Memory Polarization - GE D60 Instruction Manual

8.1 DISTANCE ELEMENTS
Table 8–4: DIRECTIONAL QUADRILATERAL GROUND DISTANCE FUNCTIONS
CHARACTERISTIC
Reactance
Directional
Directional
Right Blinder
Left Blinder
Fault-type
Zero-sequence
Table 8–5: NON-DIRECTIONAL MHO PHASE DISTANCE FUNCTIONS
CHARACTERISTIC
Offset mho
Table 8–6: NON-DIRECTIONAL MHO GROUND DISTANCE FUNCTIONS
CHARACTERISTIC
Offset mho
Fault-type
Table 8–7: NON-DIRECTIONAL QUADRILATERAL PHASE DISTANCE FUNCTIONS
CHARACTERISTIC
Forward Reactance
Reverse Reactance
Right Blinder
Left Blinder
Table 8–8: NON-DIRECTIONAL QUADRILATERAL GROUND DISTANCE FUNCTIONS
CHARACTERISTIC
Forward Reactance
Reverse Reactance
Right Blinder
Left Blinder
Fault-type
8
All distance functions use memory polarization. The positive-sequence voltage – either memorized or actual – is used as a
polarizing signal. The memory is established when the positive-sequence voltage remains above 80% of its nominal value
for five power system cycles. The memory voltage is a two-cycle old voltage.
Once established, the memory is applied for the user-specified time interval. The memory timer is started when the voltage
drops below 80% of nominal or when the user-programmable condition is asserted to force memory polarization. After the
memory expires, the relay checks the magnitude of the actual positive-sequence voltage. If it is higher than 10% of nomi-
nal, the actual voltage is used; if lower, the memory voltage continues to be used.
A provision is added to force self-polarization from any user-programmable condition.
The memory-polarized mho has an extra directional integrity built-in as illustrated below. The self-polarized mho character-
istic is shifted in the reverse direction for a forward fault by an amount proportional to the source impedance, and in the for-
ward direction for a reverse fault.
8-6
COMPARATOR INPUTS
j
I  Z – V j  I_0  e or j  I_2  e
I_0  Z
V_1M
D
I_2  Z
V_1M
D
I  Z I  Z
– V
R
I  Z I  Z
– V
L
I_0 I_2
I_0  Z
–V_0
D
COMPARATOR INPUTS
I  Z – V V-I  Z
COMPARATOR INPUTS
I  Z – V V-I  Z
REV
I_0 I_2
COMPARATOR INPUTS
I  Z – V I  Z
I  Z I  Z
– V
REV REV
I  Z I  Z
– V
R R
I  Z I  Z
– V
L L
COMPARATOR INPUTS
j
I  Z – V j  I_0  e
j
I  Z –j  I_0  e
– V
REV
I  Z I  Z
– V
R
I  Z I  Z
– V
L
I_0 I_2
D60 Line Distance Protection System
j
DIR COMP LIMIT (removed when 3I_0 > OC SUPV
and I_2 < CUTOFF)
R
L
50° (removed during open pole conditions or when
3I_0 > OC SUPV and I_2 < CUTOFF)
90° (zones and higher only; removed for zones 2 and
higher during open pole conditions)
REV
LIMIT ANGLE
COMP LIMIT
50° (removed during open pole conditions or when 3I_0 > OC
SUPV and I_2 < CUTOFF)
LIMIT ANGLE
COMP LIMIT
COMP LIMIT
j
or j  I_2  e
j
or –j  I_2  e
R
L
50° (removed during open pole conditions or
when 3I_0 > OC SUPV and I_2 < CUTOFF)

8.1.4 MEMORY POLARIZATION

8 THEORY OF OPERATION
LIMIT ANGLE
COMP LIMIT
DIR COMP LIMIT
90°
90°
LIMIT ANGLE
COMP LIMIT
90°
90°
LIMIT ANGLE
COMP LIMIT
COMP LIMIT
90°
90°
GE Multilin