Siemens siprotec 7SA522 User Manual

2 Functions
50
7SA522 Manual
C53000-G1176-C155-3
Where
R
0
= Zero sequence resistance of the line
X
0
= Zero sequence reactance of the line
R
1
= Positive sequence resistance of the line
X
1
= Positive sequence reactance of the line
These values may either apply to the entire line length or be based on a per unit of line
length, as the quotients are independent of length. Furthermore it makes no difference
if the quotients are calculated with primary or secondary values.
Calculation Example:
110 kV overhead line 150 mm
2
with the following data:
R
1
/s = 0.19 Ω/km positive sequence impedance
X
1
/s = 0.42 Ω/km positive sequence impedance
R
0
/s = 0.53 Ω/km zero sequence impedance
X
0
/s = 1.19 Ω/km zero sequence impedance
(where s = line length)
For ground impedance ratios, the following emerge:
The earth impedance (residual) compensation factor setting for the first zone Z1 may
be different from that of the remaining zones of the distance protection. This allows the
setting of the exact values for the protected line, while at the same time the setting for
the back-up zones may be a close approximation even when the following lines have
substantially different earth impedance ratios (e.g. cable after an overhead line). Ac-
cordingly, the settings for the address  5(5/=and  ;(;/= are
determined with the data of the protected line while the addresses 
5(5/=%= and  ;(;/=%= apply to the remaining zones
Z1B and Z2 up to Z5 (as seen from the relay location).
Earth Impedance
(Residual) Com-
pensation with
Magnitude and
Angle (K
0
–Factor)
When the complex earth impedance (residual) compensation factor K
0
is set, the ad-
dresses  to  apply. In this case it is important that the line angle is set cor-
rectly (see Address , see paragraph “General Line Data”) as the device needs
the line angle to calculate the compensation components from the K
0
. These earth im-
pedance compensation factors are defined with their magnitude and angle which may
be calculated with the line data using the following equation:

Siemens siprotec 7SA522 Specifications

General

Brand	Siemens
Model	siprotec 7SA522
Category	Protection Device
Language	English