Sonel MRU-21 Operation Manual
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Sonel MRU-21 Operation Manual

Earth resistance meter
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Summary of Contents for Sonel MRU-21

  • Page 3 OPERATING MANUAL Earth Resistance Meter MRU-21 SONEL SA ul. Wokulskiego 11 58-100 Świdnica, Poland Version 1.04 28.04.2017...
  • Page 4 The MRU-21 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 operation of the meter. OPERATING MANUAL MRU-21 version 1.04...

  • Page 5: Table Of Contents

    STORAGE ......................25 DISMANTLING AND UTILIZATION ..............25 TECHNICAL SPECIFICATIONS ............... 26 ......................26 ASIC DATA ................. 28 DDITIONAL INFORMATION 9.2.1 measurement ................... 28 9.2.2 measurement ..................29 CONT EQUIPMENT ......................30 10.1 ..................30 TANDARD EQUIPMENT OPERATING MANUAL MRU-21 version 1.04...
  • Page 6 10.2 ..................30 PTIONAL ACCESSORIES MANUFACTURER ....................31 OPERATING MANUAL MRU-21 version 1.04...

  • Page 7: Safety

     MRU-21 meter is designed to measure earth resistance and the resistance of protective conductors and equipotential bondings. Any application 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: Settings

    = 25V or 50V, SuPP = bAt (disposable batteries) or Acc (rechargeable batteries). Press ENTER to validate the changes and exit the mode, or..press ESC to exit the setting mode without validating the changes. OPERATING MANUAL MRU-21 version 1.04...

  • Page 9: Measurements

    The voltage electrode (driven into earth) should be connected to S socket of the meter. The tested earth electrode should be connected to E socket of the meter. The tested earth electrode and the current electrode and the voltage electrode should be aligned. OPERATING MANUAL MRU-21 version 1.04...
  • Page 10 Resistance of earth electrode R Read the auxiliary results (sequence as below) by pressing << and >>. Resistance of current electrode Resistance of voltage electrode Additional uncertainty caused by resistance of the electrodes. OPERATING MANUAL MRU-21 version 1.04...
  • Page 11 Disconnect the source of interference or try another location of the probes. Interference voltage exceeds 50V! Disconnect the meter immediately! Disconnect the voltage source before you reconnect the and continuous meter.  audio signal OPERATING MANUAL MRU-21 version 1.04...

  • Page 12: Earth Resistance Measurement With The Double-Lead Method

    Earth resistance measurement with the double-lead method Turn on the meter. Turn the rotary switch to the R 2p position. If necessary, adjust the voltage measurement according to section Connect the tested facility to the E and H terminals. 1,2m 2,2m OPERATING MANUAL MRU-21 version 1.04...
  • Page 13  audio signal Interference voltage exceeds 100V! Disconnect the meter immediately! (The symbol is displayed instead of the interference voltage). Disconnect the voltage source before you reconnect the and continuous meter.  audio signal OPERATING MANUAL MRU-21 version 1.04...

  • Page 14: Measurement Of Resistance Of Protective Conductors And Equipotential Bonding

    1.2 m and 2.2 m. Turn on the meter. Turn the rotary switch to the R position. CONT Connect the tested facility to the S and E terminals. 1,2m 2,2m The meter is ready for measurement. OPERATING MANUAL MRU-21 version 1.04...
  • Page 15 1..3Vrms interference voltage during the R measurement. CONT Measurement is slightly unstable. The results may include an additional uncertainty. long audio signal Measurement is highly unstable.  Maximum allowed temperature inside the meter is exceeded. OPERATING MANUAL MRU-21 version 1.04...

  • Page 16: Calibration Of Test Leads

    Press START. Perform autozeroing. Autozeroing completed. Note: - Remember that the resistance of crocodile clips and crocodile-banana connections is added to the resistance of the test leads. OPERATING MANUAL MRU-21 version 1.04...

  • Page 17: Turning Autozero Off

    1.2 m and 2.2 m leads. NOTE It suffices when the compensation for given test leads is performed only once. It is remembered when the meter is turned off. OPERATING MANUAL MRU-21 version 1.04...

  • Page 18: Memory

    Memory The MRU-21 meters feature memory that can store 990 single measurement results The whole memory is divided into 10 memory banks, with 99 cells in each bank. Each measurement result can be stored in a memory cell marked with a selected number and in a selected memory bank. Thanks to this, the user of the meter can, at his/her option, assign memory cell numbers to individual measurement points and the memory bank numbers to individual facilities.
  • Page 19 Press ENTER to overwrite the result or ESC to abort. Note: - Stored in the memory is a complete set of results (main result and supplementary results), as well as the test voltage for R OPERATING MANUAL MRU-21 version 1.04...

