Measurement method for cable insulation leakage current

Abstract

The invention relates to a cable insulation leakage current measurement technology, in particular to a method which measures the cable insulation leakage current through dielectric loss tangent. Taking the A-phase current measurement as an example, the invention adopts a mirror current source test technology to divide a sensor for testing the A-phase current into two parts CT1 and CT1` in the new test method; the current flowing directions of the CT1 and the mirror CT1` are made symmetric in advance during the production, namely, Ict1 is equal to Iag plus Iaf, Ict1` is equal to -(Iaf plus (2Iag)), and Io is equal to Ict1 plus Ict1` and also equal to-Iag; through the mirror current source technology, the needed current component -Iag (the leakage current component corresponding to A) is measured, while IBG and Icg are also measured based on the same principle. The method has the advantages that the direct method is used to measure each phase leakage current, and the monitoring way is easy to realize, thereby complementing the existing detection performances and improving the reliability and accuracy of the monitoring system.

Description

technical field [0001] The invention relates to the measurement technology of the cable insulation leakage current, in particular to a method for measuring the cable insulation leakage current by the dielectric loss tangent method. Background technique [0002] Cable transmission projects are mainly underground projects, and the surface cannot be observed in real time, so it is particularly important to be able to monitor its "insulation degree"; each cable carries a certain number of users, and sudden power failures on the line will cause huge economic losses and bad social impact. The feature of applying on-line monitoring and fault diagnosis technology is that it can monitor and judge the running status of power cables continuously or at any time, which can avoid the shortcomings of previous periodic preventive tests, and make the existing equipment operation mode change from "due maintenance" Transitioning to the era of "repair should be repaired", the development and a...

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Problems solved by technology

[0031] Although the measurement points of leakage current measurement method 2 have found the required Iag, Ibg and Icg, it has brought new problems. The measured value also has the current value of the electrical load of each phase, how to eliminate the electrical load of each phase The load current value is the main target of the newly designed current sensor

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