ABB RER620, Technical Manual

Page: 146 / 584

Section 4
1MAC309294-MB F
Protection functions
140 RER620
Technical Manual
For defining the operation sector, there are five modes available through the Operation
mode setting.
Table 162: Operation modes
The directional operation can be selected with the Directional mode setting. The user can
select either “Non-directional”, “Forward” or “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 directional information is invalid.
The Characteristic angle setting is used in “Phase angle” mode to adjust the operation
according to the method of neutral point earthing so that in an isolated network the
Characteristic angle (φ
RCA
) = -90° and in a compensated network φ
RCA
= 0°. In addition,
the characteristic angle can be changed via the control signal
RCA_CTL
, in which case the
alternatives are -90° and 0°. The operation of
RCA_CTL
depends on the Characteristic
angle setting.
The Correction angle setting can be used to improve selectivity when there are
inaccuracies due to measurement transformers. The setting decreases the operation sector.
The correction can only be used with the “IoCos” or “IoSin” modes.
The minimum signal level which allows directional operation can be set by using the Min
trip current and Min trip voltage settings.
When polarizing quantity (residual voltage (-Uo)) is inverted because of switched voltage
measurement cables, the correction can be done by setting the
Pol reversal to “True”
which turns polarizing quantity by 180 degrees.
The directional calculation module calculates several values which are presented in the
monitored data.
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
the mathematical expression has a positive value
and “reverse” when the value is negative
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, respectively. 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.
For definitions of different directional earth-fault characteristics, see the
Directional earth-fault characteristics section in this manual.