Section 4
1MAC050144-MB C
Protection functions
178
615 series ANSI
Technical Manual
The
RCA_CTL
input is used in compensated networks where the compensation coil
sometimes can be disconnected. When the coil is disconnected, the compensated network
becomes isolated and the
Characteristic angle
setting (
φ
RCA) must be changed. This can
be done automatically with the
RCA_CTL
input. Note that the
RCA_CTL
input only works
when the
Characteristic angle
setting is set to exactly -90 degrees or 0 degrees. The value
of the input affects the
Characteristic angle
setting in the following way:
Table 165: Characteristic angle control in phase angle operation mode
I
0
sin(φ) and I
0
cos(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
) characteristic is used in an isolated
network, measuring the reactive component of the fault current caused by the ground
capacitance. The I
0
cos(
φ
) characteristic is used in a compensated network, measuring the
active component of the fault current.
The operation criteria I
0
sin(
φ
) and I
0
cos(
φ
) are selected with the
Operation mode
setting
using the values "IoSin" or "IoCos", respectively.
In isolated networks, I
0
sin(
φ
) does not differ from the phase angle criterion, since the
phase angle of the operating quantity is fairly close to -90 degrees. Furthermore, in
completely compensated networks the fault current is usually mostly resistive. Therefore,
the phase angle and I
0
cos(
φ
) criteria are equally sensitive. However, if the fault is in the
background network, the fault current of a sound and healthy line is almost fully capacitive
and its phase angle is close to the operation area of the component. Therefore, the I
0
cos(
φ
)
characteristic is recommended, since the risk of faulty operation is smaller than with the
phase angle criterion.
The angle correction setting can be used to improve selectivity. The setting decreases the
operation sector. The correction can only be used with the I
0
sin(
φ
) or I
0
cos(
φ
) criterion.
The
RCA_CTL
input is used to change the I
0
characteristic:
Table 166: Relay characteristic angle control in I
0
sin(φ) and I
0
cos(φ) operation criterion
When the I
0
sin(
φ
) or I
0
cos(
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
Characteristic
angle
setting
RCA_CTL
= "False"
RCA_CTL
= "True"
-90°
φRCA = -90°
φRCA = 0°
0°
φRCA = 0°
φRCA = -90°
Operation criteria:
RCA_CTL
= "False"
RCA_CTL
= "True"
I
0
sin(φ)
Actual operation criterion: I
0
sin(φ)
Actual operation criterion:
I
0
cos(φ)
I
0
cos(φ)
Actual operation criterion:
I
0
cos(φ)
Actual operation criterion: I
0
sin(φ)
Содержание 615 Series ANSI
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Страница 29: ...1MAC050144 MB C Section 615 series ANSI 22 Technical Manual ...
Страница 389: ...Section 4 1MAC050144 MB C Protection functions 382 615 series ANSI Technical Manual ...
Страница 485: ...Section 6 1MAC050144 MB C Supervision functions 478 615 series ANSI Technical Manual ...
Страница 635: ...Section 10 1MAC050144 MB C Other functions 628 615 series ANSI Technical Manual ...
Страница 707: ...Section 15 1MAC050144 MB C Applicable standards and regulations 700 615 series ANSI Technical Manual ...
Страница 711: ...Section 16 1MAC050144 MB C Glossary 704 615 series ANSI Technical Manual ...
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