General Protection Data - Siemens siprotec 7SA6 User Manual

Functions
6.1.3

General Protection Data

Rating of the
Protected System
General Line Data
6-16
General protection data (36\VWHP 'DWD ) includes settings associated with all
functions rather than a specific protective or monitoring function. In contrast to the
Power System Data 1 (36\VWHP 'DWD ) as discussed in Sub-section 6.1.1, these
settings can be changed over with the setting groups. To modify these settings, select
the 6(77,1*6 menu option *URXS $ (setting group A), and then 3RZHU 6\VWHP
'DWD  36\VWHP 'DWD  .
The other setting groups are *URXS % *URXS &, and *URXS ', as described in
Subsection 6.1.2.
The rated primary voltage (line voltage) and rated primary current (phase) of the
protected system are entered in the address  )XOO6FDOH9ROW and 
)XOO6FDOH&XUU. These parameters influence the display of the operational
measured values in percent. If these ratings correspond to those of the voltage and
current transformers, the settings are the same as those in address  and 
(Section 6.1.1).
The settings of the line data in this case refers to the common data which is
independent on the actual distance protection grading.
The line angle (Address  /LQH $QJOH) may be derived from the line parameters.
The following applies:
X
L
ϕ
------ -
tan
=
R
L
where R being the resistance and X
L
parameters may either apply to the entire line length, or be per unit of line length as
the quotient is independent of length. Furthermore it makes no difference if the
quotients were calculated with primary or secondary values.
The line angle plays an important role e.g. for the form of the polygons in the distance
protection or in the earth impedance matching with magnitude and angle.
Calculation example:
110 kV overhead line 150 mm
= 0.19 Ω/km
R'
1
= 0.42 Ω/km
X'
1
The line angle is computed as follows
X X'
L 1
tan ϕ
------ - ------- -
= = =
R R'
L 1
In address 1105 the setting /LQH $QJOH = ° is entered.
The per unit length reactance X' is entered as relative quantity [ , in address  in
Ω/km, when for example the unit of length is given in NP (Address , refer to
Section 6.1.1 under "8QLWV RI /HQJWK" or under address  in Ω/mile, when the
unit of length is given in 0LOHV. The corresponding line length is entered in address
 /LQH /HQJWK in kilometres or under address  /LQH /HQJWK in miles. If
the unit of length in address 0236 is changed after the per unit length impedances in
ϕ
or
the reactance of the protected line. The line
L
2
with the following data
0.42 Ω /km
---------------------------- - 2.21
=
0.19 Ω /km
X
 
L
arc tan ------ -
=
 
R
L
ϕ
65.7°
=
C53000-G1176-C133-1
7SA6 Manual