2
3
4
6
7
8
9
10
Io / % of I
n
0
90
45
30
15
75
60
-90
-45 -30 -15
-75 -60
Min forward angle
1
80 deg
70 deg
Operating zone
Non-
operating
zone
3% of In
1% of In
Figure 202: Phase angle 80 amplitude ( Directional mode = Forward)
Phase angle 88
The operation criterion phase angle 88 is selected with the
Operation mode setting
using the value "Phase angle 88".
Phase angle 88 implements the same functionality as the phase angle but with the
following differences:
• The
Max forward angle and Max reverse angle settings cannot be set but they
have a fixed value of 88 degrees
• The sector limits of the fixed sectors are rounded.
Sector rounding in the phase angle 88 consists of three parts:
• If the current amplitude is between 1...20 percent of the nominal current, the
sector limit increases linearly from 73 degrees to 85 degrees
• If the current amplitude is between 20...100 percent of the nominal current, the
sector limit increases linearly from 85 degrees to 88 degrees
• If the current amplitude is more than 100 percent of the nominal current, the
sector limit is 88 degrees.
There is no sector rounding on the other side of the sector.
1MRS757644 H
Protection functions
620 series
Technical Manual
407
