The Sonel MRU-200-GPS earth resistance and soil resistivity meter is a versatile meter for earth resistance and soil resistivity measurements. The device allows the use of all known earth resistance measurement methods. This renders it an unrivalled measuring instrument in its category and definitely makes it stand out from other devices of its kind. Sonel MRU-200-GPS allows you to perform tests with the 3-pole and 4-wire method, using additional clamps (multiple earthing), as well as the two-clamp method and impulse method (earth impedance measurement).

The application of the two-core measurement method allows, under certain conditions, to perform earth resistance measurements without the use of auxiliary probes which are driven into the ground. The impact method, on the other hand, is used for diagnosing lightning protection earthing, but can also be used to measure extensive, multiple and connected earthing (including underground) without interfering with the circuit. With the use of the impact method it is possible to carry out measurements in accordance with EN 62305 - the need to measure earth impedance. It is worth noting that the instrument also has a built-in GPS receiver, which allows for recording the result along with the coordinates of the location. An additional function of the meter is the possibility of carrying out measurements of soil resistivity, continuity of protective and equalising connections and, with the use of clamps, also leakage or fault currents.

The high class of the device is confirmed by the excellent accuracy of the result it produces. The meter makes measurements in accordance with the EN 61557 standard starting from 0.100 Ω.

Accessories included:

1pcs - N-1 Transmitting clamp (Φ=52 mm, incl. 2-wire cable)
1pcs - Test lead 1 kV (banana plugs) red 1.2 m
1pcs - Test lead 2.2 m CAT III/1000V CAT IV/600V (banana plugs) black
1pcs - Test lead 25 m for earth resistance measurements (on a reel, banana plugs) blue
1pcs - Test lead 50 m for earth resistance measurements (on a reel, banana plugs, shielded) yellow
1pcs - Cable for battery charging from car cigarette lighter socket (12 V)
1pcs - C-3 Current clamp (Φ=52 mm)
1pcs - Test lead 25 m for earth resistance measurements (on a reel, banana plugs) red
1pcs - AKU-07 NiMH battery 4.8 V 4.2 Ah
1pcs - Z-7 Power supply adapter
4 pcs - Earth contact test probe (rod), 30 cm
1pcs - XL-3 Hard carrying case
1pcs - K-02 Crocodile clip, red, 1 kV, 20 A
1pcs - Cramp with banana socket
1pcs - USB cable
1pcs - K-01 Crocodile clip, black, 1 kV, 20 A
1pcs - L-2 Hanging straps

Measurement methods:

Impulse method - measurement of lightning protection systems with a measuring impulse ramp of 4/10 μs, 8/20 μs, 10/350 μs
3-pole and 4-wire method - measurement of earthing systems using auxiliary probes
3-pole method with clamp - measurement of earthing systems with multiple earth electrodes
Two-clamp method - measurement of earthing system when the auxiliary probes cannot be used
Earth resistivity - Wenner method
Resistance of earth and compensatory conductors measured using current ≥200 mA with auto-zero function - meets the requirements of EN 61557-4
Measurement of leakage current

Additional featuresL

Built-in GPS receiver - recording results with location coordinates
Measurement of resistance of auxiliary electrodes RS and RH
Measurement of interference voltage
Measurement of interference frequency
Measurement in the presence of interference voltage generated by power networks with frequency of 16 2/3 Hz, 50 Hz, 60 Hz, 400 Hz
Selection of maximum measuring voltage (25 V and 50 V)
Automatic calculation of soil resistivity in ohm-meters (Ωm) and ohm-feet (Ωft)
Memory of 990 measurement results (10 banks of 99 cells each)
Calibration of clamp used
Real time clock (RTC)
Data transmission to the computer and mobile devices
Battery indication

Application:

MRU-200-GPS meter was created for the most difficult working conditions. It generates a measuring current exceeding 200 mA, which provides effective measurements of grounding of energy objects such as transformer stations and power stations.
Thanks to the methods using clamps, it is not necessary to disconnect the control connectors, which is sometimes a very tedious operation. This plays a special role when performing works on objects exposed to weather conditions, where the connecting elements are sometimes corroded or tarnished.
The graphical user interface provides clear readings and explicit messages. This translates into quick, trouble-free service.

Impulse method:

MRU-200-GPS may be used to test earthing of lightning protection systems, as this meter is able to simulate the conditions occurring during a lightning strike - it generates current with a standardized pulse leading edge and a time to half-peak. Available impulse ramps include 4/10 μs, 8/20 μs, 10/350 μs.

Compatible with ERP-1 adapter:

ERP-1 adapter allows user to test earthing systems using flexible clamps. This is particularly useful, e.g. in case of lattice towers - there is no need to switch off the line or disconnect control connectors. Proprietary algorithm allows user to check the current direction in the individual measurements and facilitates damage detections, e.g. corroded steel strip (hoop).

Capabilities:

The measuring methods available in the device allow for comprehensive control of working and protective grounding. The calibration function of the test leads eliminates the influence of their resistance on the result. However, this is just the beginning.

The four-lead method provides very accurate measurement of the expected small values of resistance - eliminates the resistance of the test leads connecting the meter to grounding.
Measurement of the continuity of protective connections and equipotential bondings with a current exceeding 200 mA meets the requirements of EN 61557-4 standard.
Before performing the measurement, the meter checks whether the tested object is a subject to excessive interference voltage, which may indicate additional problems.

Memory and results:

The results can be saved to the device's memory. It is divided into 10 banks of 99 cells, each corresponding to one measurement. These results can be easily transferred to the Sonel Reader software for archiving or subsequent analysis and research.
Bluetooth wireless interface may be used to transfer measurement results to PC software or to a mobile phone with dedicated app - Sonel MRU Mobile. This provides not only data archiving function, but further data transfer - directly from the measurement site via an e-mail.

Datasheet MRU-200 / 200-GPS EN

Sonel WMUSMRU200GPSXL3C3N1 MRU-200 GPS Earthing Resistance & Soil Resistivity Meter