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1. 26 9 2 ADDITIONAL INFORMATION ii ceca cosucces 28 9 2 1 cesta E 26 9 2 2 REONEMEGSUKENIE I a nettes eei Area tte aai est 29 I0 EQUIPMENT zasada fies 30 IOI STANBARDEOUIEME NT ubuntu 30 OPERATING MANUAL MRU 21 version 1 03 3 10 2 OPTIONAL ACCESSORIBS beta eam Cadet enter es enin uses 11 MANUFACTURER m OPERATING MANUAL MRU 21 version 1 03 1 Safety MRU 21 meter is designed for measuring parameters important for safety of electrical installations Therefore in order to provide conditions for correct operation and the correctness of the obtained results the following recommendations must be observed Before you proceed to operate the meter acquaint yourself thoroughly with this manual and observe the safety regulations and specifications defined by the producer 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 The meter must be operated solely by appropriately qualified personnel members holding required certificates for carrying measurements in electric installations Unauthorized use of the meter may
2. Interference voltage causing Un __ Bank and cell number additional measurement V Ee M Display value symbol R resistance RIS AUTO ZERO R earth resistance i1 R H electrode resistance qb D kQ 9 0 S electrode resistance Q LI additional uncertainty caused Li by electrodes resistance ma a AA Unit and type of displayed value uncertainty Main result reading ER field o gt Q e Test leads resistance compensated ohms kiloohms resistance percent additional uncertainty V volts interference voltage S gt ner OPERATING MANUAL Earth Resistance Meter MRU 21 SONEL SA ul Wokulskiego 11 58 100 Swidnica Poland Version 1 03 01 07 2014 The MRU 21 meter is 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 2 OPERATING MANUAL MRU 21 version 1 03 5 1 SAFETY a EA ES 5 2 R 6 3 MEASUREMENTS AGE eese 7 3 1 EARTH RESISTANCE MEASUREMENT WITH THE THREE LEAD 7 3 2 EARTH RESISTANCE MEASUREMENT WITH THE DOUBLE LEAD METHOD 10 3 3 MEASUREMENT OF RESISTANCE OF PROTE
3. AE R G aa iGO 125 Hz PRE LOCI ae Odo hae Ce Te 25V or 50V uide de P 20mA maximum resistance of test electrodes 50kQ Hcowr test current with shorted terminals for Ugat 2 6 0 200 maximum voltage at open terminals for 13V meter power supply R14 alkaline disposable or rechargeable batteries 4 pcs number of measurements gt 1000 50 2 measurements per minute dimension Mc T PEN 288 x 223 x 75 mm WEIGHT with Datlefles A d van xx ubt ra Rec era O Fusco ua about 1 4 kg tenete e dtum oid et EE S uU Eta otn LCD with backlight Operalirig Ter nia eec ces eoa ve m et eed as 10 55 C reference temperature oie dedico l GEO E Ezd dE 23 2 C Storage temper erae Ea da kr clear AW 20 70 RUMIA 20 80 rererenoe MUMIA aa ficte ao atacan 40 60 IIMETOAUTOFOR EE 5 minutes the product m
4. To replace the batteries e remove all test leads from the sockets and turn the meter off e remove the four screws of the battery compartment in the lower part of the enclosure e remove the compartment and take off the lid use a tool e remove and replace all batteries observing the correct polarity when putting new batteries on the spring Reverse polarity will not damage the meter or the batteries but the meter will not work put on the lid place the compartment and secure it with 4 screws 22 OPERATING MANUAL MRU 21 version 1 02 ENTER After replacement of batteries the meter when turned on starts in the power supply selection mode Selected power supply rechargeable batteries 1 Use the A and W symbols to select the power supply bAt disposable batteries or Acc G rechargeable batteries Press ENTER to validate the choice The meter goes to the measurement readiness mode OPERATING MANUAL MRU 21 version 1 02 23 After replacing the batteries always set the power supply type The correct charge indication depends on this setting 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 24 OPERATING MANUAL MRU 21 version 1 02 6 Cleaning and maintenance NOTE Apply only maintenance methods specified by t
5. OPERATION MANUAL EARTH RESISTANCE METER MRU 21 MRU 21 S measurement socket to connect the measured resistance E R measurement socket to connect P PE Rconr measurement socket for continuity measurement the measured resistance Rconr measurement socket for continuity measurement H measurement socket to connect the current electrode Exit the settings or a function Meter ON OFF Start the measurement After energizing procedure the display shows all the symbols and digits display test Enter the meter settings Display backlight ON OFF Enter in the memory validate the settings UP DOWN change the parameter ROTARY SWITCH change the memory cell Choice of the measurement function LEFT RIGHT go to View the measurement 2p double lead earth resistance measurement previous next parameter memory components 3p three lead earth resistance measurement change the memory bank Rea continuity measurement of protective conductors and equipotential bonding ZERO compensation of test leads resistance for continuity measurement of protective conductors and equipotential bonding MEM view and delete the memory DISPLAY Additional Parameters configuration mode reading field Battery charge status Memory mode active Important error information SET MEM TTL use the operating manual
