Sonel MRU-120 User Manual
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Sonel MRU-120 User Manual

Earth resistance meter
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  • Page 2 MRU-120 – USER MANUAL...
  • Page 3 USER MANUAL EARTH RESISTANCE METER MRU-120 SONEL S. A. Wokulskiego 11 58-100 Świdnica Version 2.8 27.07.2021...
  • Page 4 The MRU-120 meter is a modern, easy and safe measuring device. Please acquaint yourself with the present manual in order to avoid measuring errors and prevent possible problems related to opera- tion of the meter. MRU-120 – USER MANUAL...

  • Page 5: Table Of Contents

    6.4 Charging of accumulators ..................34 6.5 Discharging of accumulators .................. 35 6.6 General principles regarding using Ni-MH accumulators ........36 7 Cleaning and maintenance ................37 8 Storage ......................37 9 Dismantling and disposal ................37 MRU-120 – USER MANUAL...
  • Page 6 4P, R 3P+C) ....42 11 Accessories ....................42 11.1 Standard accessories ..................... 42 11.2 Optional accessories ....................43 12 Positions of the meter’s cover ..............44 13 Manufacturer ....................44 14 Laboratory services ..................45 MRU-120 – USER MANUAL...

  • Page 7: Safety

     The MRU-120 meter has been designed for the purpose of measurements of earth connection and equipotential bonding, ground resistivity, as well as clamps current measurements. Any ap- plication that differs from those specified in the present manual may result in a damage to the de- vice and constitute a source of danger for the user.

  • Page 8: Menu

    The menu is available at any position of the knob. Press MENU. Using buttons highlight the required position. Press ENTER to select the option. Measurement settings Using buttons highlight the required position. Press ENTER to select the option. MRU-120 – USER MANUAL...

  • Page 9: Mains Frequency

    It may be periodically calibrated in order to avoid the influence of the ageing elements upon the resolution of measurements. The procedure of calibration must be realized also after clamp has been replaced. Having read the preliminary infor- mation ENTER. Follow the displayed instructions. MRU-120 – USER MANUAL...
  • Page 10 ERROR: WIRE NOT CONNECTED tions TO H AND E TERMINAL! CALIBRATION ABORTED. PRESS ENTER Incorrect calibra- Check the quality of ERROR: CALIBRATION tion factor the connections COEFFICIENT OUT OF RANGE. and/or replace the CALIBRATION ABORTED. clamp. PRESS ENTER MRU-120 – USER MANUAL...

  • Page 11: Earth Resistivity Settings

    ENTER to confirm. Meter settings Using buttons select required item. Press ENTER to confirm. 2.2.1 LCD contrast Using the buttons set the contrast value and press ENTER. MRU-120 – USER MANUAL...

  • Page 12: Auto-Off Settings

    Visible bar Hidden bar 2.2.4 Date and time Use buttons to select the value to be modified (Day, month, hour, minute). Use buttons to set the value. Once the date and time have been set, press ENTER. MRU-120 – USER MANUAL...

  • Page 13: Battery Discharging

    Before you proceed to updating the programme, download from the manufacturer’s web page (www.sonel.pl) the meter programming software, install it in the computer and connect the meter to the computer. Having chosen the Program update in the MENU, proceed in accordance with the instructions displayed by the programme.

  • Page 14: Measurements

    The meter is ready for measurement. The auxiliary display shows the value of the interference voltage and its fre- quency. The setting bat shows the mains frequency set in the MENU. Press START In order for the test to commence. MRU-120 – USER MANUAL...

  • Page 15: Calibration Of The Test Leads

    (auto-zeroing). In order to do so the measurement function 2P includes the AUTOZERO subfunction. 3.2.1 Auto-zeroing on Turn the meter on. Set the rotational function selector at 2P. Press F1. Follow the displayed instructions. MRU-120 – USER MANUAL...

  • Page 16: Auto-Zeroing Off

    Once the auto-zeroing function has been turned off, the legend AUTOZERO will be no long- er displayed. Note: - It is sufficient to realise compensation once for the given test leads. It is also remembered once the meter has been turned off. MRU-120 – USER MANUAL...

