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

Earth resistance meter
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Summary of Contents for Sonel MRU-120HD

  • Page 3 USER MANUAL EARTH RESISTANCE METER MRU-120HD SONEL S.A. Wokulskiego 11 58-100 Świdnica Version 1.04 28.07.2021...
  • Page 4 The MRU-120HD 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 oper- ation of the meter. MRU-120HD – USER MANUAL...

  • Page 5: Table Of Contents

    6.4 Discharging of rechargeable batteries ..............36 6.5 General principles regarding using Ni-MH rechargeable batteries ......37 7 Cleaning and maintenance ................38 8 Storage ......................38 9 Dismantling and disposal ................38 10 Technical data ....................39 MRU-120HD – USER MANUAL...
  • Page 6 3P+C) ... 43 11 Accessories ....................43 11.1 Standard accessories (non-Australian model version) ........... 43 11.2 Standard accessories (Australian model version) ..........43 11.3 Optional accessories ....................44 12 Manufacturer ....................46 13 Laboratory services ..................47 MRU-120HD – USER MANUAL...

  • Page 7: Safety

     The MRU-120HD meter has been designed for the purpose of measurements of earth connection and equipotential bonding, ground resistivity, as well as clamps current measurements. Any appli- cation that differs from those specified in the present manual may result in a damage to the device 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. 2.1 Measurement settings Using buttons highlight the required position. Press ENTER to select the option. MRU-120HD – USER MANUAL...

  • Page 9: Mains Frequency

    It may be periodically calibrated in order to avoid the influence of the ageing el- ements 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-120HD – USER MANUAL...
  • Page 10 TO H AND E TERMINAL! Revise the connec- No wire CALIBRATION ABORTED. tions PRESS ENTER ERROR: CALIBRATION Check the quality of COEFFICIENT OUT OF RANGE. Incorrect calibra- the connections CALIBRATION ABORTED. tion factor and/or replace the PRESS ENTER clamp. MRU-120HD – USER MANUAL...

  • Page 11: Earth Resistivity Settings

    2.1.3 Earth resistivity settings ▲▼◄► Using buttons select the result and the distance unit and press ENTER to confirm. 2.2 Meter settings Using buttons select re- quired item. Press ENTER to confirm. MRU-120HD – USER MANUAL...

  • Page 12: Lcd Contrast

    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-120HD – USER MANUAL...

  • Page 13: Battery Discharging

    During programming do not turn the meter off or disconnect the transmission cable. Before you proceed to updating the program 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.

  • Page 14: Measurements

    Connect the object being measured to the terminals S and E of the meter. The meter is ready for measurement. The auxiliary display shows the value of the interference voltage and fre- quency. The setting bar shows the mains frequency set in the MENU. MRU-120HD – USER MANUAL...
  • Page 15 The voltage on the measurement points exceeds 24 V >24V! but it is 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-120HD – USER MANUAL...

  • Page 16: Calibration Of The Test Leads

    2P. Press F1. Follow the displayed instructions. Once the auto-reset function has concluded the following will be displayed: Auto-zeroing is signaled by the legend AUTOZERO on the right-hand side of the dis- play. MRU-120HD – USER MANUAL...

  • Page 17: Auto-Zeroing Off

    Once the auto-zeroing function has been turned off, the legend AUTOZERO will be no longer displayed. It is sufficient to realize compensation once for the given test leads. It is also remem- bered once the meter has been turned off. MRU-120HD – USER MANUAL...

  • Page 18: 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 fre- quency. The setting bar shows the mains frequency set in the MENU. MRU-120HD – USER MANUAL...
  • Page 19 If the R test results differ more than 3%, then it is necessary to increase significantly the distance between the current electrode from the earth electrode in question and repeat the measurement. MRU-120HD – USER MANUAL...
  • Page 20 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-120HD – USER MANUAL...

  • Page 21: 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-120HD – USER MANUAL...
  • Page 22 Read out the result. Current electrode resistance Voltage electrode resistance Additional uncertainty caused by the resistance of the electrodes The result is displayed for 20 s. It may be displayed again when ENTER is pressed. MRU-120HD – USER MANUAL...
  • Page 23 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-120HD – USER MANUAL...

  • Page 24: Earth Resistance Measurement With 3-Pole Method With Additional Clamp (R E 3P+C)

    The meter is ready for measurement. The auxiliary display shows the value of the interference voltage. The setting bar shows the mains frequency set in the MENU. Press F1 to ordered to modify the meas- uring voltage. MRU-120HD – USER MANUAL...
  • Page 25  Earth resistance measurement may be realized if the interference voltage does not exceed 24 V. The interference voltage is measured up to 100 V. Do not connect the meter to a voltage exceeding 100 V. MRU-120HD – USER MANUAL...
  • Page 26 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-120HD – USER MANUAL...

