Ormazabal ekor.rps - Page 69

IG-150-EN version 04; 03/10/16
69
General instructions
ekor.rps
Protection functions. Description and settings
4.6.10. Neutral directional (67N); watimetric directional
It is used for lines with compensations by means of Petersen
coil.
In order to allow the pick up of the directional unit the
following must be fullled:
1. Exceed the V
n
minimum threshold.
2. For forwards faults the angle between the current and
the voltage, displaced the maximum torque angle, and
must be between 97 and 263.
3. 97<ang(I
0
)– angle(V
0
)+angle characteristics<263.
4. For backwards faults the angle between the current
and the voltage, displaced the maximum torque angle,
and must be between 277 and 83.
5. 277<ang(I
0
)–angle(V
0
)+angle characteristics<83.
6. The power P = V
r
•I
r
•cos (j-j
c
) must exceed the P
minimum threshold in absolute value. If P sign is
negative, the fault is forward. It is positive it is reverse.
The equation to calculate P is the following one:
P =
(
Re(V) ⋅ cos(φ) + Im(V) ⋅ sin(φ)
)
⋅ Re(I) +
(
Im(V) ⋅ cos(φ) – Re(V) ⋅ sin(φ)
)
⋅
Im(I)
1
Tripping Zone
2
Locking zone
Figure 4.10. Neutral directional