Double-end grounding loop resistance and ground screen resistance measuring device and method

Abstract

The invention discloses a double-end grounding loop resistance and ground screen resistance measuring device and method.The device comprises a measuring device for outputting constant current to a measuring loop; the measuring loop comprises a measured branch, a grounding bar and a ground screen which are connected in series; the grounding bar is provided with a sampling clamp for measuring voltage signals of the grounding bar; and the output end of the sampling clamp is connected with the input end of the measuring device. According to the method, the sampling clamp and the measuring device are used for measuring the voltage of the grounding bar to obtain the shunt proportion according to the voltage proportion, and then the measured branch resistance is calculated. According to the invention, under the condition that the grounding wire is not dismounted, the actual current value flowing through each branch can be accurately measured, so that the loop resistance or the ground screen resistance of each branch can be accurately measured, and the detection accuracy and the working efficiency are improved.

Description

technical field [0001] The invention relates to the technical field of power supply detection, in particular to a device and method for measuring the resistance of a double-terminal grounding loop and ground grid. Background technique [0002] With the promotion of GIS (Gas Insulated Substation), disconnectors and circuit breakers will automatically enter the double-terminal grounding state in the state of power outage maintenance. Due to the multiple current loops, the error of traditional loop resistance measurement will be too large; In the ground network resistance measurement of multi-point grounding, multiple current branches will also be formed, and a similar situation will appear. [0003] For the loop resistance or ground grid resistance of double-ended grounding, double-ended grounding leads to multiple branches connected in parallel. To measure the resistance value of each branch, the key is to obtain the current value of each branch. There are currently two solut...

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Problems solved by technology

[0002] With the promotion of GIS (Gas Insulated Substation), disconnectors and circuit breakers will automatically enter the double-terminal grounding state in the state of power outage maintenance. Due to the multiple current loops, the error of traditional loop resistance measurement will be too large; In the ground network resistance measurement of multi-point grounding, multiple current branches will also be formed, and a similar situation will appear

[0003] For the loop resistance or ground grid resistance of double-ended grounding, double-ended grounding leads to multiple branches connected in parallel. To measure the resistance value of each branch, the key is to obtain the current value of each branch. There are currently two solutions: 1) Use large current measurement: This method is suitable for the difference of at least 1 order of magnitude in the resistance of the parallel branch circuit. With a current of 300A or more, the measurement result will be close to the resistance of the branch circuit under test; it is not easy to judge whether the application conditions are satisfied. Results are always subject to error and their range of application is limited

2) Use AC and DC current clamps to measure the current of one or more branches, so as to obtain the actual current value of the measured branch, and then calculate the resistance value; its measurement accuracy is limited by the measurement accuracy of the current clamp, and even some on-site It is impossible to provide the current clamp measurement site, or there are too many branches, and the simultaneous measurement of the current clamp becomes complicated and difficult to achieve

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