6. Press ENTER again The screen shown below appears for a moment accompanied by three short beeps and then the meter returns to display the last result of the measurement Bank Cell w w 1 L a 4 An attempt to overwrite a result causes the warning symbol to appear Bank Cell 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 Re OPERATING MANUAL MRU 21 version 1 03 17 4 2 Viewing memory data oO y Bank Cell Turn on the meter Turn the rotary switch to the MEM position CED The content of the last saved cell appears Un E ICO o ALILI 4 Qe Use the gt symbols to select the bank or use the A and v symbols to select the cell Press or to view additional results u lt lt gt gt 43 Deleting memory data 4 3 1 Deleting bank data Ron dia 2P MEM OPERATING MANUAL MRU 21 version 1 03 Turn on the meter Turn the rotary switch to the the MEM position 18 2 CED d LI Bank Cell AL LLL Press ENTER Bank Cell JE LLL to abort Set the bank number to be deleted Set the cell number before 1 the cell number disappears and appears the symbol EL indicating the readiness to delete
7. The and 4 symbols appear asking you to confirm deletion Press ENTER to start deleting or ESC deletion progress is shown on the Bank Cell 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 02 19 4 3 2 Deleting the whole memory 20 Turn on the meter Turn the rotary switch to the MEM position Recon PE 2P MEM CI d 2 Set the bank number between 0 and Bank Cell i C the bank number disappears and appears the symbol L indicating the readiness to delete Bank Cell Press ENTER dil The and A symbols appear Bank Cell asking you to confirm deletion Press ENTER to start deleting or deletion ESC to abort progress is shown on the display as dashes each dash means 25 OPERATING MANUAL MRU 21 version 1 02 CED When deletion is complete the meter generates three short beeps and sets the bank number to and the cell number to 1 44 Communication with a computer 4 4 1 Computer connection accessories What is necessary in order to operate the meter with a computer is additional accessories namely a cable for serial transmission and appropriate software If this package has not been pur
8. WASONG30 carrying case for the meter and accessories harness 2 pcs long and short WAPOZSZEKPL USB cable WAPRZUSB LR14 batteries 4 pcs SONEL CD operating manual warranty card calibration certificate 10 2 Optional accessories 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 e vise 25m test lead blue LSWPLMRU21 WAPRZO50YEBBSZ 30 50m test lead OPERATING MANUAL MRU 21 version 1 02 WASONG80 e 80cm test probe WAFUTL3 e calibration certificate e cover for the 80cm test probe 11 Manufacturer The manufacturer of the device and provider of warranty and post warranty service SONEL S A ul Wokulskiego 11 58 100 Swidnica Poland tel 48 74 858 38 60 fax 48 74 858 38 09 E mail export 2sonel pl Web page www sonel pl NOTE Service repairs must be performed solely by the manufacturer OPERATING MANUAL MRU 21 version 1 02 31 32 Multifunction Electrical Installations Meter Resistance and MRU 200 ow Earth Resistance MIC 2 Insulation Tana Resistance imager PQM 701 Power quality analyzer Datalogging Light T CMP 1006 CMM 40 ay Industrial Digital Clamp on multimeter AY Tr multimeter DIT 500 IR thermometer MPI 502 Multifunction Electrical Installations MIC
9. OPERATING MANUAL MRU 21 version 1 03 13 3 4 Calibration of test leads In order to eliminate the impact of the resistance of test leads on the measurement result the compensation autozeroing of resistance may be performed This is made with the AUTOZERO function in the Rcont measurement 3 4 1 Turning AUTOZERO on W j j Turn on the meter Turn the rotary switch to the the Rconr ZERO position N 3 o 3 fa lt Short the test leads by putting crocodile clips on exposed ends of the 2 m C test leads 3 5 Perform autozeroing R Autozeroing T d i Q completed Note Remember that the resistance of crocodile clips and crocodile banana connections is added to the resistance of the test leads 14 OPERATING MANUAL MRU 21 version 1 03 3 4 2 Turning AUTOZERO off W 2 a 8 m W CATIV300V m e 8 j af B lt Press START NOTE Turn on the meter Turn the rotary switch to the the Rconr ZERO position Disconnect the test leads Autozeroing is off During the measurements the meter will compensate the resistance of the supplied 1 2 m and 2 2 m leads 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 03 15 4 Memory The MRU 21 meters
