OPERATING MANUAL MRU-105 AND MRU-106
Contents
1. 8 seconds e resistance using the four pole technique 16 seconds e earth electrodes resistance using the three pole and four pole method 16 seconds e earth electrodes resistance using the three pole method with clamps 20 seconds EE VE CTHCIOTINEERREROTRME UE 16 seconds A 295 x 222 x 95 mm Mass of the meter with a NiMH battery pack approx 2kg Operating temperature 0 40 C sea zy 20 80 Battery charging 1 10 35 23 2 C Storage 1 20 C 60 C Idle time to auto off 2 minutes Quality standard eicit tineis design and manufacturing ISO 9001 compliant 11 2 Manufacturer The manufacturer of the device provides all warranty and after warranty repairs SONEL S A ul Wokulskiego 11 58 100 widnica 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 can by carried out only by the manufacturer 32 SONEL S A Wokulskiego 11 St 58 100 Swidnica Poland a 48 74 85 83 860 48 74 85 83 800 fax 48 74 85 83 808 http www sonel pl e mail export sonel pl2. 7 12 2 Storing the Measurement Results into the Memory The memory write mode is active from the moment it is turned on until the device is switched off or the measurement function is changed Storing a result is possible only when the instrument dis plays the result of the recent measurement or one of the components of the result selected with the SEL key In any case only the main measurement result the resistance the earth electrodes re sistance Re or soil resistivity p is written into the memory 1 Turn on the memory write mode by pressing the key 10 gt The auxiliary display field of 24 that shows the current memory cell address will start flashing If in the current memory cell there is already a result stored the memory cell number will flash alternately with two horizontal dashes 2 Write the measurement result to the current cell pressing the key 10 gt Displayed symbol 28 3 will confirm that the data was stored in the memory and the current memory cell address will be in cremented by 1 24 Alternately 1 Turn on the memory write mode by pressing the key 10 gt The auxiliary display field of 24 that shows the current memory cell address will start flashing If in the current memory cell there is already a result stored the memory cell number will flash alternately with two horizontal dashes 2 Using the keys 11 A 12 w select a memory cell numbe
3. 26 6 1 2 Errors Related to the Resistance of 4 26 8 1 3 Information Related to Detected Lack of Connections Continuity 27 8 1 4 Information Related to Noises 220000000000 27 8 1 5 Information Related to Clamps Calibration sees 28 8 1 6 Battery Status Information eese eene nre 28 8 2 MESSAGES INFORMING ABOUT ERRORS ENCOUNTERED DURING THE SEEESTESTS ae O GO In n EE ee AS 29 8 3 BEFORE YOU SEND THE DEVICE FOR 5 29 9 CLEANING AND MAINTENANCE 2200 020000000000000000000000000000000000000000eo0a00w000 30 10 DECOMMISSIONING AND RECYCLING 202 02200 00000000000000000000000000000000 30 11 APPENDICES we 30 11 1 TECHNICAE SPECIFICATIONS oz o eee nes 30 112 MANUFACTURER did 32 1 Preface Thank you for choosing our MRU 105 MRU 106 earth resistance meter The MRU 105 MRU 106 meters are a modern high quality measurement devices that are easy and safe to operate Before use please familiarise yourself with this manual It will help you avoid any measurement errors and operating problems In this instruction we use three types of warnings They are shown as a framed text and describe possible hazards for either the user or the device Texts that start with the word WARNING describe a life threatening or hazardous situation that can result if the instru
4. OPERATION MANUAL EARTH RESISTANCE METERS MRU 105 amp MRU 106 SSner OPERATING MANUAL EARTH RESISTANCE METERS MRU 105 AND MRU 106 Version 1 5 18 06 2014 CONTENTS 1 AAA CC 5 2 INTRODUCTION z id i 6 3 SAFETY sscscsinsscssessscedensonsesessieteosasensssensssdecesvenseonntsodnssssasivosasscdesentessatesbacdesnsentassosessne 6 4 DESCRIPTION AND FEATURES ccsssscssscesssscssccssssssssscesssssssccsssesssssssssssees 7 4 1 MRU 105 MRU 106 15 0400 40 0 00000 7 4 2 STANDARD ACCESSORIES ne len sac veteres 7 4 3 OPTIONAL ACCESSORIES ccsssscsccececeesssscaecececeesesseaececececsessaaecesececsessaaeeeeeeeesenses 7 4 4 TERMINALS AND KEYPAD 8 4 4 1 Terminals ERES 8 4 4 2 Keypad o A ea UE EUROS 9 4 5 LIQUID CRYSTALS DISPLAY 1 2 2 2 2 0 2020 000000000000 10 4 6 BUZZER uer er ear n dM 12 4 7 TEST LEADS AND PROBEG sssessssccececsesesececececsesensececececeesenseaeeecececsessaseeeeeeees 13 4 8 TESTOLAMPS 13 5 STORAGE Dc 13 6 BEFORE YOU START seo tessera EO 13 7 OPERA VH LOCO 14 7 1 PREPARING THE DEVICE FOR 14 7 2 POWER SUPPLY RECHARGEABLE BATTERIES 14 72 1 Disposable Reusable Batteries Replacement esses 15 7 2 2 Charging the Battery Pack countries 16 7 253 General principles of