  • Page 17: Earth Resistance Measurement With 3-Pole Method (R 3P)

    The tested earth electrode as well as the current electrode and voltage electrode should be aligned. The meter is ready for measurement. The auxiliary display shows the value of the interference voltage and its fre- quency. The setting bar shows the mains frequency set in the MENU. MRU-120 – USER MANUAL...
  • Page 18 Read out the result. Current electrode resistance Voltage electrode resistance Additional uncertainty caused by the resistance of the electrodes Displayed, when δ>30% The result is displayer for 20 s. It may be displayed again ENTER is pressed. MRU-120 – USER MANUAL...
  • Page 19 The uncertainty of the electrode resistance >30%. (Uncer- LIMIT! tainties calculated on the basis of the measured values) The value of the interfering signal is too high, NOISE! the result may be distorted by additional uncertainty. MRU-120 – USER MANUAL...

  • Page 20: Earth Resistance Measurement With 4-Wire Method (R 4P)

    Connect the tested earth electrode to the E socket of the meter. Connect the ES socket to the earth electrode below the E cable. The tested earth electrode as well as the current electrode and voltage electrode should be aligned. MRU-120 – USER MANUAL...
  • Page 21 Read out the result. Current electrode resistance Voltage electrode resistance Additional uncertainty caused by the resistance of the electrodes The result is displayer for 20 s. It may be displayed again ENTER is pressed. MRU-120 – USER MANUAL...
  • Page 22 The uncertainty of the electrode resistance >30%. (Uncer- LIMIT! tainties calculated on the basis of the measured values) The value of the interfering signal is too high, NOISE! the result may be distorted by additional uncertainty. MRU-120 – USER MANUAL...

  • Page 23: Earth Resistance Measurement With 3-Pole Method With Additional Clamp (R E 3P+C)

    The auxiliary display shows the value of the interference voltage and its frequen- cy. The setting bar shows the mains fre- quency set in the MENU. Press F1 to ordered to modify the meas- uring voltage. MRU-120 – USER MANUAL...
  • Page 24 - If the resistance of the auxiliary electrodes is too high, then the measurement of the R earth elec- trode will be distorted by additional uncertainty. A particularly high measurement uncertainty is gen- MRU-120 – USER MANUAL...
  • Page 25 The uncertainty of the electrode resistance >30%. (Uncer- LIMIT! tainties calculated on the basis of the measured values) Excessive interfering current, the measurement error may >max exceed the basic error MRU-120 – USER MANUAL...

  • Page 26: Earth Resistance Measurement With Two-Clamp Method (2C)

    Snap the transmission clamp and measurement clamp on the tested earth elec- trode AT east 30 cm from each other. The meter is ready for measurement. Press START In order for the test to com- mence measurement. MRU-120 – USER MANUAL...
  • Page 27 The voltage on the measurement points exceeds 24 V >24V! but lower than 40 V, the measurement is blocked. The value of the interfering signal is too high, NOISE! the result may be distorted by additional uncertainty. MRU-120 – USER MANUAL...

  • Page 28: Earth Resistivity Measurement (Ρ)

    The meter is ready for measurement. The auxiliary display shows the value of the interference voltage and its fre- quency. The setting bar shows the measurement voltage, mains frequency set in the MENU and the distance be- tween the electrodes. MRU-120 – USER MANUAL...
  • Page 29 ENTER In order to commerce meas- urement. Read out the result. Current electrode resistance Voltage electrode resistance Additional uncertainty caused by the resistance of the electrodes The result is displayer for 20 s. It may be displayed again ENTER is pressed. MRU-120 – USER MANUAL...
  • Page 30 The uncertainty of the electrode resistance >30%. (Uncer- LIMIT! tainties calculated on the basis of the measured values) The value of the interfering signal is too high, NOISE! the result may be distorted by additional uncertainty. MRU-120 – USER MANUAL...

  • Page 31: Memory

    Memory The MRU-120 meters are equipped with a memory whose capacity is 990 results of resistance measurements. Individual measurements are saved in memory cells. The whole memory is divided into 10 banks with 99 cells each. Each result may be saved in a cell of a defined number and in the...

  • Page 32: Memory Erasing

    Memory erasing Note: - During the process of memory erasing the progress bar is being displayed. Turn the meter on. Set the rotational function selector at MEM. Using the buttons highlight “Memory erasing”. Press ENTER. MRU-120 – USER MANUAL...

  • Page 33: Memory Browsing

    20; cells 21…99 are empty and unavailable. The same principle refers to banks. If the memory is not filled in a continuous manner, then empty measurements and banks are skipped during browsing. MRU-120 – USER MANUAL...