10. The device meets the requirements of standards EN 61010 1 and EN 61557 1 4 5 Attention The manufacturer reserves the right to introduce changes in appearance equipment and technical data of the meter Note An attempt to install drivers in 64 bit Windows 8 may result in displaying Installation failed message Cause Windows 8 by default blocks drivers without a digital signature Solution Disable the driver signature enforcement in Windows OPERATING MANUAL MRU 21 version 1 03 5 2 Settings Press the SET button to select the test voltage Un or power supply source SuPP After replacing the batteries always set the power supply type The correct charge indication depends on this setting the discharge characteristics of disposable and rechargeable batteries are different W Turn the meter press SET SET Use the 4 and gt buttons to select the parameter Un or Use the A and v buttons to change the parameters Un 7 25V or 50V SuPP bAt disposable batteries Acc rechargeable batteries SET REKE SET EIE bAt un burr 4 Press ENTER to validate the changes and exit the mode or ENTER press ESC to exit the setting mode without validating the changes 6 OPERATING MANUAL MRU 21 version 1 03 3 Measurements 3 1 Earth resistance measurement with the three lead method The three lead measuring method is the basic t
11. or you can use the graph also included in the appendix This uncertainty is also displayed in as an additional result It is calculated on the basis of measured valued If such additional uncertainty exceeds 3096 the Err symbol is displayed You can improve the contact between the probe and soil for example by dampening with water the place where the probe is driven into earth driving the probe into earth in a different place or using a 80 cm long probe Check also the test leads for possible insulation damage and for corroded or loosened connection between the banana plug and the test lead In majority of cases the measurement accuracy achieved is satisfactory However one should always be aware of the uncertainty included in the measurement Factory calibration includes the resistance of the 2 2 m test lead supplied Additional information displayed by the meter Excessive interference voltage 24V The measurement is not possible Disconnect the source of interference or try another location of the probes 2 GL and Interference voltage exceeds 50V A Disconnect the meter immediately Disconnect the voltage source before you reconnect the audio signal o OPERATING MANUAL MRU 21 version 1 03 9 L gt ofl d Interference voltage exceeds 100V an Disconnect the meter immediately A Disconnect the voltage source before you reconnect the and continuous meter audio signal o with the electr
12. this setting the discharge characteristics of disposable and rechargeable batteries are different Replace or recharge the batteries Error detected during the self check The MRU 20 instruments are often exposed to strong electromagnetic disturbance which can affect the internal registers The meter automatically controls some parameters and displays the error messages if necessary Displaying an error message may be caused by a momentary influence of external factors Switch off and again switch on the instrument If the problem persists send the meter for servicing Or and A Maximum allowed temperature inside the meter is exceeded Err and error No on the main reading field SONEL S A Wokulskiego 11 St 58 100 Swidnica Poland Ty 48 74 85 83 860 48 74 85 83 800 fax 48 74 85 83 808 http www sonel pl e mail export sonel pl
13. 30 Insulation Resistance MMR 630 Microohmeters OPERATING MANUAL MRU 21 version 1 02 MIC 2510 Insulation Resistance Meter PAT 805 Portable appliance tester LKZ 700 Wire tracer WARNINGS AND INFORMATIONS DISPLAYED BY THE METER ATTENTION The meter is designed for measurements at interference voltages which do not exceed 24V for the RE measurements and 3V for the RCONT measurements The voltage is measured up to 100V but above 50V is indicated as dangerous The meter must not be connected to voltages exceeding 100 V Excessive interference voltage gt 24V The measurement is not possible Disconnect the source of interference or try another location of the probes Interference voltage during the R measurement exceeds 50V gt A and Disconnect the meter immediately continuous audio signal Disconnect the voltage source before you reconnect the meter DFL A Interference voltage during the R measurement exceeds 100V gt EIL and and Disconnect the meter immediately continuous audio signal Disconnect the voltage source before you reconnect the meter Excessive interference voltage during the RCONT measurement gt 3Vrms gt 1 A The measurement is not possible Disconnect the source of interference Interference voltage during the R measurement exceeds 50V A and Disconnect the meter immediately continuous audio signal Disconnect the voltage sour
