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Equal-period fitting measurement method of power factor in short-circuit test of low-voltage apparatus

A low-voltage electrical appliance and power factor technology, applied in the field of measurement, can solve problems such as difficulty in accurate measurement, achieve high measurement accuracy, avoid current measurement accuracy and frequency instability, and simple measurement methods.

Active Publication Date: 2020-07-10
SHANDONG INST FOR PROD QUALITY INSPECTION
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Problems solved by technology

Under normal circumstances, the allowable deviation of the power supply frequency f of the power system is ±0.2Hz, and in some cases it will reach ±0.5Hz, which will definitely give the power factor the impact coefficient method, the phase cross method and the DC component method. Accurate measurement brings great difficulties

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  • Equal-period fitting measurement method of power factor in short-circuit test of low-voltage apparatus
  • Equal-period fitting measurement method of power factor in short-circuit test of low-voltage apparatus
  • Equal-period fitting measurement method of power factor in short-circuit test of low-voltage apparatus

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Embodiment Construction

[0031] The technical solutions of the present invention will be clearly and completely described below in conjunction with the accompanying drawings. Apparently, the described embodiments are some of the embodiments of the present invention, but not all of them. Based on the embodiments of the present invention, all other embodiments obtained by persons of ordinary skill in the art without making creative efforts belong to the protection scope of the present invention.

[0032] In the description of the present invention, it should be noted that the terms "center", "upper", "lower", "left", "right", "vertical", "horizontal", "inner", "outer" etc. The indicated orientation or positional relationship is based on the orientation or positional relationship shown in the drawings, and is only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the referred device or element must have a specific orientation, ...

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Abstract

The invention discloses an equivalent period fitting measurement method for a low-voltage electric appliance product short circuit tolerance intensity test power factor. According to a principle thati(t) consists of a periodic component Imsin([omega]t+[phi]u-[phi]) and an exponential decay component Imsin([phi]u-[phi]).e<-R / L.t>, the periodic component is a constant value on equal period intervalmoment on an i(t) curve, the Imsin( [phi]u-[phi]) is a constant value after a test loop is closed and therefore the i(t) can be equivalent to i(t)=A+B.e<-t / T> (wherein A, B and T are all constants),multiple groups of equal period current values i(t) are subjected to the curve fitting of a specific exponential decay function i(t)=A+B.e<-t / T>, and a great quantity of power factor measurement calculation values are obtained; then, a linear fitting method is used, a power factor numerical value with highest occurrence frequency is selected from the power factor calculation values to serve as a final test loop power factor; and therefore, an influence brought by unstable current measurement accuracy and frequency is avoided. The measurement method is simple, and measurement accuracy is high.

Description

technical field [0001] The invention relates to the field of measurement, in particular to an equal-period fitting measurement method for the power factor of a short-circuit withstand strength test of a low-voltage electrical appliance product. Background technique [0002] For the short-circuit withstand strength test in the type test of low-voltage electrical products, both the International Electrotechnical Commission (IEC) and my country's national standard (GB) have clear regulations on the test power factor, so it is necessary to accurately measure and calculate the power of the short-circuit test system factor. The main difficulty of short-circuit test power factor measurement lies in the accurate measurement of power factor under the condition of large short-circuit current and short duration. It can be said that currently there is no power factor measurement method that can accurately determine the power factor of the short-circuit test system under different test c...

Claims

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Application Information

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Patent Type & Authority Patents(China)
IPC IPC(8): G01R21/00G01R31/12
CPCG01R21/006G01R31/12
Inventor 窦慧
Owner SHANDONG INST FOR PROD QUALITY INSPECTION
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