Earth Tester

Earth Tester (3)

Wednesday, 12 August 2015 07:18 Written by


The MTD20KWR digital earth tester allows for the measurement of Earth Resistances and Soil Specific Resistivity, and also the spurious voltages caused by parasitic voltages present in the soil.

This equipment is suitable for fast and easy measurement of the grounding resistance in house and industrial buildings, hospital installations, lightning rods, antennas, substations, etc. Soil resistivity measurement allows for soil stratification in order to optimize the most complex grounding systems engineering.

Its state-of-the-art system of active and passive filters provides it with high immunity to electric interferences, making it possible to obtain reliable measurements even in the presence of spurious voltages, such as the ones that can be found in some urban areas and near primary substations.

A 1,470 Hz internal generator injects alternated current on the soil through an auxiliary rod. The voltage generated over the earth resistance is measured by the apparatus, and the resistance value is evaluated. The test current is automatically regulated.It has abnormalities indications on the display which advises the operator when the generated current is not enough to carry out reliable measurements.Because of its wide range of measurement (from 0.01 Ω up to 20 kΩ), this equipment allows for reliable testing in all kinds of soils, including those that offer very high resistivity.

This earth tester is supplied with a rechargeable internal battery. The smart charger is microprocessor-controlled, and can be powered from a 12 V car battery (or a similar one).

It has a sturdy, easy and safe to carry cabinet, with IP65 protection level (closed lid). It is suitable to work under adverse geographical and environmental conditions, with extreme temperatures in cold or tropical regions and in high mountain areas, showing a reliable performance in the field.


  • Digital and automatic
  • Earth resistance measurement
  • Ground resistivity (Wenner’s method)
  • Spurious voltage measurement
  • High spurious voltage rejection
  • Indication of anomalies in the current circuit
  • 0.01 Ω resolution
  • Up to 2 kΩ resistance range
  • Rechargeable NiMH battery
  • IP65 rated (with closed lid)
  • Graphic display (128 x 64 px)


Specifications   MTD20kWr
Measurement ranges

Resistance: 0-20 kΩ

Tension: 0-200 V~.


Resistance measurements:

± (2% of the measured value ± 2 digits

Voltage measurements:

± (2% of the measured value ± 2 digits)

Reading resolution

0.01 Ω in the resistance measurement. 

0.1 V in the voltage measurement.

Output power and current The output power is less than 0.5 W, and the output current is limited to less than 10 mA (Peak to peak).
Battery charger AC adapter 12 V - 1 A
Tuesday, 28 July 2020 12:32 Written by

EM 4058

The EM-4058 earth tester is a digital, microprocessor controlled instrument that allows to measure the earth resistance and ground resistivity (using Wenner´s method), as well as to detect parasitic voltages present in the ground. This instrument is suitable to measure earth systems in power substations, industries, distribution networks, etc., according to IEC 61557-5.

In order to conveniently test the earth system, EM4058 allows to perform measurements using the test current which frequency may be operator-selected (270 Hz, 570 Hz, 870 Hz, 1170 Hz or 1470 Hz). On one hand, the lowest frequency will allow to analyze the earth system behavior related to fault currents of industrial frequency, while on the other hand, the measurement performed with the highest frequency will best show the behavior in connection with electrical currents caused by lightning and will offer a very high immunity related to interference voltages that are usually present in soils, specially near substations.

The instrument has four ranges that are automatically selected, covering measurements from 0.01 Ω up to 20 kΩ, which allows to obtain very accurate measurements for any kind of soils. During ground resistivity measurement, the operator may indicate the distance between spikes in order for the equipment to apply Wenner's formula and to show the resistivity value directly.


  • Earth resistance measurement
  • Ground resistivity (Wenner's method)
  • High spurious voltage rejection
  • Spurious voltage measurement
  • Measure with multiples frequencies (270 Hz, 570 Hz, 870 Hz, 1170 Hz, 1470 Hz)
  • 0.01 Ω resolution
  • Up to 20 kΩ resistance range
  • Remote control through an Android App
  • Auto-range
  • Built-in memory
  • Built-in printer
  • USB interface


Measurement ranges

Resistances: 0-20 Ω; 0-200 Ω; 0-2,000 Ω; 0-20 kΩ (Auto-ranging)

Resistivity :  0- 50 kΩm (auto ranging)

Voltage: 0-60 V~


Resistance & Resistivity measurements:

R ≤ 2 kΩ: ± (2% of the measured value ± 2 digits).
R > 2 kΩ: ± (5% of the measured value ± 2 digits).

Voltage measurements:

± (2% of the measured value + 1% of end of scale value).

Reading resolution

0.01 Ω in the resistance measurement;

0.01 Ωm in the resistivity measurement;

0.1 V in the voltage measurement.

Output Current The short-circuit current is limited to less than 20.0 mARMS (according the IEC 61557-5 - 4.5).
Operation Frequency

270 Hz (resistance or resistivity measurement)

570 Hz, 870 Hz, 1170 Hz or 1470 Hz (resistance measurement)

Max. variation: ± 1 Hz (both cases).

Battery charger A smart, microprocessor controlled, circuit adjusts the battery charge to the optimised parameters in order to ensure the maximum service life. It is supplied by means of an external AC adapter (provided with the equipment) or from a 12 V car battery.
Tuesday, 28 July 2020 13:05 Written by


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.


  • 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 compensation of inductive component
  • Automatic current injection
  • USB interface
  • Built-in memory and printer
  • Rechargeable LFP battery


Specifications    TM25t
Measurement ranges

0 - 300 Ω


± 2.5 % of reading ± 1 digit

Operating Frequency 

25000Hz / 25kHz

Test Current 20mA automatic

Modbus,USB or Bluetooth 

Battery charger 12 V - 2 A

 -5°C to 50°C. (Operating)

-25°C to 70°C (Storage) 

Up to 95% RH (non condensing)


4.9 Kg (Approx)


345 x 272 x 159 mm