14. CTIVE CONDUCTORS AND EQUIPOTENTIAL BONDING csecseccsccsccsccsscescescescescesccsscscescescessescesccuscescessesees 12 3 4 CALIBRATION OF TESTDEEADS nad eat Saran ices wad indes ZA Eu ond 14 3 4 1 Turning XU TOZHRO ON wad ate qaasi ae tme Eia GA 14 3 4 2 Tune BAO TOZERO OJ exitoso tt t EEEE OE 15 4 cocoa E A EIL CD D D ACIE LEID a 16 4 1 STORING THE MEASUREMENT RESULT DATA IN THE MEMORY 16 4 2 MIEWING MEMORY DAT Aisi E E eee pio aad tud eu tad UP 18 4 3 DELETING MEMORY DA PA wa ani ed oun 18 4 3 1 Delene Dank ditas ie 18 43 2 De leting the whole MEMOM Ep E 20 4 4 COMMUNICATION WITH A COMPUTER sccscecesceccececscscccscecesceccscesescucescesescecs 21 4 4 1 Computer CONNECTION accessories 21 4 4 2 SU OV S dk 24d 5 METER POWER SUPPE X 1 eerie edes T sk 22 5 1 MONITORING OF THE POWER SUPPLY VOLTAGE cccccecceceecececcscescscesescesescesescs 22 5 2 REPLACEMENT BATTERIES EG oe CENE E Deae Ope EA oso Sae ine 22 6 CLEANING AND MAINTENANCE 22220000000000000000000000000000000000000000000000000000000 25 7 STORAGE dA WO ad AOL Ga aE EAE Niara 25 8 DISMANTLING AND UTILIZATION 2222020000000000000000000000000000000000000000000 25 9 TECHNICAE SPECIFICATIONS aaa pas uo 26 9 1 DASIE DATA
15. ce before you reconnect the meter f with the electrode Interruption in measuring circuit or resistance of test probes higher than 60 kQ electrodes name and Check connections in the test circuit or reduce the probe resistance by driving it into the soil again Er in the field below Cell Uncertainty of the RE measurement caused by probes resistance exceeds 30 and measurement Reduce the probe resistance by driving it into the soil again or by dampening resul the soil in its immediate vicinity anc 21 99kQ The Rz measuring range is exceeded 1990 The Reon measuring range is exceeded gt 50kQ Test probes resistance above 50kQ but below 60kQ The interference voltage for RE exceeds 100V the symbol is displayed instead of the result Interference voltage equal to 1 3Vrms during the Reor measurement The measurement results may include an additional uncertainty Interference voltage above 10V during the RE measurement or unstable measurement result or the measured voltages or currents are too low in relation to the noise Measured voltages or currents are too low in relation to the noise The symbol nm 5 is displayed instead of the result The default leads resistance has been restored in the function The user s autozeroing of the leads is OFF Status of batteries Batteries charged Batteries discharged After replacing the batteries set the power supply type The correct charge indication depends on
16. chased along with the meter it can be bought from the manufacturer or an authorized distributor where detailed software information is also available 4 4 2 Data transmission 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 02 21 5 Meter power supply 5 1 Monitoring of the power supply voltage The charge level of the batteries or rechargeable batteries is indicated by the symbol in the right upper corner of the display on a current basis Batteries charged d 1 Batteries discharged bH Replace recharge the batteries Note The bHE symbol on the display means insufficient power supply voltage and the need to replace or recharge the batteries e Measurements performed with an insufficient supply voltage feature additional errors which the user is unable to evaluate Consequently such measurements cannot prove that the tested earthing system is correct 5 2 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 WARNING Before replacing the batteries disconnect the test leads from the meter
17. ectrodes resistance and measurement uncertainty OPERATING MANUAL MRU 21 version 1 02 Measurement of resistance of auxiliary earth electrodes Ru Rs Measurement uncertaint 000 9990 1 00 9 99kQ 0 01kQ 5 Rs Re Ru 3 digits 10 0 50 0kQ Measurement of interference voltages Internal resistance about 100kQ Display range Measurement uncertainty 0 100V 2 m v 3 digits measurement Measurement method technical Measuring range according to IEC 61557 4 Q Measurement uncertaint 0 00 9 9902 0 010 10 0 99 90 2 m v 3 digits 100 1990 Note Guaranteed are only the values with tolerances limits Values without tolerances are for information only Other technical specification 3555S Tel cot type of insulation ss GG GC double PN EN 61010 1 61557 compliant measurement Weer es vent IV 300V acc to PN EN 61010 1 degree of protection of enclosure to PN EN 60529 IP54 maximum interference voltage for the RE 24V maximum interference voltage for the Rconr 3V maximum measured interference voltage ee ea aaa aaa ae aaa aaa aaa 100V BE Test carent zas AOR
