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TENTECH TM25t Grounding Resistance Meter

The TM25t is specially designed to test grounding resistance of power transmission towers, overcoming challenges posed by interconnected grounding wires. Conventional low-frequency earth meters often provide inaccurate readings because they measure the combined resistance of multiple towers. The TM25t uses a high-frequency (25 kHz) test current to isolate and accurately measure the resistance of a single tower’s grounding system without disconnecting the ground wire.

Ideal for harsh outdoor environments, this portable device ensures reliable, fast, and safe testing of tower grounding quality — critical for protecting transmission lines against lightning discharges.

Key Features

  • Measures earth resistance of individual electricity pylons

  • High-frequency operation (25 kHz) minimizes interference from adjacent towers connected by ground wires

  • Automatic 20 mA test current injection

  • Inductive component compensation via internal capacitor bank (max 4.2 μF, resolution 10 nF)

  • Accurate readings with ±2.5% accuracy

  • Large alphanumeric LCD with 4 lines and 20 characters, including large numbers for easy reading

  • Built-in thermal printer for immediate test reports

  • Stores up to 2,000 test results in internal non-volatile memory

  • Supports Modbus protocol for industrial integration

  • USB and Bluetooth connectivity for configuration, control, and data download

  • Compatible with PC software (TLogger) and Android app (TENTECH Remote Control) for remote operation and report generation

  • Robust and weather-resistant with IP65 rating (lid closed)

  • Rechargeable lithium-iron phosphate battery with included charger

  • Includes comprehensive accessories kit for field testing

Technical Specifications

Specification Details
Measurement Range 0 – 300 Ω
Operation Frequency 25,000 Hz (25 kHz)
Test Current 20 mA (automatic)
Inductive Compensation Internal capacitor bank, max 4.2 μF, resolution 10 nF
Measurement Accuracy ±2.5% of reading ±1 digit
Max Earth Resistance of Auxiliary Rods Current rod: 2000 Ω
Voltage rod: 2000 Ω
Display Alphanumeric LCD, 4 lines × 20 characters (large numbers)
Printer Built-in thermal printer
Memory Up to 2000 test readings
Protocol Modbus
Connectivity USB, Bluetooth
Safety Rating IEC 61010-1, CAT IV – 300 V
IP Rating IP65 (lid closed)
Operating Temperature -10°C to 50°C (14°F to 122°F)
Storage Temperature -25°C to 70°C (-13°F to 158°F)
Humidity 95% RH, non-condensing
Power Supply Rechargeable LFP battery, 12 V, 6000 mAh
Battery Charger 12 V, 2 A
Weight Approx. 4.9 kg (10.8 lbs)
Dimensions 345 × 272 × 159 mm (13.6" × 10.7" × 6.3")

Included Accessories

  • 8 × 50 cm steel core rods with copper coating

  • 6 × 2 m cables for auxiliary rods

  • Rod extractor tool

  • Shielded cables (70 m, 50 m, 30 m)

  • Cables for current and potential rods

  • Cable adapter for current electrode

  • AC adapter

  • Cable for tower electrode connection

  • USB cable

  • User guide

  • TLogger PC software (download)

  • TENTECH Remote Control Android app (download)

  • Carrying case for accessories

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