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, St 58-100 Świdnica Version 1.00 16.01.2018...
  • 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 op- eration of the meter.

  • Page 5: Table Of Contents

    6.2 Fuse replacement ....................34 6.3 Charging of rechargeable batteries ................ 34 6.4 Discharging of rechargeable batteries ..............36 6.5 General principles regarding using Ni-MH rechargeable batteries ......36 7 Cleaning and maintenance ................37 8 Storage ......................37 MRU-120HD – USER MANUAL...
  • Page 6 10.2.8 Additional uncertainties in accordance with IEC 61557-4 (2P) ........41 10.2.9 Additional uncertainties in accordance with IEC 61557-5 (3P, 4P, 3P + clamp) ..... 42 11 Accessories ....................42 11.1 Basic accessories ....................42 11.2 Additional accessories .................... 43 12 Manufacturer ....................44 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 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. 2.1 Wireless transmission See chapter 5.3. 2.2 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 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-120HD – 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-120HD – USER MANUAL...

  • Page 11: Earth Resistivity Settings

    ENTER to confirm. 2.3 Meter settings Using buttons select re- quired item. Press ENTER to confirm. 2.3.1 LCD contrast Using the buttons set the contrast value and press ENTER. MRU-120HD – USER MANUAL...

  • Page 12: Auto-Off Settings

    Visible bar Hidden bar 2.3.4 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

    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. Having chosen the Program update in the MENU, proceed in accordance with the instructions displayed by the program.

  • 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. The setting bar shows the mains frequency set in the MENU. MRU-120HD – 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. MRU-120HD – USER MANUAL...

  • Page 16: Auto-Zeroing Off

    Auto-zeroing is signaled by the legend AUTOZERO on the right-hand side of the display. 3.2.2 Auto-zeroing off Turn the meter on. Set the rotational function selector at 2P. Press F1. Separate the test leads. Press START. MRU-120HD – USER MANUAL...

  • Page 17: Measurement

    Connect the voltage electrode driven into ground to the S socket of the meter. Connect the tested earth electrode to the E socket of the meter. The tested earth electrode as well as the current electrode and voltage electrode should be aligned. MRU-120HD – 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 displayed for 20 s. It may be displayed again when ENTER is pressed. MRU-120HD – USER MANUAL...
  • Page 19 The uncertainty of the electrode resistance > 30%. (Un- LIMIT! certainties calculated on the basis of the measured val- ues) The value of the interfering signal is too high, NOISE! the result may be distorted by additional uncertainty. MRU-120HD – USER MANUAL...

  • Page 20: Measurement

    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 21 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 22 The uncertainty of the electrode resistance > 30%. (Un- LIMIT! certainties calculated on the basis of the measured val- ues) The value of the interfering signal is too high, NOISE! the result may be distorted by additional uncertainty. MRU-120HD – USER MANUAL...

  • Page 23: Measurement + Clamp

    The auxiliary display shows the value of the interference voltage and the value of the leakage current passing through the clamp. 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 24 The clamp calibration option is in the MENU. - Pay particular attention to the quality of the connection of the tested object with the test leads – the contact area must be cleaned of paint, rust, etc. MRU-120HD – USER MANUAL...

  • Page 25: Two-Clamp Measurement

    3.6 Two-clamp measurement Two-clamp measurements are applied where there is no possibility of using ground-driven elec- trodes. NOTE! The two-clamp method may be used solely in the case of multiple earthing measurements. MRU-120HD – USER MANUAL...
  • Page 26 Press START in order for the test to com- mence measurement. Read out the result. The result is displayed for 20 s. It may be displayed again when ENTER is pressed. MRU-120HD – USER MANUAL...

  • Page 27: Earth Resistivity Measurements

    π ρ = 2 which is used in the Wenner’s measurement method. The method in question assumes equal dis- tances between electrodes. Turn the meter on. Set the rotational function selector at ρ. MRU-120HD – USER MANUAL...
  • Page 28 The setting bar shows the measurement voltage, mains frequency set in the MENU and the distance between the electrodes. Press F1 to change the measurement voltage. Use buttons to set the measur- ing voltage and press ENTER. MRU-120HD – USER MANUAL...
  • Page 29 - Calculations are based upon the assumption that the distances between the specific measurement electrodes are equal (the Wenner’s method). If this is not the case the earthing resistance measure- ment must be realized by means of the four-pole method and calculations must be performed individ- ually. MRU-120HD – USER MANUAL...
  • Page 30 The uncertainty of the electrode resistance > 30%. (Un- LIMIT! certainties calculated on the basis of the measured val- ues) The value of the interfering signal is too high, NOISE! the result may be distorted by additional uncertainty. MRU-120HD – USER MANUAL...

  • Page 31: 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 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

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

  • Page 34: Data Transmission

    The accessories may be used in case of many devices manufactured by SONEL S.A. which are equipped with the USB interface. In addition, it is possible to purchase the OR-1 radio module for wireless data transmission.

  • Page 35: Data Transmission With Or-1 Radio Module

    Active wireless connection. If it is impossible to establish connection the message Wire- less connection lost will appear. Once the connection is established, follow the program manual for data filing. Standard PIN code for OR-1 is „123”. MRU-120HD – USER MANUAL...

  • Page 36: Power Supply

    Charging commences once the power supply has been connected to the meter regardless of the fact whether the meter is on or off. During charging the screen looks as it is presented in the following illustration. MRU-120HD – USER MANUAL...
  • Page 37 The message is displayed for a charged rechargeable bat- while and then the precharge pro- teries package cess begins again. If after several attempts the mes- Precharge error sage: Battery temperature too high! is displayed, contact the manufacturer MRU-120HD – USER MANUAL...

  • Page 38: Discharging Of Rechargeable Batteries

    - During storage of Ni-MH rechargeable batteries they are discharged at the rate of approximately 30% per month. Keeping them at high temperatures may accelerate this process even 100%. In or- der to prevent excessive discharge of rechargeable batteries, after which it would be necessary to MRU-120HD – 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 rechargeable batteries. MRU-120HD – USER MANUAL...

  • Page 40: Technical Data

    ±(8% m.v. + 3 digits) 200..1999 Ω 1 Ω Measurement of multiple earth resistance with double clamp Range Resolution Basic uncertainty 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 41 Signaling of insufficient clamp current for ................≤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 R 2P ........

  • Page 42: Additional Data

    3P+clamp 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.

  • Page 43: Influence Of Interference Current Upon The Result Of The Earth Resistance Measurement Using Two Clamps

    10.2.6 Influence of interference current upon the result of the earth resistance measurement using two clamps 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.

  • Page 44: Additional Uncertainties In Accordance With Iec 61557-5 (3P, 4P, 3P + Clamp)

    • Black crocodile clip • Green crocodile clip • Harness to carry the device • USB 2.0 cable • Meter protective cover • Device charger • Black power cord • User manual MRU-120HD – USER MANUAL...

  • Page 45: Additional Accessories

    80 cm measurement probe to be driven Transmission clamp N-1 into the ground WAZACIMA1 WACEGC3OKR • • Cramp Receiving clamp C-3 WAPRZLAD12SAM WAFUTL3 • Cable to charge the rechargeable batter- • 80-cm probe protective cover ies from the car lighter socket MRU-120HD – USER MANUAL...

  • Page 46: Manufacturer

    SONEL S.A. Wokulskiego 11, St 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...

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