Chapter 4 Measurements
Accura 3300E User Guide
Page 82
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Symmetrical zero sequence, positive sequence, and negative sequence is 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
Ratio of negative sequence component to positive sequence component.
𝑁𝑒𝑔𝑎𝑡𝑖𝑣𝑒 𝑠𝑒𝑞𝑢𝑒𝑛𝑐𝑒 𝑢𝑛𝑏𝑎𝑙𝑎𝑛𝑐𝑒 𝑟𝑎𝑡𝑖𝑜 =
𝑈
2
𝑈
1
× 100 [%]
Zero Sequence Unbalance Ratio
Ratio of zero sequence component to positive sequence component.
𝑍𝑒𝑟𝑜 𝑠𝑒𝑞𝑢𝑒𝑛𝑐𝑒 𝑢𝑛𝑏𝑎𝑙𝑎𝑛𝑐𝑒 𝑟𝑎𝑡𝑖𝑜 =
𝑈
0
𝑈
1
× 100 [%]
Aggregation
Accura 3300E provides the basic measurement data for the 0.2-second interval by sensing and
processing voltage and current signals every 0.2 seconds. Aggregation for the interval which is
longer than 0.2 seconds is performed, and aggregated values are provided as shown in the
following figure based on the measurement data collected for 0.2 seconds. The figure shows the
aggregation for the intervals of 1 second and 5 seconds. Aggregated values include the average
and maximum/minimum values. The average value is the average of data measured for 0.2
seconds during the aggregation interval. The maximum/minimum values are the
maximum/minimum values among the data collected during 0.2-second intervals within the
aggregation interval.
Fig 4.12 Aggregation Process
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