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9/99
Negative Sequence Testing
Follow these steps to test the 46 (Insc>) function:
1. Disable all instantaneous functions - 50P-1 (3I>>1), 50P-2(3I>>2), 50P-3 (3I>>3).
2. Raise the 51P (3I>) Pickup setting to 12A to prevent a 51P (3I>) operation during this test.
3. Set the 46 (Insc>) function according to the following values:
Curve:
•
Pickup:
•
Time Dial:
•
4. Apply the following currents as shown in Figure 11-3:
Ia (L1) = 12 A
•
•
Ib (L2) = 12 A
•
Ic (L3) = 0
This phase-to-phase fault simulation will produce a two per unit negative-sequence current, 6.9A I
= 6.9A), in the DPU1500R.
In = 0
•
5. In this case, I
is determined in the relays as follows:
2
2
I
= 1/3 (Ia + a
2
where:
a = 1
2
a
= 1
since Ic = 0, then
I
= 1/3 (Ia + (1
2
= 1/3 (12
= 1/3 (12
= 1/3 (20.7
∴
I
= 6.9
2
therefore, we are at approximately 2x pickup.
6. The relay should trip between 14.3 and 16.3 seconds (from the Extremely Inverse Curve, Figure 1-6) and only
the NEGATIVE SEQUENCE LED should light.
Maintenance and Testing
Extremely Inverse
3.5A
5.0
0°
)
180°
)
I
+ aIc)
b
120
-120
-
)
120
Ib)
0 + (1
-120) (12
)
0 + 12
60
°)
30
°
30
ABB Distribution Protection Unit 1500R
)
180
website:www.abb.com/papd
, (12A x 58%
2
11-11
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