Siemens siprotec 7SD5 User Manual page 59

Calculation Example:
110 kV overhead line 150 mm
The line angle is computed as follows
In address 1105 the setting Line Angle = 66° is entered.
Address 1540 Distance Angle specifies the angle of inclination of the R sections
of the distance protection polygons. Usually you can also set the line angle here as in
address 1105.
The directional values (power, power factor, work and related min., max., mean and
setpoint values), calculated in the operational measured values, are usually defined
with positive direction towards the protected object. This requires that the connection
polarity for the entire device was configured accordingly in the Power System Data 1
(compare also „Polarity of Current Transformers", address 201). But it is also possible
to define by setting the „forward" direction for the protection functions and the positive
direction for the power etc. differently, e.g. so that the active power flow (from the line
to the busbar is indicated in the positive sense. Set under address 1107 P,Q sign
the option reversed. If the setting is not reversed (default), the positive direction
for the power etc. corresponds to the „forward" direction for the protection functions.
The reactance value X' of the protected line is entered as reference value x' in
address 1111 in Ω/km if the distance unit was set as kilometer (address 236, see
Section 2.1.2.1 at „Distance Unit"), or in Ω/mile if mile was selected as distance unit.
The corresponding line length is entered in address 1113 Line Length in kilometers
or in miles. If, after entry of the reactance per unit of line length in address 1111 or of
the line length in address 1113, the distance unit is changed in address 236, the line
data must be entered again for the revised distance unit.
The capacitance per unit length C' of the protected line is required for load current
compensation, for double-ended fault location and for compounding in overvoltage
protection. Without compounding it is of no consequence. It is entered as a reference
value c' at address 1112 in µF/km if kilometers was set as the distance unit (address
236, see Section 2.1.2.1 at „Distance Unit"), or in µF/mile if mile was set as distance
unit. If, after entry of the capacitance per unit of line length in address 1112 or of the
line length in address 1113, the distance unit is changed in address 236, the line data
must be entered again for the revised distance unit.
For calculation of the capacitance of a line system, the entire line length, i.e. the sum
of all line sections, must be set in address 1114 Tot.Line Length. For lines with
more than two ends, this information is required for charging current compensation.
When entering the parameters with a personal computer and DIGSI
optionally also be entered as primary values. If the nominal quantities of the primary
transformers (U, I) are set to minimum, primary values allow only a rough setting of
the value parameters. In such cases it is preferable to set the parameters in secondary
quantities.
7SD5 Manual
C53000-G1176-C169-1
= 0.19 Ω/km
R'
1
= 0.42 Ω/km
X'
1
2
with the following data:
2.1 General
®
the values may
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