ERL L-PRO 4000, Руководство пользователя

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7 Acceptance/Protection Function Test Guide
7-40 L-PRO 4000 User Manual D02706R02.30
46-50/46-51
Negative
Sequence
Overcurrent
Test
Settings
• Directional
• 46-51 Pickup = 1.0 A
• Time Curve = IEEE Extremely Inverse
A = 5.64
B = 0.02434
p = 2
TMS = 3.0
Figure 7.28: Negative Sequence Instantaneous and Time OverCurrent Logic (46-50/
46-51)
Note that positive sequence current (50ILpos), 4% of nominal current is nec-
essary to enable the directional element. This supervision can be seen on OR
265, for details see Figure 7.27: Directional Element Logic on page 7-38.
For this test inject only single-phase current. This method introduces an equal
proportion of positive and negative sequence current. This assures that there is
sufficient positive sequence current to enable directional control of the nega-
tive sequence element, if a polarizing voltage is also applied.
Positive sequence (I1), Negative Sequence (I2), Zero Sequence (3I0) are cal-
culated by using the following equations:
where a = 1

120

(35)
where a = 1

120

(36)
0
50 I2
288
51 I1
If Directional or combined, T must be greater than 10 ms
5ms
T
0
289
46-50 Directional Control
46-51 Directional Control
Timer is active, only if it's directional or combined
Out 8
Alarm
Out 9
I
1
I
A
aI
B
a
2
I
C
+ +
3
--------------------------------------- =
I
2
I
A
a
2
I
B
aI
C
+ +
3
---------------------------------------- =