GE D90 Plus Instruction Manual page 551
Line distance protection system
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Also See for D90 Plus:
- Instruction manual (694 pages) ,
- Communications manual (222 pages) ,
- Instruction manual (662 pages)
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CHAPTER 15: THEORY OF OPERATION
Non-directional mho characteristic
Table 15-1: Non-directional mho characteristic angle calculation parameters
Element
AB phase element
BC phase element
CA phase element
A ground element
B ground element
C ground element
Mho reactance characteristic for directional applications
Table 15-2: Mho reactance characteristic angle calculation parameters
Element
AB phase element
BC phase element
CA phase element
A ground element
B ground element
C ground element
PLUS
D90
LINE DISTANCE PROTECTION SYSTEM – INSTRUCTION MANUAL
Element
A ground element
B ground element
C ground element
The limit angle of the comparator is adjustable. This allows the user to shape the
characteristic as a mho or a lens as shown below. The memory-polarized mho
characteristic has excellent built-in directional integrity. Refer to the Memory polarization
section for additional details.
The non-directional mho characteristic is achieved by checking the angle between the two
values for the various phase and ground distance elements shown in the table below.
Value 1
(I
– I
) × Z – (V
– V
)
A
B
A
B
(I
– I
) × Z – (V
– V
)
B
C
B
C
(I
– I
) × Z – (V
– V
)
C
A
C
A
I
× Z + I_0 × K
× Z + I
× K
A
0
G
0M
I
× Z + I_0 × K
× Z + I
× K
B
0
G
0M
I
× Z + I_0 × K
× Z + I
× K
C
0
G
0M
The mho reactance characteristic is achieved by checking the angle between the two
values for the various phase and ground distance elements shown in the table below.
Value 1
(I
– I
) × Z – (V
– V
A
B
A
(I
– I
) × Z – (V
– V
B
C
B
(I
– I
) × Z – (V
– V
C
A
C
I
× Z + I_0 × K
× Z + I
A
0
I
× Z + I_0 × K
× Z + I
B
0
I
× Z + I_0 × K
× Z + I
C
0
Value 1
I
× Z + I_0 × K
× Z + I
A
0
I
× Z + I_0 × K
× Z + I
B
0
I
× Z + I_0 × K
× Z + I
C
0
Figure 464: Mho and lens characteristics
Value 2
(V
– V
) – (I
A
B
(V
– V
) – (I
B
C
(V
– V
) – (I
C
A
× Z – V
V
– (I
× Z
A
A
A
× Z – V
V
– (I
× Z
B
B
B
× Z – V
V
– (I
× Z
C
C
C
)
B
)
C
)
A
× K
× Z – V
G
0M
A
× K
× Z – V
G
0M
B
× K
× Z – V
G
0M
C
Plus
THE D90
DISTANCE ELEMENTS
Value 2
× K
× Z – V
V
_1M
G
0M
A
A
× K
× Z – V
V
_1M
G
0M
B
B
× K
× Z – V
V
_1M
G
0M
C
C
– I
) × Z
A
B
REV
– I
) × Z
B
C
REV
– I
) × Z
C
A
REV
+ I_0 × K
× Z
+ I
× K
REV
0
REV
G
0M
+ I_0 × K
× Z
+ I
× K
REV
0
REV
G
0M
+ I_0 × K
× Z
+ I
× K
REV
0
REV
G
0M
Value 2
(I
– I
) × Z
A
B
(I
– I
) × Z
B
C
(I
– I
) × Z
C
A
(I_0) × Z
(I_0) × Z
(I_0) × Z
× Z
)
REV
× Z
)
REV
× Z
)
REV
543
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