GE D90 Plus Instruction Manual page 618
Line distance protection system
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Also See for D90 Plus:
- Instruction manual (694 pages) ,
- Communications manual (222 pages) ,
- Instruction manual (688 pages)
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Plus
THE D90
DISTANCE ELEMENTS
Mho phase AB element analysis
608
When memory expires, the D90
following values are calculated for the mho phase A to ground distance element.
The ground distance element checks for the following conditions for overcurrent
supervision and the difference angles.
Table 18: Mho phase A to ground element conditions
Parameter
Overcurrent supervision
Mho difference angle
Reactance difference angle
Zero-sequence directional
difference angle
Negative-sequence
directional difference angle
Fault type comparator
difference angle
The results are shown in the following table.
Table 19: Mho phase A to ground element analysis
Parameter
Overcurrent supervision
Mho difference angle
Reactance difference angle
Zero-sequence directional
difference angle
Negative-sequence
directional difference angle
Fault type comparator
difference angle
All the comparators and the overcurrent supervision are satisfied. The zone 1 mho phase A
ground distance element will operate for this fault.
The zero-sequence directional difference angle for zones 2 through 4 (phase A) is | 19.8° –
8.4° | = 11.4° < 90°. Therefore, the phase A ground distance elements will pickup, timeout,
and operate.
The following values are calculated for the mho phase AB distance element.
The phase distance element checks for the following conditions for overcurrent
supervision and the difference angles.
Plus
will use the actual voltage for polarization. The
Condition
Supervision
3 × I_0 >
| ∠(I
× Z + I_0 × K
× Z
+ I
× K
A
0
R
G
Comparator Limit
| ∠(I
× Z + I_0 × K
× Z
+ I
× K
A
0
R
G
Comparator Limit
| ∠( I_0 × Z
) – ∠(V
Directional Comparator Limit
_1M) | <
D
A
| ∠( I
) – ∠(V
_2 × Z
_1M) | <
A
D
A
| ∠( I
) – ∠(I_0 × Z
_2 × Z
) | < 50°
A
D
D
Calculation
3 × 13.7 A = 4.09 A
| –3.9° – (–2.1°) | = 1.8°
| –3.9° – 19.8° | = 23.7°
| 19.8° – (–2.1°) | = 21.9°
| 19.8° – (–2.1°) | = 21.9°
| 19.8° – 19.8° | = 0.0°
PLUS
D90
LINE DISTANCE PROTECTION SYSTEM – INSTRUCTION MANUAL
CHAPTER 15: THEORY OF OPERATION
) – ∠(V
× Z – V
_1M) | <
0M
A
A
) – ∠(I_0 × Z) | <
× Z – V
0M
A
Directional Comparator Limit
Requirement
Condition met
> 3 A
Yes
< 75°
Yes
< 75°
Yes
< 75°
Yes
< 75°
Yes
< 50°
Yes
Eq. 57
Eq. 58
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