Portable Digital Ground Resistance Tester

The digital ground resistance tester is meticulously designed and manufactured for on-site measurement of ground resistance. Utilizing the latest digital and microprocessor technology, it employs the 3-wire or 2-wire method to measure ground resistance. With unique wire resistance verification functionality, anti-interference capability, and environmental adaptability, it ensures high precision, stability, and reliability for long-term measurements. It is suitable for power, telecommunications, railways, communications, mining, and other sectors to measure the ground resistance of various installations as well as low-resistance conductor resistance values. This instrument can also measure soil resistivity and ground voltage.

The digital ground resistance measuring instrument builds upon its predecessors by discarding the traditional manual hand-cranked power generation method. It incorporates large-scale integrated circuits and utilizes DC/AC conversion technology to combine the three-terminal and four-terminal measurement methods into a single new model of ground resistance measuring instrument.

The working principle involves converting DC to low-frequency constant AC current via an internal DC/AC converter. This current flows through a loop formed by the auxiliary grounding electrode C and the object under test E, generating an AC voltage drop across the object under test. The voltage drop is sent to an AC amplifier via the auxiliary grounding electrode P, amplified, and then detected and displayed on the meter. With the help of a range switch, three different measurement ranges can be obtained: 0~2Ω, 0~20Ω, and 0~200Ω.

(1) Structurally, it uses high-strength aluminum alloy for the casing. Electrically, to prevent power frequency and radio frequency interference, it employs a phase-locked loop synchronous tracking detection method combined with a switched capacitor filter, giving the instrument excellent anti-interference capabilities.

(2) It uses DC/AC conversion technology to convert DC into low-frequency constant AC current for ease of measurement.

(3) It allows the auxiliary grounding resistance to vary between 0～2KΩ (RC) and 0～40KΩ (RP) without affecting the measurement results.

(4) This instrument does not require manual balance adjustment. It features a 3½-digit LCD display and can measure low-resistance conductor resistance, soil resistivity, and AC ground voltage in addition to ground resistance.

(5) If the test circuit is open, the meter displays "1" to indicate overflow, which aligns with conventional measurement practices.