Assessment uncertainty of the tests pace distinctive ability of the computerized testing system

Abstract

Problem of developing a metrological instrument for measuring active power in the frequency range from 0,01 to 10 MHz is considered in the article. Constructing of such an instrument must meet a high requirement of channels phase characteristics at a low power factor at measuring active power against the background of large reactive one.In today's electric power converters, the main losses that determine the efficiency factor are shifted from semiconductor keys to reactive elements. In order to optimally design such reactive elements, it is necessary to be able to analyze the components of the loss [1]. Such an instrument will measure the loss power (active power) in a variety of reactive elements, for example, chokes used in pulsed energy converters [2].In currently available power analyzers and wattmeter, there are significant errors in the frequency range above 1 MHz, which makes it difficult to meet the above objectives [3].An example of the harmonic signal components effect and errors analysis caused by the measurement channels phase shifts in the wattmeter is described in the article.At high frequencies, the wattmeter channels become very sensitive to phase errors. It is necessary to minimize links that cause phase shifts. In this connection, it is important to construct correctly wattmeter input links and to make such a transformation, which will provide operations with signal rms modules without taking into account phase shifts. In order to solve this problem, it is advisable to use a broadband wattmeter of transient power with the correction of the error from its own consumption, described in [6 - 8], to minimize losses and optimize the system.The wattmeter of this design gives the exact value of the measured power on the load, regardless the actual consumption of the input device. The value of the input device elements can be optimized by the criterion of maximum broadband, since the error from its own consumption is taken into account. In the scheme one low-level shunt is used. It reduces wattmeter cost and also reduces voltage conversion channel additive errors.The wattmeter basic error is the error of the low-ohm shunt. To extend the frequency range, it is advisable to use coaxial or tri-axial shunts. It is expedient to use thermocouples measuring device to determine precisely the active component in a wide frequency range.