Microcurrent detecting system in dielectric medium insulation diagnosis

Abstract

The invention discloses a microcurrent detecting system in dielectric medium insulation diagnosis. The system comprises an I-V conversion amplifying circuit, a temperature drift inhibiting circuit, an instrument amplifying circuit and a power source filter circuit, and a grounded metal shielding box is arranged for the circuit. The microcurrent detecting system is characterized in that microcurrent is converted into voltage through the I-V conversion amplifying circuit and subjected to primary amplifying, the microcurrent is further amplified through the instrument amplifying circuit and output, the temperature drift inhibiting circuit offsets temperature drift of an operational amplifier in the I-V conversion circuit, the detecting precision is improved, the influence of power source fluctuation and harmonic waves on the detecting precision can be reduced through the power source filter circuit, and the influence of the external electromagnetic environment can be reduced through the grounded metal shielding box. The I-V conversion amplifying circuit comprises a T type feedback circuit and a range changing switching circuit, and therefore input impedance is increased, and the detecting range is widened. According to the module, the microcurrent detecting precision is high, and the detecting range is wide. The system has high application value.

Description

technical field [0001] The patent of the present invention relates to a micro-current detection system used in dielectric insulation detection. Background technique [0002] In dielectric insulation detection, it is necessary to apply a high voltage to the dielectric, then detect the weak current flowing in the dielectric, and analyze the current in the frequency domain or time domain. Since the current is often in the microampere or picoampere level, it is extremely important to detect and amplify the microcurrent without distortion. At present, there are mainly methods for microcurrent detection. [0003] The large resistor negative feedback detection method makes a weak current flow through a resistor with a large resistance value, thereby generating a measurable voltage at both ends of the resistor to realize micro-current detection. However, this method has too high a requirement on the accuracy of the resistance, and the greater the resistance, the worse the stability...

AI Technical Summary

Problems solved by technology

[0005] Sampling resistance differential detection method, the sampling resistance differential detection method has the advantages of simple structure and can effectively remove common-mode interference, but the sampling resistance and the capacitive sample are connected in series in the circuit, and the results need to be further converted when measuring the loss curve, which brings new problems to the test. inconvenient

[0006] The above methods all have obvious shortcomings. In order to make up for the shortcomings of the existing measurement methods, a new micro-current detection circuit is proposed.

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