Directional calculation
The directional calculation module monitors the angle between the polarizing
quantity and operating quantity. Depending on the
Pol quantity
setting, the
polarizing quantity can be the residual voltage (measured or calculated) or the
negative sequence voltage. When the angle is in the operation sector, the module
sends the enabling signal to the timer module.
The minimum signal level which allows the directional operation can be set with the
Min operate current
and
Min operate voltage
settings.
If
Pol quantity
is set to "Zero. seq. volt", the residual current and residual voltage are
used for directional calculation.
If
Pol quantity
is set to "Neg. seq. volt", the negative sequence current and negative
sequence voltage are used for directional calculation.
In the phasor diagrams representing the operation of DEFxPDEF, the polarity of
the polarizing quantity (Uo or U2) is reversed, that is, the polarizing quantity in
the phasor diagrams is either -Uo or -U2. Reversing is done by switching the
polarity of the residual current measuring channel (see the connection diagram in
the application manual). Similarly the polarity of the calculated Io and I
2
is also
switched.
For defining the operation sector, there are five modes available through the
Operation mode
setting.
Table 401: Operation modes
Operation mode Description
Phase angle The operating sectors for forward and reverse are defined with
the settings
Min forward angle
,
Max forward angle
,
Min reverse
angle
and
Max reverse angle
.
IoSin
The operating sectors are defined as "forward" when |Io| x sin
(ANGLE) has a positive value and "reverse" when the value is neg-
ative. ANGLE is the angle difference between -Uo and Io.
IoCos As "IoSin" mode. Only cosine is used for calculating the operation
current.
Phase angle 80 The sector maximum values are frozen to 80 degrees respective-
ly. Only
Min forward angle
and
Min reverse angle
are settable.
Phase angle 88 The sector maximum values are frozen to 88 degrees. Otherwise
as "Phase angle 80" mode.
Polarizing quantity selection "Neg. seq. volt." is available only in the
"Phase angle" operation mode.
The directional operation can be selected with the
Directional mode
setting.
The alternatives are "Non-directional", "Forward" and "Reverse" operation. The
operation criterion is selected with the
Operation mode
setting. By setting
Allow
Non Dir
to "True", non-directional operation is allowed when the directional
information is invalid, that is, when the magnitude of the polarizing quantity is less
than the value of the
Min operate voltage
setting.
Typically, the network rotating direction is counter-clockwise and defined as "ABC".
If the network rotating direction is reversed, meaning clockwise, that is, "ACB",
the equation for calculating the negative sequence voltage component need to be
Protection functions
1MRS757644 H
390 620 series
Technical Manual
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