Source device and method for AC micro-current

Abstract

The invention relates to a source device and method for an AC micro-current, which solves the source problem of AC micro-current from 1mA to 10 [Mu]A (50Hz to 10kHz), and the measurement uncertainty reaches the order of 10[-5] to 10[-4]. The device includes an equivalent AC resistor-AC micro-current calibrator formed by a combination of a low noise wide-band amplifier and an AC resistive shunt. The measured AC micro-current is passed into the AC micro-current calibrator. The output voltage of the AC micro-current calibrator is measured by a high-accuracy AC voltmeter. The magnitude of the measured AC micro-current is obtained by converting the ratio of the measured voltage value to the equivalent AC resistance. The AC resistive shunt is calibrated by a calculable resistor. The low noise wide-band amplifier is verified by a magnification verification device. The AC voltmeter is calibrated by an AC standard voltage source.

Description

technical field [0001] The invention relates to the technical field of electrical measurement, in particular to an AC microcurrent traceability device and method. Background technique [0002] The minimum range of the existing high-accuracy digital multimeter for measuring AC current is 100 μA, which needs to be calibrated from 10 μA; the high-accuracy multi-function standard source can output 10 μA AC micro-current, and the standard value of the output needs to be determined through calibration; but currently There is no standard device for calibrating AC microcurrent below 1mA, and there is no accurate and reliable traceability method. [0003] At present, there are two ways to trace the source of AC current: [0004] One is the thermoelectric conversion method, that is, the effective value of the alternating current is compared with the standard direct current, and the magnitude of the alternating current is determined by the magnitude of the direct current. In the prio...

AI Technical Summary

Problems solved by technology

In the prior art, a thermoelectric converter is used as an AC-DC current conversion measurement device to realize a standard device for analog AC-DC current conversion measurement, but the problem existing in analog AC-DC current conversion measurement is that the input current must be above 10mA and less than The output voltage of the thermoelectric effect generated by the 10mA current is too small, the signal-to-noise ratio is poor, and the required accuracy cannot be achieved. Therefore, the thermoelectric conversion method cannot solve the traceability problem of the AC micro-current below 1mA

The AC resistance shunt is a resistor with small frequency error and can pass the rated current. Determining its frequency error is a current technical problem, and there has been no effective solution in China. Only NPL in the UK and PTB in Germany can provide AC resistance in the world. Calibration service

The input impedance of the AC voltmeter is usually 1MΩ. When measuring the AC microcurrent of 10μA, a 100kΩ resistor shunt is required. At this time, due to the shunt effect of the input impedance of the AC voltmeter, the measurement error reaches 10%. -5 to 10 -4 The magnitude of the traceability requirements is very different

[0006] Through the above analysis, it can be seen that the traceability of AC microcurrent is a difficult problem in the field of international electrical measurement. At present, there is no high-accuracy AC microcurrent calibrator in the world.

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