18. eets the EMC requirements acc to PN EN 61326 1 2006 and PN EN 61326 2 2 2006 quality standard development design and manufacturing are ISO 9001 compliant OPERATING MANUAL MRU 21 version 1 02 27 9 2 Additional information Data on additional uncertainties are useful mainly when the meter is used in non standard conditions and for metrological laboratories for the purpose of calibration 9 2 1 Re measurement 9 2 1 1 Additional uncertainty caused by resistance of auxiliary earth electrodes and Rs lt 1000 Ry 2 5kQ or Rs 2 7 5 gt 5000 Rs gt 5kO and lt E 5000 R R 0 004 1504 amp ini dod R R E o6 remaining cases The meter displays Ru and Rs in O This uncertainty is calculated by the meter and displayed as ER R 0 004 s 1 5 10 s oc 9 2 1 2 Additional uncertainty caused by serial interference voltage Additional uncertainty Q 0 01Re 0 012 U 0 007U 2 0 00 9 99Q 0 01Re 0 012 U 0 003U 2 10 0 99 902 25V 50V 0 001RE 0 05 U 0 001U 100Q 1 99kO 0 001Rz 0 5 U 0 001 9 2 1 3 Additional uncertainty caused by ambient temperature 0 25 digit C for Uwy 50V 0 33 digit C for Uwy 25V 9 2 1 4 Additional uncertainties according to IEC 61557 5 Working uncertainty or Reference conditions or Additional Designation influencing factors operating ran
19. 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 The user can also perform measurements in any sequence and repeat them without losing other data Memory of measurement result data is not deleted when the meter is switched off Thanks to this the data can be later read or sent to a computer The number of a current memory cell or memory bank is not changed either Note One cell can contain the results of a single measurement After each entry of the measurement result to the cell its number is automatically incremented It is recommended to delete the memory after reading the data or before performing a new series of measurements that may be stored into the same memory cells as the previous ones 41 Storing the measurement result data in the memory W Press ENTER after completion of the measurement The meter is in the memory storing mode ENTER Bank Cell e o o o Cell is empty Use the lt and gt symbols to select the a gt bank or use the and v symbols to select the cell 16 OPERATING MANUAL MRU 21 version 1 03
20. ge uncertainty cz Reference position EC cr Power supply voltage Storage temperature 35 C E3 from 9 2 1 3 acc to formula from 9 2 1 2 Serial interference voltage 3 Resistance of probes and From 0 to 100Re but lt acc to auxiliary earth electrodes 50kQ E5 formula from 9 2 1 1 B SAIS AE E E E E where A measurement uncertainty Working uncertainty 28 OPERATING MANUAL MRU 21 version 1 02 9 2 2 Rconr measurement 9 2 2 1 Additional uncertainty caused by ambient temperature 0 15 C 9 2 2 2 Additional uncertainties according to IEC 61557 4 Working uncertainty or Reference conditions or Designation Additional influencing factors operating range uncertaint Reference position pep Power supply voltage Storage temperature 0 35 C m Working uncertainty 1 154 E where measurement uncertainty OPERATING MANUAL MRU 21 version 1 02 29 10 Equipment 10 1 Standard equipment Standard set of equipment supplied by the manufacturer includes MRU 21 meter WMPLMRU21 set of test leads 30m lead on the reel red with banana plugs WAPRZOSOREBBSZ 15m lead on the reel blue with banana plugs WAPRZ015BUBBSZ 2 2m lead black with banana plugs WAPRZ2X2BLBB 1 2m lead blue with banana plugs WAPRZ1X2BUBB K01 crocodile clip black WAKROBL20K01 K02 crocodile clip blue WAKROBU20K02 30cm test probe 2 pcs
21. he manufacturerin this manual The casing of the meter and its case may be cleaned with a soft damp cloth using all purpose detergents Do not use any solvents or cleaning agents which might scratch the casing powders pastes etc Clean the probes with water and dry it Before the probes are stored for a prolonged period of time it is recommended to grease them with any machine lubricant The reels and test leads should be cleaned with water and detergents and then dried The electronic system of the meter does not require maintenance 7 Storage The following recommendations must be observed to ensure proper storing of the device e Disconnect all the test leads from the meter e Clean the meter and all its accessories thoroughly e Wind the long test leads onto the reels e If the meter is to be stored for a prolonged period of time the batteries must be removed from the device e in order to prevent total discharge of the rechargeable batteries during prolonged storage charge them from time to time 8 Dismantling and utilization Worn out electric and electronic equipment should be collected selectively i e it must not be disposed with waste of another kind Worn out electronic equipment should be sent to a collection point in accordance with regulations related to Waste Electrical and Electronic Equipment Before the equipment is sent to a collection point do not attempt to dismantle any elements Observe the local
