GE L60 Instruction Manual page 224

5.5 GROUPED ELEMENTS
FLEXLOGIC OPERAND
OPEN POLE OP*
FLEXLOGIC OPERAND
GND DIST Z2 PKP A
5
FLEXLOGIC OPERAND
GND DIST Z2 PKP B
FLEXLOGIC OPERAND
GND DIST Z2 PKP C
NOTE: *D60 ONLY
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
5-122
0
20 ms
0
20 ms
0
20 ms
Figure 5–62: GROUND DISTANCE ZONE 2 TO ZONE 3 OP SCHEME
V_0 > 5 Volts
RUN
ZERO SEQ
DIRECTIONAL
FLEXLOGIC OPERAND
OPEN POLE OP
Figure 5–63: GROUND DIRECTIONAL SUPERVISION SCHEME LOGIC
L60 Line Phase Comparison Relay
SETTING
GND DIST Z2 DELAY:
AND
t
PKP
OR
0
SETTING
GND DIST Z2 DELAY:
AND
t
PKP
OR
0
SETTING
GND DIST Z2 DELAY:
AND
t
PKP
OR
0
OR
AND
t
PKP
t
RST
CO-ORDINATING TIME
Pickup 4.5 cycles, Reset 1.0 cycle
5 SETTINGS
FLEXLOGIC OPERAND
GND DIST Z2 OP A
FLEXLOGIC OPERAND
GND DIST Z2 OP B
FLEXLOGIC OPERAND
GND DIST Z2 OP C
FLEXLOGIC OPERAND
OR
GND DIST Z2 OP
837019A7.CDR
FLEXLOGIC OPERAND
GND DIST Z2 DIR
SUPN
837009A6.CDR
GE Multilin