GE L60 Instruction Manual page 197

5 SETTINGS
FLEXLOGIC OPERAND
OPEN POLE OP
FLEXLOGIC OPERAND
GND DIST Z2 PKP A
FLEXLOGIC OPERAND
GND DIST Z2 PKP B
FLEXLOGIC OPERAND
GND DIST Z2 PKP C
Figure 5–56: GROUND DISTANCE ZONE 2 TO ZONE 3 OP SCHEME
GROUND DIRECTIONAL SUPERVISION:
A dual (zero- and negative-sequence) memory-polarized directional supervision applied to the ground distance protection
elements has been shown to give good directional integrity. However, a reverse double-line-to-ground fault can lead to a
maloperation of the ground element in a sound phase if the zone reach setting is increased to cover high resistance faults.
Ground distance Zones 2 through 3 use an additional ground directional supervision to enhance directional integrity. The
element's directional characteristic angle is used as a 'maximum torque angle' together with a 90° limit angle.
The supervision is biased toward operation in order to avoid compromising the sensitivity of ground distance elements at
low signal levels. Otherwise, the reverse fault condition that generates concern will have high polarizing levels so that a cor-
rect reverse fault decision can be reliably made. The supervision for Zones 2and 3 is removed during open pole conditions.
SETTING
DISTANCE SOURCE:
V_0
I_0
Figure 5–57: GROUND DIRECTIONAL SUPERVISION SCHEME LOGIC
GE Multilin
AND
0
20 ms
OR
AND
0
20 ms
OR
AND
0
20 ms
OR
V_0 > 5 Volts
RUN
OR
ZERO SEQ
DIRECTIONAL
FLEXLOGIC OPERAND
OPEN POLE OP
L60 Line Phase Comparison Relay
5.5 GROUPED ELEMENTS
SETTING
GND DIST Z2 DELAY:
t
PKP
0
SETTING
GND DIST Z2 DELAY:
t
PKP
0
SETTING
GND DIST Z2 DELAY:
t
PKP
0
OR
FLEXLOGIC OPERAND
GND DIST Z2 DIR
AND
SUPN
t
PKP
t
RST
CO-ORDINATING TIME
Pickup 4.5 cycles, Reset 1.0 cycle
FLEXLOGIC OPERAND
GND DIST Z2 OP A
FLEXLOGIC OPERAND
GND DIST Z2 OP B
FLEXLOGIC OPERAND
GND DIST Z2 OP C
FLEXLOGIC OPERAND
GND DIST Z2 OP
837019A6.CDR
837009A6.CDR
5-105
5