22. mperature inside the meter is exceeded 3 3 Measurement of resistance of protective conductors and equipotential bonding NOTE Calibrate the test leads when measuring very small resistance values or when using test leads different than the supplied 1 2 m and 2 2 m 9 4 Turn the meter Turn the rotary switch to the position Connect the tested facility to the S and E terminals The meter is ready for measurement 12 OPERATING MANUAL MRU 21 version 1 03 Press START Perform the measurement Read the measurement Q result Note The test current flows in one direction To obtain the result for both directions switch the test leads and perform the measurement again then calculate the arithmetic mean of both results Additional information displayed by the meter Excessive interference voltage gt 3Vrms The measurement is not possible Disconnect the source of interference rn gt ait and Interference voltage exceeds 50V A Disconnect the meter immediately Disconnect the voltage source before you reconnect the audio signal o gt 1990 The Rcowr measuring range is exceeded 1 3Vrms interference voltage during the measurement NOISE Measurement is slightly unstable The results may include an additional uncertainty nm and A and long audio signal Measurement is highly unstable Maximum allowed temperature inside the meter is exceeded
23. ode electrodes name Interruption in measuring circuit or resistance of test probes higher than 60 kO Check connections in the test circuit or reduce the probe and resistance by driving it into the soil again Er in the field below Cell and measurement result Uncertainty of the Re measurement caused by probes resistance exceeds 30 Reduce the probe resistance by driving it into the soil again or by dampening the soil in its End immediate vicinity gt 1 99kQ The RE measuring range is exceeded gt 50kQ Test probes resistance above 50kQ but below 60kQ Interference voltage above 10V or unstable measurement NOISE result or the measured voltages or currents are too low in relation to the noise nm 5 and A and Measured voltages or currents are too low in relation to the long audio signal noise or highly unstable measurement result The nm 3 o symbol is displayed instead of the result Maximum allowed temperature inside the meter is exceeded 3 2 Earth resistance measurement with the double lead method 2 If necessary adjust the voltage measurement according to section Ron Room Turn on the meter Turn the rotary switch to the 2p position 3P Connect the tested facility to the E and H terminals CATIV300V v I N 3 Nm IM TO 3 10 OPERATING MANUAL MRU 21 version 1 03 4 The meter is ready for measurement Uy Read the interference
24. regulations concerning disposal of packages worn out batteries and accumulators OPERATING MANUAL MRU 21 version 1 02 25 9 Technical specifications e The specified accuracy relates to the meter terminals e means a standard measured value 9 1 Basic data Measurement of resistance to earth Re Measurement method technical conforming with IEC 61557 5 Measuring range to IEC 61557 5 0 50Q 1 99kQ for Un 50V 0 680 1 99kO for Un 25V Display range Basic uncertainty 0 00 9 990 10 0 99 90 100 9990 2 m v 3 digits 1 00 1 99 0 01kQ e In the three lead method the meter displays the uncertainty caused by the probes resistance Such uncertainty can be also evaluated using the following diagram 100 0000 4 10 0000 4 Ry Re 3000 Ry Rg 1000 1 0000 Ry Rg 300 R Re 100 R Re 30 0 1000 R Re 10 Ry Re 3 R Current electrode resistance R Re 1 0 0100 4 R Earth resistance Ry Re 0 3 Additional uncertainty caused by resistance of probes 0 0010 26 10 100 1000 10000 100000 Voltage electrode resistance Rs Q El
