Earth Tester

Earth Tester (3)

Saturday, 08 August 2015 15:17 Written by


The transmission towers are electrically grounded by ground wires and due to the existence of this connection, any attempt to measure a tower ground resistance by any conventional earth tester leads to wrong results. To make this kind of test feasible, TM- 25R is the appropriate tool for a fast, safe and reliable grounding resistance measurement in each tower at charged transmission lines, without disconnecting the ground wire. The equipment only measures the ground resistance of the Surveyed Tower, including its base.


  • Intended for measurement of earth resistance of electricity pylons
  • Minimizes the influence of adjacent pylons, connected by the guard cable
  • Operation fraquency: 25 kHz
  • Resisteance reading: up to 300 Ω
  • Automatic current injection
  • Built-in memory and printer
  • Rechargeable battery


Parameters TM25R
Measurement Range 0 to 300 Ω
Test Current 20 mA automatic
Display Alphanumeric display (LCD)
Max. Earth Resistance Of Auxiliary Rods 2,000 Ω (current rod) , 2,000 Ω (voltage rod)
Power Supply Internal rechargeable battery
Operating Temperature -5°C to 50°C
Humidity Up to 95% RH (non condensing)
Equipment Weight 4.9 kg
Measurement Accuracy ± 2.5 % of reading ± 1 digit
Data Output USB
Built-In Memory It allows for the storage of 2,000 test readings in its internal NVRAM memory
Battery Charger 12 V - 2 A
Storage Temperature -15°C to 65°C
Dimensions 340 x 295 x 152 mm
Accessories Weight Approx. 16.5 kg



Wednesday, 12 August 2015 07:18 Written by


The MTD-20KWe 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.


  • 3½ digits display
  • Earth Resistence measurement
  • Spurious voltage measurement
  • Resolution: 0.01 Ω
  • Resistence reading: up to 20 kΩ
  • Audible signal indicates anomalies in the current circuit


Measurement ranges

Resistances: 0-20 Ω; 0-200 Ω; 0-2,000 Ω; 0-20 kΩ

Tension: 0-200 V~.


Resistances measurements:

± (2% of the measured value + 1% of the maximum value of the selected range).

Voltage measurements:

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

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 15 mA (Peak to peak).
Audible alarm It warns the operator in case that there are abnormalities in the current circuit, which make it difficult to obtain a reliable result.
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.
Saturday, 08 August 2015 15:24 Written by

EM 4058

The EM4058 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.

It is also suitable for soil resistivity measurements, in order to optimize the earth systems project. It is a fully automatic and easy-to-operate equipment. Before starting each measurement, the equipment will check that conditions are within appropriate limits and will notify the operator in case any abnormality turns up (too high interference voltage, too much resistance in test spikes, very low test current, etc). Then, it will look for the most suitable range and show measurement results in an alphanumeric display.

The EM4058 has a Frequency Scan feature that performs an earth resistance measure with all vailable frequencies automatically and calculates, displays and prints the average result besides the individual result of each frequency. Those results are saved on the internal memory. 

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


Parameters EM 4058 
Measurement ranges Resistance (Autoranging) - 0 – 20 KΩ, Resistivity 0 – 50 KΩm Voltage  0 – 60 V AC
Measurement Accuracy Resistance ± 2% of Reading ± 2 Digit Voltage ± 3% of Reading ± 2 Digit
Measurement Resolution Resistance - 0.01 Ω, Resistivity 0.01Ωm Voltage – 0.1 V
Operation Frequency 

270 Hz (resistance or resistivity measurement)

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

Power Supply  Internal Rechargeable LiFePO4 battery 
Operating temperature -10˚C to 50˚C
Equipment Weight Approximately 3 Kg 
Interface  USB 
Dimensions 274 x 250 x 124 mm