I. Introduction

HZJD-470A digital grounding resistance tester is designed and manufactured according to the new lightning protection grounding resistance detection standard. The short-circuit test current can reach 20mA. The precision 3-wire method or simple 2-wire method can be used to measure the grounding resistance, and FFT (fast Fourier transform) is introduced. Technology, using digital filtering algorithm, has unique anti-interference ability and environmental adaptability, and has strong consistency in repeated tests. It is widely used in grounding resistance and grounding voltage measurement of electric power, telecommunications, meteorology, oil field, construction, lightning protection and industrial electrical equipment, etc.

The instrument has a unique line resistance calibration function, which is more accurate in the measurement of low-value grounding resistance on site, and can avoid errors caused by changes in line resistance caused by long-term use of the test line; it can avoid errors caused by the test line not being fully inserted into the instrument interface or poor contact. Error; it can avoid the error caused by the user changing or lengthening the test line.

The instrument is composed of host, test line, auxiliary ground rod, data software, communication line and so on. The host adopts an integrated hand-held design, which has low density, light weight, superior strength, rigidity, hardness, wear resistance, heat resistance and insulation performance, ensuring high precision, high stability and high reliability of various environmental tests . The main unit has a large LCD display with backlight and bar graph instructions, which are clear at a glance, and can store 300 sets of data. Through the data software, functions such as reading, consulting, saving, reporting, and printing of historical data can be realized.