Three-phase electricity in the industrial field can be seen everywhere, and the electrical parameters of three-phase electricity and its power quality problems are also the direction that engineers are tirelessly studying. This article is based on the power analyzer to test the three-phase power related methods, to understand the power test details of three-phase power.
When testing the voltage and current of three-phase electricity, our common wiring methods are divided into 3P3W, 3V3A and 3P4W. The power calculation process for different wiring methods is slightly different.
First, let's take a look at the principle of test power. When calculating the power analyzer sampling, the calculation formula is as follows:
Where u(n) is the voltage signal data (instantaneous data) acquired during the update period, i(n) is the current signal data (instantaneous data) acquired during the update period, and u(n) and i(n) are at the same time. Sample data.
However, we analyze the power calculation process through different wiring methods and the calculation formula mentioned above. The 3P3W wiring method is as follows:
In the above picture, if:
The calculated result is: P=P1+P2.
The wiring of 3V3A is as follows:
For example, the 3P3W inference method, 3V3A wiring test method: P = P1 + P2.
The wiring method of 3P4W is shown in the figure below, and the calculation result is: P=P1+P2+P3.
From the above calculation method, 3P3W and 3V3A two wiring methods, the total power only involves P1, P2, and in the 3V3A wiring mode, the voltage and current test design three measurement channels, and in the final test results, P3 does not play any role. In other words, in the 3V3A wiring mode, there is no way to express the actual meaning of the power of a certain phase. However, in the 3P4W wiring mode, the total power P is composed of the sum of the powers of the three test channels, and the voltage of the three channels is the voltage of the three-phase electric to neutral line, and P1, P2, and P3 can represent each. The power of one phase, that is, in the 3P4W wiring mode, the power of each phase has practical physical meaning.
The application of three-phase power has been deepened in all walks of life, and we must be more cautious in our tests. The common motor uses 3V3A wiring, which can not only observe the balance of its 3-phase power, but also compare its total power. Accurate measurement; in the power industry, we are more common in three-phase four-wire, it is more reasonable to use 3P4W wiring method to test. At present, in addition to power has a professional power quality analyzer, other industries can use power analyzer to measure voltage, current and power.
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