  • Page 20: Viewing Memory Data

    Press << or >> to view additional results. Deleting memory data 4.3.1 Deleting bank data Turn on the meter. Turn the rotary switch to the the MEM position. OPERATING MANUAL MRU-21 version 1.04...
  • Page 21 Press ENTER to start deleting or ESC The deletion progress is to abort. shown on the display as dashes (each dash means 25%). When deletion is complete, the meter generates three short beeps and sets the cell number to "1". OPERATING MANUAL MRU-21 version 1.04...

  • Page 22: Deleting The Whole Memory

    Press ENTER . The “?” and symbols appear, asking you to confirm deletion. The deletion Press ENTER to start deleting or progress is shown ESC to abort. on the display as dashes (each dash means 25%). OPERATING MANUAL MRU-21 version 1.04...

  • Page 23: Communication With A Computer

    If the rotary switch is in the MEM position, after detecting the USB connection with a computer the meter automatically goes to the data transmission mode and displays the following screen. To transmit data, follow the instructions of the software. OPERATING MANUAL MRU-21 version 1.04...

  • Page 24: Meter Power Supply

    Consequently, such measurements cannot prove that the tested earthing system is correct. Replacement of batteries The MRU-21 is powered by four R14 disposable or rechargeable batteries (alkaline batteries are recommended). The disposable or rechargeable batteries are placed in the compartment at the bottom of the enclosure.
  • Page 25 Selected power supply: rechargeable batteries: Use the symbols to select the power supply: bAt (disposable batteries) or Acc (rechargeable batteries). Press ENTER to validate the choice The meter goes to the measurement readiness mode. OPERATING MANUAL MRU-21 version 1.04...
  • Page 26 (the discharge characteristics of disposable and rechargeable batteries are different). NOTE! Have the meter serviced in case of battery leakage inside the compartment. Batteries must be recharged in an external charger. OPERATING MANUAL MRU-21 version 1.04...

  • Page 27: Cleaning And Maintenance

    Waste Electrical and Electronic Equipment. Before the equipment is sent to a collection point, do not attempt to dismantle any elements. Observe the local regulations concerning disposal of packages, worn-out batteries and accumulators. OPERATING MANUAL MRU-21 version 1.04...

  • Page 28: Technical Specifications

    =300 1,0000 =100 0,1000 ądowej Rezystancj elektrody  Current electrode resistance  Rezystancj uziemienia Earth resistance 0,0100 =0,3 0,0010 1000 10000 100000 Rezystancja elektrody napięciowej Rs[] Voltage electrode resistance Rs[] Electrodes resistance and measurement uncertainty OPERATING MANUAL MRU-21 version 1.04...
  • Page 29 ........................ 40...60% w) time to AUTO-OFF ......................5 minutes x) the product meets the EMC requirements acc. to PN-EN 61326-1:2006 and PN-EN 61326-2-2:2006 y) quality standard ......development, design and manufacturing are ISO 9001 compliant OPERATING MANUAL MRU-21 version 1.04...

  • Page 30: Additional Information

    , but ≤ Resistance of probes and From 0 to 100R acc. to 50kΩ auxiliary earth electrodes formula from 9.2.1.1          Working uncertainty where A = measurement uncertainty OPERATING MANUAL MRU-21 version 1.04...

  • Page 31: R Measurement

    Designation influencing factors operating range uncertainty Reference position Position ±90° ÷ U Power supply voltage 0 ÷ 35°C ±0.15%/°C Storage temperature        Working uncertainty where A = measurement uncertainty OPERATING MANUAL MRU-21 version 1.04...

  • Page 32: Equipment

    Additionally, the following items that are not included in the scope of standard equipment can be purchased from the manufacturer or the distributors: WAPRZ025BUBBSZ WAZACIMA1  vise  25m test lead (blue) LSWPLMRU21 WAPRZ050YEBBSZ  calibration certificate  50m test lead OPERATING MANUAL MRU-21 version 1.04...
  • Page 33 SONEL S.A. ul. 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 performed solely by the manufacturer. OPERATING MANUAL MRU-21 version 1.04...
  • Page 34 OPERATING MANUAL MRU-21 version 1.04...

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