Grounded resistance measuring apparatus

Abstract

A measuring device which uses two linked switches to carry out detection for measuring device is featured as carrying out stray current and stray voltage measurement of the earth to have accurate measuring result for earthing resistance, carrying out detection for connection state of resistance measuring device to earthing electrode to avoid measurement error caused by break point in connection.

Description

technical field [0001] The invention relates to a ground resistance measuring device, in particular to a ground resistance measuring device. Background technique [0002] Such as figure 1 As shown, the grounding resistance measurement device in the prior art includes a current measurement circuit and a voltage measurement circuit. The current measurement circuit includes a power supply V1, a switch K1, an ammeter A, and current ground terminals C1 and C2. It starts from the power supply V1 and passes through the switch K1. , ammeter A, current grounding terminal C1, earth F, current grounding terminal C2, and finally return to the power supply V1 to form a current loop; the voltage measurement loop includes power supply V2, double switching switches K2, K3, variable resistor R, voltmeter V , Voltage grounding terminals P1 and P2, wherein the fixed terminals of the double switching switches K2 and K3 are both 0 terminals. [0003] When preparing for the measurement, there i...

AI Technical Summary

Problems solved by technology

[0005] The weak point in this prior art is: 1, because this current loop can't measure the stray current of the earth, then contain stray current in the electric current value that reads out when measuring, but in calculation or do not subtract This stray current value, or only the stray current can only be estimated, will bring great errors to the calculation results; 2. Since the connection between the ground electrode and each ground terminal is active during the ground resistance measurement, It is often easy to disconnect during operation, so the connection must be detected, but this function is obviously not available in the prior art. If the P2 point is disconnected, but because the P1 point has a potential, and the resistance R is in the power supply V2 The contact with the voltmeter V will also have a potential under the action of the voltmeter V, and the two potentials may produce a potential difference, causing the voltmeter V to still have a reading, but the reading at this time is not the stray voltage value of the earth, so the prior art does not It has connection detection function; 3. When preparing for measurement, it is necessary to adjust the voltmeter V, but since the stray voltage of the earth is not directional and has no periodicity, it may appear during the adjustment. It is in the same direction as the power supply V2, and the stray voltage is reversed to the power supply V2 during measurement, which brings a large error to the measurement, and the operation is also quite cumbersome; 4. The voltmeter V and ammeter in the prior art All of them use needle-type instruments, and their readings are often different due to different testers, so the error of the calculation results is also large.

Images