  • Page 34: Data Transmission

    USB cable and appropriate software. If the required accessories such have not been purchased along with the meter, then they are available from the manufacturer or an authorised distributor. The accessories may be used in case of many devices manufactured by SONEL S.A. which are equipped with the USB interface.

  • Page 35: Replacement Of Accumulators

    Replacement of accumulators The MRU-120 meter is equipped with a package of NiMH accumulators and charger. The package of accumulators is placed in a compartment. The charger is installed inside the meter casing and it may be used solely to charge the original accumulators.

  • Page 36: Fuse Replacement

    - As a result of interferences in the network it is possible that the process of charging of accumulators will finish too fast. In the case too short a time of charging is detected it is necessary to remove the plug of the charger and start charging anew. MRU-120 – USER MANUAL...

  • Page 37: Discharging Of Accumulators

    In order to guarantee proper functioning of the accumulators (charge indications) and prolong their durability, it is recommended to charge them from zero from time to time. Proceed as follows in order to discharge the accumulators: Press MENU and highlight Meter settings. Press ENTER. MRU-120 – USER MANUAL...

  • Page 38: General Principles Regarding Using Ni-Mh Accumulators

    - Do not charge or use accumulators in extreme temperatures. Extreme temperatures reduce the life- time of batteries and accumulators. Avoid placing devices powered from accumulators in very hot en- vironments. The nominal working temperature must be absolutely observed. MRU-120 – USER MANUAL...

  • Page 39: Cleaning And Maintenance

    Worn-out electronic equipment should be sent to a collection point in accordance with the law of worn-out electric and electronic equipment. Before the equipment is sent to a collection point, do not dismantle any elements. Observe the local regulations concerning disposal of packages, worn-out batteries and accumula- tors. MRU-120 – USER MANUAL...

  • Page 40: Technical Data

    0,1 kΩ Measurement of resistance of auxiliary electrodes R and R Range Resolution Accuracy 0...999 Ω 1 Ω ±(5% (R 1,00...9,99 kΩ 0,01 kΩ 8 digits) but not less than 10% R 10,0…19,9 kΩ 0,1 kΩ MRU-120 – USER MANUAL...
  • Page 41 ................≤0.5 mA m) power supply of the meter ......accumulator package type SONEL NiMH 4.8 V 3 Ah n) parameters of AC adapter for the battery charge ......100 V…240 V, 50 Hz…60 Hz o) number of measurements for 2P ..........

  • Page 42: Additional Data

    >1 kΩ lub           >1 kΩ lub    >1 kΩ and R [Ω], R [Ω] and R [Ω] are values which are displayed by the device. MRU-120 – USER MANUAL...

  • Page 43: Influence Of The Auxiliary Electrodes Upon Earth Resistance Measurements For Function Ρ

    R 3P+C The MRU-120 meter may perform a measurement, if the value of the interference current does not exceed 3 A RMS and the frequency complies with the value set in the MENU. Uncertainty [] ...

  • Page 44: Additional Uncertainties In Accordance With Iec 61557-4 (2P)

     Harness to carry the device, two pieces (short and long) – WAPOZSZEKPL  USB cable – WAPRZUSB  Accumulator charger (to be used in different countries) – WAZASZ7  Calibration certificate issued by an accredited laboratory  User manual MRU-120 – USER MANUAL...

  • Page 45: Optional Accessories

    Cable to charge the accumulators from the car lighter socket WAFUTL3 WAAKU07  Case (for auxiliary electrodes 80 cm)  Rechargeable battery NiMH 4.8 V 4.2 Ah WAPOJ1  Calibration certificate with accreditation  Batteries compartment MRU-120 – USER MANUAL...

  • Page 46: Positions Of The Meter's Cover

    SONEL S.A. Wokulskiego 11 58-100 Świdnica Poland tel. +48 74 858 38 60 fax +48 74 858 38 09 E-mail: export@sonel.pl Web page: www.sonel.pl Attention: Service repairs must be realised solely by the manufacturer. MRU-120 – USER MANUAL...

  • Page 47: Laboratory Services

    National Metrological Institute. According to ILAC-G24 „Guidelines for determination of calibration intervals of measuring instru- ments”, SONEL S.A. recommends periodical metrological inspection of the instruments it manufac- tures no less frequently than once every 12 months.
  • Page 48 NOTES MRU-120 – USER MANUAL...
  • Page 49 NOTES MRU-120 – USER MANUAL...
  • Page 50 NOTES MRU-120 – USER MANUAL...
  • Page 52 MRU-120 – USER MANUAL...

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