ROOTECH Accura 2300 Front, Руководство пользователя

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Accura 2300/2350 User Guide Chapter 5 Measurement Description
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2011 Rootech Inc. All Rights Reserved Page 205
Sequence Unbalance
The fundamental signals of 3-phase voltage/current can be decomposed into the symmetrical components
which are positive-sequence, negative-sequence and zero-sequence component.
Fig 5.12 Symmetrical Components
V
b1
V
a1
V
c1
V
b2
V
a2
V
c2
V
a0
V
b0
V
c0
V
a0
=V
b0
=V
c0
positive-sequence negative-sequence zero-sequence
Zero-sequence component(U0): Same component
Positive-sequence component(U1):Symmetrical component for phase sequence A-B-C
Negative-sequence component(U2):Symmetrical component for phase sequence A-C-B
Symmetrical zero-sequence, positive-sequence, and negative-sequence are determined as follows.
[
𝑈
0
𝑈
1
𝑈
2
] =
1
3
∙ [
1 1 1
1 𝑎 𝑎
2
1 𝑎
2
𝑎
] ∙ [
𝑈
𝑎
𝑈
𝑏
𝑈
𝑐
] , 𝑤ℎ𝑒𝑟𝑒 𝑎 = 𝑒
𝑗∙
2𝜋
3
Negative-Sequence Unbalance Ratio
This is the ratio of negative-sequence component based on positive-sequence component.
𝑁𝑒𝑔𝑎𝑡𝑖𝑣𝑒 − 𝑠𝑒𝑞𝑢𝑒𝑛𝑐𝑒 𝑢𝑛𝑏𝑎𝑙𝑎𝑛𝑐𝑒 𝑟𝑎𝑡𝑖𝑜 =
𝑈
2
𝑈
1
× 100 [%]
Zero-Sequence Unbalance Ratio
This is the ratio of zero-sequence component based on positive-sequence component.
𝑍𝑒𝑟𝑜 − 𝑠𝑒𝑞𝑢𝑒𝑛𝑐𝑒 𝑢𝑛𝑏𝑎𝑙𝑎𝑛𝑐𝑒 𝑟𝑎𝑡𝑖𝑜 =
𝑈
0
𝑈
1
× 100 [%]