1 equals
a forward fault and 2 equals a reverse fault. Directional operation is not allowed (the
Allow
non dir
setting is "False") when the measured polarizing or operating quantities are not
valid, that is, when their magnitude is below the set minimum values. The minimum
values can be defined with the
Min trip current
and
Min trip voltage
settings. In case of
low magnitude, the
FAULT_DIR
and
DIRECTION
outputs are set to 0 = unknown,
except when the
Allow non dir
setting is "True". In that case, the function is allowed to
operate in the directional mode as non-directional, since the directional information is
invalid.
Section 4
1MAC059074-MB A
Protection functions
342
615 series ANSI
Technical Manual
Summary of Contents for Relion 615 series
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