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9.1 DISTANCE ELEMENTS
Table 9–4: DIRECTIONAL QUADRILATERAL GROUND DISTANCE FUNCTIONS
CHARACTERISTIC
Directional
Directional
Right Blinder
Left Blinder
Fault-type
Zero-sequence
Table 9–5: NON-DIRECTIONAL MHO PHASE DISTANCE FUNCTIONS
CHARACTERISTIC
Offset mho
Table 9–6: NON-DIRECTIONAL MHO GROUND DISTANCE FUNCTIONS
CHARACTERISTIC
Offset mho
Fault-type
Table 9–7: NON-DIRECTIONAL QUADRILATERAL PHASE DISTANCE FUNCTIONS
CHARACTERISTIC
Forward Reactance
Reverse Reactance
Right Blinder
Left Blinder
Table 9–8: NON-DIRECTIONAL QUADRILATERAL GROUND DISTANCE FUNCTIONS
CHARACTERISTIC
Forward Reactance
Reverse Reactance
Right Blinder
Left Blinder
Fault-type
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.
9
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.
9-6
COMPARATOR INPUTS
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
– V
I × Z
REV
REV
I × Z
– V
I × Z
R
R
I × Z
– V
I × Z
L
L
COMPARATOR INPUTS
jΘ
I × Z – V
j × I_0 × e
jΘ
I × Z
– V
–j × I_0 × e
REV
I × Z
– V
I × Z
R
I × Z
– V
I × Z
L
I_0
I_2
D30 Line Distance Protection System
R
L
REV
LIMIT ANGLE
COMP LIMIT
LIMIT ANGLE
COMP LIMIT
COMP LIMIT
jΘ
or j × I_2 × e
jΘ
or –j × I_2 × e
R
L
9.1.4 MEMORY POLARIZATION
9 THEORY OF OPERATION
LIMIT ANGLE
DIR COMP LIMIT
DIR COMP LIMIT
90°
90°
50°
90°
LIMIT ANGLE
COMP LIMIT
50°
90°
90°
LIMIT ANGLE
COMP LIMIT
COMP LIMIT
90°
90°
50°
GE Multilin
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