High Frequency Earth Ground Tester

  • Intended for measurement of earth resistance of electricity pylons
  • Minimizes the influence of adjacent pylons, connected by the guard cable
  • Operation frequency: 25 kHz
  • Resistance reading: up to 300 Ω
  • Automatic current injection
  • Built-in memory and printer
  • Rechargeable battery
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Testing of the power transmission towers grounding (G) quality poses a serious problem as they are all electrically interconnected by means of Ground Wires which act as lightning rods, protecting the lines from atmospheric discharges. Due to the existence of this connection, any attempt to measure a tower grounding (G) resistance using a conventional earth meter leads to wrong results as what is really being measured is all the shunt towers grounding (G) resistance (or, more precisely, its impedance at low frequency).

To make this kind of test feasible, which is of vital importance to ensure the transmission of the electrical power without interruptions, TENTECH TM25t grounding resistance meter for high frequency has been developed. This is the appropriate tool for a fast, safe and reliable grounding resistance measurement in each tower of a working line transmission, without disconnecting the ground wire.

Its operation is based on the use of a high-frequency measurement current (25 kHz), for which ground wire inductive impedance - taking into account a typical length span - is reasonably high, making it possible to reduce the effect of the adjacent towers under measurement. The equipment only measures the ground resistance of the surveyed tower, including its base. The extensive G systems, such as meshes, buried wires, metal pipes, etc, are measured only considering the closest section to the connection point, so that the measured value represents the performance against a pulse signal similar to an atmospheric discharge. Thus, values that better represent the system capacity to ground lightning currents than the ones obtained with low frequency conventional equipments, even when disconnecting the ground wire, are obtained. TM25t is a strong equipment, easy to carry, resistant to the hard weather and geographical features of the tropical and high-mountain regions, that is why it is described as an excellent product for field works under the most severe environmental conditions.

Technical specifications

Measurement ranges

0 - 300 Ω

Operation frequency

25,000 Hz

Test current

20 mA automatic

Inductive component compensation

• Through bank of capacitors integrated to the equipment
• Maximum capacity: 4.2 μF
• Resolution: 10 nF

Measurement accuracy

± 2.5 % of reading ± 1 digit

Max. earth resistance of auxiliary rods

2,000 Ω (current rod)
2,000 Ω (voltage rod)


Alphanumerical LCD display, 4 lines / 20 characters (Big Number)


Built-in thermal printer

Built-in memory

It allows for the storage of 2,000 tests readings in its internal NVRAM memory




For configuration, control and download the stored values


For configuration, control and download the stored values

Overvoltage protection

CAT IV - 300 V


IEC 61010-1

Desktop Software (PC/Notebook)

TLogger software: for remote control, allowing to configure, run tests and generate reports

Android App (Smartphone/Tablet)

TENTECH Remote Control app: for remote control, allowing to configure, run tests and generate reports

IP rating

IP65 (with closed lid)

Operating temperature

14 °F to 122 °F (-10 °C to 50 °C)

Storage temperature

-13 °F to 158 °F (-25 °C to 70 °C)


95 % RH (non condensing)

Power supply

Internal rechargeable battery (LFP 12 V 6000 mA)

Battery charger

12 V - 2 A

Equipment weight

Approx. 10.80 lb (4.9 kg)


13.6" x 10.7" x 6.3" (345 x 272 x 159 mm)

Included accessories

8x 19.6" (50 cm) long steel core rods with copper coating
6x 6.5 ft (2 m) cables for interconnection of extra auxiliary rods
Rod extractor
229.6 ft (70 m) shielded cable
164 ft (50 m) shielded cable
98.4 ft (30 m) cable to current rod
229.6 ft (70 m) cable to auxiliary potential rod
164 ft (50 m) cable to auxiliary potential rod
Cable adapter for current electrode
AC Adapter
Cable for connection to the unknown electrode (Tower)
USB cable
User guide
TLogger software (download)
TENTECH Remote Control app (download)
Case to carry accessories


Remote control by Android device

This instrument has Bluetooth® interface and can be controlled remotely via an Android™ smartphone / tablet running the TENTECH's remote control application.

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Go to Google Play Store

• Android™ and Google Play™ Store are trademarks of Google, Inc.
• Bluetooth® is a registered trademark of Bluetooth SIG, Inc. worldwide.

Rechargeable battery (LiFePO4)

Expected lifetime
2,000 charge / discharge cycles (average).

Low self-discharge
When the equipment is not in use, battery charge decreases with time at a much lower rate than other battery technologies.

In contrast to other lithium battery technologies commonly used, LFP batteries are thermally and chemically stable, significantly improving battery safety.
Company history
13 Years


Customer service
Phone: +1 305 938 0389

Phone: +1 305 938 0389