GE L90 Instruction Manual page 703

CHAPTER 10: THEORY OF OPERATION
Phase distance fault type supervision can be enabled/disabled through S
GROUP 1(6)  DISTANCE  PH DIST PH SELECT SUPV
relays do not employ fault type supervision for the phase distance in all zones.
10.3.3.11 Zero-sequence directional characteristic
The extra zero-sequence characteristic applies to ground zones 2 and higher and is achieved by checking angles between:
• A ground element — I_0 × Z
• B ground element — I_0 × Z
• C ground element — I_0 × Z
The limit angle of the comparator is not adjustable and equals 90°. The zero-sequence directional characteristic improves
directional integrity for time-delayed operations after the memory expires.
10.3.3.12 Overcurrent supervision
The overcurrent supervision responds to the following currents:
• AB phase element — (I
A
• BC phase element — (I
B
• CA phase element — (I
C
• A, B, C ground element — | 3 × I_0 – 0.05 × I_1 |
The following tables summarize the characteristics of the distance elements.
Table 10-1: Directional mho phase distance functions
Characteristic Comparator inputs
I × Z – V
Variable mho
I × Z – V
Reactance
I × ZD
Directional
Fault type NOT SLG
Table 10-2: Directional mho ground distance functions
Characteristic Comparator inputs
I × Z – V
Variable mho
I × Z – V
Reactance
I_0 × Z
Directional
D
I_2 × Z
Directional
D
Fault-type I_0
Zero-sequence I_0 × Z
D
Table 10-3: Directional quadrilateral phase distance functions
Characteristic Comparator inputs
Reactance I × Z – V
Directional I × Z
D
Right Blinder I × Z – V
R
Left Blinder I × Z – V
L
Fault type NOT SLG
L90 LINE CURRENT DIFFERENTIAL SYSTEM – INSTRUCTION MANUAL
and is applied to phase distance zone 1 to zone 3 only. G60 and L60
and –V_0
D
and –V_0
D
and –V_0
D
– I ) /
B
– I ) /
C
– I ) /
A
V_1M
I × Z
V_1M
See the Fault Type Characteristic section
V_1M
I_0 × Z
V_1M
V_1M
I_2
–V_0
I × Z
V_1M
I × Z
R
I × Z
L
See the Fault Type Characteristic section
ETTINGS  GROUPED ELEMENTS  SETTING
Limit angle
COMP LIMIT
COMP LIMIT
DIR COMP LIMIT
Removed during open pole conditions
Limit angle
COMP LIMIT
COMP LIMIT
DIR COMP LIMIT
DIR COMP LIMIT (removed when 3I_0 > OC SUPV and I_2 < CUTOFF)
50° (removed during open pole conditions or when 3I_0 > OC SUPV
and I_2 < CUTOFF)
90° (zones 2 and higher only; removed for zones 2 and higher
during open pole conditions)
Limit angle
COMP LIMIT
DIR COMP LIMIT
90°
90°
Removed during open pole conditions
DISTANCE ELEMENTS
10
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