Simplified, the example can be shown as a triangle, see figure 235.
ZA
ZB
Zload
R
X
en07000016.vsd
IEC07000016 V1 EN-US
Figure 235: Simplified figure to derive StartAngle
0 0
32 52
arctan arctan arctan + arctan = 21.8 + 33.0 55
80 80
³ = »
ZB ZA
angleStart +
Zload Zload
EQUATION1968 V2 EN-US
(Equation 433)
In case of minor damped oscillations at normal operation we do not want the
protection to start. Therefore we set the start angle with large margin.
Set StartAngle to 110°
For the TripAngle it is recommended to set this parameter to 90° to assure limited
stress for the circuit breaker.
In a power system it is desirable to split the system into predefined parts in case of
pole slip. The protection is therefore situated at lines where this predefined split
shall take place.
Normally the N1Limit is set to 1 so that the line will be tripped at the first pole slip.
If the line shall be tripped at all pole slip situations also the parameter N2Limit is
set to 1. In other cases a larger number is recommended.
1MRK 506 369-UEN B Section 8
Impedance protection
Line distance protection REL670 2.2 IEC 431
Application manual
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