The Sonel MRU-30 uses most known methods of earth resistance measurements. Tests can be performed using the 3-pole, 4-pole, 3-pole with auxiliary clamp and also, additionally, the MRU-30 employs the two clamp method of measurement, without the use of auxiliary test rods which can't be used in some situations. Complementary features of the MRU-30 are measurements of soil resistivity, continuity measurement of protective and equipotential conductors and, using clamps, leakage currents and interference voltages.
- Robust and weatherproof (IP65) - no ingress of dust, water protected by a nozzle against enclosure from any direction.
- Ergonomic casing - small and handy casing to make the measurements more convenient than before.
- Built-in rechargeable battery - saving time to replace flat batteries; can be recharged from Power Bank and Cigarette Lighter Socket!
- Clear on-screen notes - displayed on screen before and after the measurement to alert user of possible dangers and irregularities.
- Many measurement methods available in a small, portable casing.
Virtual instrument application of Sonel MRU-30
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Measurements:
- earth ground resistance using auxiliary electrodes,
- earth ground resistance using auxiliary electrodes and clamp (for measurements of multiple earthing),
- earth ground resistance using double clamps (for measurement of earthing when it is impossible to use auxiliary electrodes),
- ground resistivity (Wenner method),
- continuity of equipotential bondings and protective
- conductors (meeting the requirements IEC 60364) with auto-zero function – with current 200mA.
Additionally:
- measurement of resistance of auxiliary electrodes RS and RH
- measurement of interference voltage
- measurement in the presence of interference voltage in the power network at frequency 50Hz, 60Hz,
- selection of maximum measuring voltage (25V and 50V)
- selection of the distance between test electrodes in meters (m) and feet (ft)
- memory storage of 990 measurements (10 banks of 99 cells each)
- calibration of clamp used
- data transmission to the computer (USB)
- indication of battery state
Measurement of interference voltage UN (RMS)
| Range | Resolution | Accuracy |
| 0 to 100 V | 1 V | ±(10% m.v. + 1 digit) |
Measurement of continuity of equipotential bondings and protective conductors (Rcont)
measurement range to IEC 61557-4:2007: 0,13 Ω...1999 Ω
| Range | Resolution | Accuracy |
| 0.00 to 9.99 Ω | 0.01 Ω | ±(2% m.v. + 3 digits) |
| 10.0 to 99.9 Ω | 0.1 Ω | |
| 100 to 1999 Ω | 1 Ω |
• measurement current: under short circuit >200mA
• frequency of measurement current: 125 Hz (for networks 50 Hz) and 150 Hz (for networks 60 Hz)
Measurement of earthing resistance (method 3- and 4-pole)
measurement range to IEC 61557-5:2007: 0.53 Ω to 9999 Ω (for 50 V)
| Range | Resolution | Accuracy |
| 0.00 to 19.99 Ω | 0.01 Ω | ±(3% m.v. + 3 digits) |
| 20.0 to 199.9 Ω | 0.1 Ω | |
| 200.0 to 1999 Ω | 1 Ω | ±5% m.v. |
| 2000 to 9999 Ω | 1 Ω | ±8% m.v. |
• measurement current: under short circuit >20 mA,
• voltage on open terminals: selectable 25 V AC or 50 V AC,
• frequency of measurement current: 125 Hz (for networks 50 Hz) or 150 Hz (for 60 Hz).
Measurement of multiple earthing esistance with using the clamp and auxiliary electrodes (3p + clamp)
| Range | Resolution | Accuracy |
| 0.00 to 19.99 Ω | 0.01 Ω | ±(3% m.v. + 3 digits) |
| 20.0 to 199.9 Ω | 0.1 Ω | |
| 200 to 1999 Ω | 1 Ω | ±5% m.v. |
| 2000 to 9999 Ω | 1 Ω | ±8% m.v. |
• voltage on open terminals: selectable 25 V AC or 50 V AC,
• measurement current: under short circuit >20 mA,
• frequency of measurement current: 125 Hz (for networks 50 Hz) and 150 Hz (for networks 60 Hz)
Measurement of resistance of auxiliary electrodes RH i RS
| Range | Resolution | Accuracy |
| 0 to 999 Ω | 1 Ω |
±(5% m.v.+ 8 digits) |
| 1.00k to 9.99 kΩ | 0.01 kΩ | |
| 10.0k to 19.9 kΩ | 0.1 kΩ |
Measurement of multiple earthing resistance with using double clamps
| Range | Resolution | Accuracy |
| 0.00 to 19.99 Ω | 0.01 Ω | ±(10% m.v. + 8 digits) |
| 20.0 to 99.9 Ω | 0.1 Ω | ±(20% m.v. + 3 digits) |
• frequency of measurement current: 125 Hz (for networks 50 Hz) and 150 Hz
(for networks 60 Hz)
Measurement of ground resistivity
Measurement method: Wenner, ρ=2πLRE
| Range | Resolution | Accuracy |
| 0.00 to 9.99 Ωm | 0.01 Ωm | depending on measurement
accuracy RE with 4p method, but not less than ±1 digit |
| 10.0 to 99.9 Ωm | 0.1 Ωm | |
| 100 to 999 Ωm | 1 Ωm | |
| 1.00 to 9.99 kΩm | 0.01 kΩm | |
| 10.0 to 99.9 kΩm | 0.1 kΩm | |
| 100 to 999 kΩm | 1 kΩm |
L – distance between probes: 1 to 50 m or 1 to 150 ft
Electric security:
- type of insulation: double, according to EN 61010-1 i IEC 61557,
- mesurement category: CAT III 300V wg EN 61010-1,
- protection class acc. to EN 60529: IP65,
Rated operational conditions:
- operation temperature: 14F to 131F / -10 to +55°C,
- storage temperature: -4F to 176F / -20 to +80°C,
- humidity: 20 to 90%,
Other technical data:
- LCD display: segment, backlit,
- dimensions: 7.87" x 5.90" x 2.91" / 200x150x74 mm.