Distance Element Accuracy - GE Multilin 489 Instruction Manual

CHAPTER 7: TESTING
Current/voltage (5 A unit)
Current
Ian = 5 A∠0°
Ibn = 5 A∠120° lag
Icn = 5 A∠240° lag
Ian = 6 A∠0°
Ibn = 6 A∠120° lag
Icn = 6 A∠240° lag
Ian = 10 A∠0°
Ibn = 10 A∠120° lag
Icn = 10 A∠240° lag
Ian = 10 A∠0°
Ibn = 10 A∠120° lag
Icn = 10 A∠240° lag
Ian = 10 A∠0°
Ibn = 10 A∠120° lag
Icn = 10 A∠240° lag
4 activated; 8 Not Activated

7.3.11 Distance Element Accuracy

489 GENERATOR MANAGEMENT RELAY – INSTRUCTION MANUAL
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Voltage
expected
Vab = 120 V∠0° lag
Vbc = 120 V∠120° lag
8
Vca = 120 V∠240° lag
Vab = 120 V∠0°
Vbc = 120 V∠120° lag 4
Vca = 120 V∠240° lag
Vab = 120 V∠0°
Vbc = 120 V∠120° lag
4
Vca = 120 V∠240° lag
Vab = 100 V∠0°
Vbc = 100 V∠120° lag
4
Vca = 100 V∠240° lag
Vab = 60 V∠0°
Vbc = 60 V∠120° lag 4
Vca = 60 V∠240° lag
The theoretical impedance on the R-X plane can be calculated as:
0.875 × Z × cos ( θ θ
–
d d
Z ----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------- -
=
i
where: Z = programmed distance impedance
d
θ = programmed distance characteristic angle
d
θ = variable angle on the R-X plane at point i for which boundary
i
impedance is to be calculated
It is recommended that voltage is kept constant while increasing the current magnitude at
certain angles referenced to voltage phase A until element operates.
Then the expected operating current (assuming that current in the two phases are 180°
apart) can be calculated as:
jθ
i
where Z Z × e .
=
i i
Alarm
observed delay expected
N/A
8
8
4
4
4
) ( 0.875 × Z × cos ( θ θ
+ –
i d d
2
V V
–
a b
I
-----------------
=
i
2Z
i
Trip Trip Delay
observed expected observed
N/A N/A
N/A N/A
11.8 s
6.6 s
1.7 s
2 2
) ) 4 × Z × 0.125
+
i d
(EQ 7.10)
(EQ 7.11)
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