25. result in its damage and may seriously endanger unauthorized user Using this manual does not exclude the need to comply with occupational health and safety regulations and with other relevant fire regulations required during the performance of a particular type of work Before starting the work with the device in special environments e g potentially fire risk explosive environment it is necessary to consult it with the person responsible for health and safety It is unacceptable to operate the following gt damaged meter which is completely or partially out of order ameter with damaged test leads insulation a meter stored for an excessive period of time in disadvantageous conditions e g excessive humidity If the meter has been transferred from a cool to a warm environment of a high level of relative humidity do not carry out measurements until the meter is warmed up to the ambient temperature approximately 30 minutes Before commencing measurements make sure the test leads are connected to the appropriate measurement sockets Do not operate a meter with an open or incorrectly closed battery compartment or power it from sources other than those specified in this manual The inputs of the meter are protected electronically against overload e g due to having been connected to a live circuit for all combinations of inputs up to 276V for 30 seconds Repairs may be carried out only by an authorized service point
26. s 3 6 8 after moving the voltage few meters UP placing it farther and closer to the 1 measured earth electrode If the measurement results differ by more than 3 the distance of the current electrode from the tested earth electrode should be considerably increased and the measurements should be repeated Note A The earth resistance measurement can be made when the interference voltage does not exceed 24V The voltage is measured up to 100V but above 50V is indicated as dangerous The meter must not be connected to voltages exceeding 100 V Particular attention should be paid to quality of connection between the tested facility and the test lead the contact area must be free from paint rust etc f resistance of the test probes is too high Re earth electrode measurement will include an additional uncertainty Particularly high measurement uncertainty occurs when a small value of resistance to earth is measured with probes that have a weak contact with earth such a situation occurs frequently when the earth electrode is well made and the upper soil layer is dry and poorly conductive In such a case the ratio of resistance of the probes to resistance of the tested earth electrode is very high and consequently uncertainty of measurement that depends on this ratio is also very high Then you can make a calculation according to the formulas given in item 9 to estimate the influence of measurement conditions
27. voltage on the auxiliary display Press START Perform the measurement 6 Interference voltage n LI V Read the measurement R result E UNA CUN j i Q Measured resistance c lt lt Note Factory calibration includes the resistance of the 1 2 m and 2 2 m test leads supplied Additional information displayed by the meter Excessive interference voltage 24V The measurement is not possible Disconnect the source of interference tu gt GL and Interference voltage exceeds 50V A Disconnect the meter immediately Disconnect the voltage source before you reconnect the audio signal o 1 j on Interference voltage exceeds 100V gt LI and Disconnect the meter immediately The symbol is A displayed instead of the interference voltage Disconnect the voltage source before you reconnect the and continuous meter audio signal o OPERATING MANUAL MRU 21 version 1 03 11 A Interruption in the test circuit gt 1 99kQ The RE measuring range is exceeded Interference voltage above 10V or unstable measurement NOISE result or the measured voltages or currents are too low in relation to the noise nm 5 and A and Measured voltages or currents are too low in relation to the long audio signal noise or highly unstable measurement result The nam 5 o symbol is displayed instead of the result Maximum allowed te
28. ype of resistance to earth measurement 1 Disconnect the tested earth electrode from the ol Tz gt installation of the facility 2 Ee nem Turn on the meter Turn the rotary switch to the Re 3p position 3 If necessary adjust the voltage measurement according to section 2 The current electrode driven into earth should be connected to H socket of the meter 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 03 7 5 SLT The meter is ready for measurement UJ 0 Head the interference voltage on the auxiliary display Press START Perform the measurement Interference voltage U 2 m a R Read the main measurement result SEEN j i Q Resistance of earth X N electrode Re Read the auxiliary results sequence as below by pressing lt lt and gt gt lt lt gt gt ji Ri wa W NAD o Resistance of current electrode O ay TL Resistance of voltage al electrode w o Additional uncertainty caused by resistance of 1 j the electrodes OPERATING MANUAL MRU 21 version 1 03 11 T Repeat the measurements step

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