  • Page 27: Earth Resistance Measurement With Two-Clamp Method (2C)

    30 cm from each other in order to avoid the influence of transmitting clamp on the receiving clamp. The meter is ready for measurement. Press START in order for the test to com- mence measurement. MRU-120HD – USER MANUAL...
  • Page 28 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, the result NOISE! may be distorted by additional uncertainty. MRU-120HD – USER MANUAL...

  • Page 29: Earth Resistivity Measurement (Ρ)

    The auxiliary display shows the value of the interference voltage and frequency. The setting bar shows the measure- ment voltage, mains frequency set in the MENU and the distance between the electrodes. Press F1 to change the measurement voltage. MRU-120HD – USER MANUAL...
  • Page 30 In order to commence measurement. Read out the result. Current electrode resistance Voltage electrode resistance Additional uncertainty caused by the resistance of the electrodes The result is displayed for 20 s. It may be displayed again when ENTER is pressed. MRU-120HD – USER MANUAL...
  • Page 31 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-120HD – USER MANUAL...

  • Page 32: Memory

    Memory The MRU-120HD 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 in- to 10 banks with 99 cells each. Each result may be saved in a cell of a defined number and in the se-...

  • Page 33: Memory Erasing

    4.2 Memory erasing 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-120HD – USER MANUAL...

  • Page 34: 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-120HD – USER MANUAL...

  • Page 35: Data Transmission

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

  • Page 36: Power Supply

    If the instrument or battery charger does not work, before sending it for servicing, check the fuses and, if they are blown, replace them with identical ones. The fuses are placed in holders. To remove the fuses, use a narrow tool (e.g. a screwdriver). MRU-120HD – USER MANUAL...

  • Page 37: Charging Of Rechargeable Batteries

    The message is displayed for a while and then the pre- charged rechargeable bat- charge process begins again. Precharge error If after several attempts the message: Battery tempera- teries package ture too high! is displayed, contact the manufacturer MRU-120HD – USER MANUAL...

  • Page 38: Discharging Of Rechargeable Batteries

    ENTER. Read the displayed text and accept. Discharging, which may last up to 10 hours depending on the level of the charge of the package, is signaled with the following message: Discharge in progress. MRU-120HD – USER MANUAL...

  • Page 39: General Principles Regarding Using Ni-Mh Rechargeable Batteries

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

  • Page 40: 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 rechargeable batteries. MRU-120HD – USER MANUAL...

  • Page 41: Technical Data

    ±(8% m.v. + 3 digits) 200..1999 Ω 1 Ω Measurement of multiple earth resistance – two-clamp method (2C) Range Resolution Accuracy 0.00...19.99 Ω 0.01 Ω ±(10% m.v. + 3 digits) 20.0...149.9 Ω 0.1 Ω ±(20% m.v. + 3 digits) MRU-120HD – USER MANUAL...
  • Page 42 ................≤0.5 mA m) power supply of the meter....rechargeable batteries 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 43: Additional Data

    10.2.4 Influence of the auxiliary electrodes upon earth resistance measurements for function ρ Uncertainty [%]      30000          [Ω], R [Ω], R [Ω] – values which are displayed by the device. MRU-120HD – USER MANUAL...

  • Page 44: Influence Of Interference Current Upon The Result Of The Earth Resistance Measurement Using Two Clamps

    R 3P+C The MRU-120HD 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 [Ω] ...

  • Page 45: Additional Uncertainties In Accordance With Iec 61557-5 (R 3P, R 4P, R 3P+C)

     Black crocodile clip 1 kV 20 A – WAKROBL20K01  Green crocodile clip 1 kV 20 A – WAKROGR20K01  USB cable – WAPRZUSB  Mains power cable Euro 2-pin plug / IEC C7 plug – WAPRZLAD230AU  Z7 power supply adapter – WAZASZ7 MRU-120HD – USER MANUAL...

  • Page 46: Optional Accessories

     Adapter ERP-1 with flexible clamps FSX-3 and case – WAADAERP1V3 WACEGFS2OKR WACEGFSX3OKR   FS-2 flexible coil (Φ=1260 mm), output level FSX-3 flexible coil (Φ=630 mm), output level 100 mV / 1 A 300 mV / 1 A MRU-120HD – USER MANUAL...
  • Page 47  Auxiliary electrode, 80 cm Case L-3 (for auxiliary electrodes 80 cm) WACEGN1BB WACEGC3OKR   Transmission clamp N-1 Receiving clamp C-3 WAPRZLAD12SAM  Cable to charge the rechargeable bat- teries from the car lighter socket MRU-120HD – USER MANUAL...

  • Page 48: Manufacturer

    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 NOTE! Service repairs must be realized solely by the manufacturer. MRU-120HD – USER MANUAL...

  • Page 49: 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 50 NOTES MRU-120HD – USER MANUAL...

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