5. Test terminal S Terminal to connect the voltage electrode during resistance earth resistance and resistivity measurements 3 Test terminal ES Terminal to connect an auxiliary voltage electrode during soil resistivity measurements using a four pole technique This terminal is also used for resistance measurements using the two and four pole techniques 4 Test terminal E Terminal to connect tested grounding while performing earth resistance measurement and to connect one of the outer most electrodes while measuring soil resistivity 5 Clamps terminal Terminal to connect test clamps for testing multiple electrodes without disconnecting the earth electrode tested 40 Mains power supply socket Socket for connecting power supply for the battery charger 43 USB port Communications port to connect a USB cable 4 4 2 Keypad 6 Key 5 e Turns the power supply on and off After the power is turned on the screen displays all digits and symbols test of the display Holding 14 BAT or 10 gt key pressed activates special functions o Key 14 BAT battery discharge function o 10 activating data transmission mode 7 Rotary mode switch Measurement mode selection e Re2p two pole earth resistance measurement three pole earth resistance measurement Re4p four pole earth resistance measurement Re3p R three po
6. a EQ The resistance measured is FICS ES US AGO greater than 20kQ 8 1 2 Errors Related to the Resistance of Electrodes Display Panel State Cause Resolution DOAA The RH electrode re Try to improve the con A OG BON sistance is greater than tact of the electrode with LIMIT UN 50kQ soil e g by moistening R its surrounding H Does The Rs electrode to improve the con A OOGO 900 sistance is greater than tact of the electrode with LIMIT N 50kQ soil e g by moistening R its surrounding 4 00000 LIMIT Ny Re IE 01 14 009 Additional measurement ror due to the ratio of elec trodes resistance to the Re resistance is greater than 30 The resistance of elec trodes RH and Rs needs to be decreased 26 8 1 3 Information Related to Detected Lack of Connections Continuity Display Panel State Cause Resolution f a The instrument detected lack of continuity of the connections between the electrodes whose symbols are flashing Check the connections to the electrodes indi cated by flashing sym bols OO eo f a The instrument detected lack of continuity of the connections between the electrodes whose symbols are flashing if the clamp symbol flashes they might be connected incorrectly or the clamps current is too low for a successful meas urement Check if the measure ment
7. nect the device to voltages above this value 7 1 Preparing the Device for Work Before commencing the measurements e Make sure that the battery condition will allow you to complete the task e Check while uncoiling the test leads that the leads insulation is not damaged e Check that there is no possibility of leads or electrodes coming in contact with live wires WARNING Using test leads that are incorrect or have damaged insulation can cause electrocution WARNING You must not use the device with open or partially closed battery compartment and you must not use any power sources other then those specified in this manual WARNING You must not leave disconnected leads while some of them remain connected to the instal lation being tested You must not leave the device unattended while it is connected to tested installation WARNING Do not use a device that was stored for a prolonged period of time in unsuitable e g hu mid conditions If the device was moved from a cold to hot environment do not carry out any measurements until the device reaches the ambient temperature approx 30 minutes 7 2 Power Supply rechargeable batteries MRU 105 and MRU 106 is equipped with a battery pack and a charger The battery pack sits in the battery compartment Battery charger is installed inside the meter and can be used only with a proprietary NiMH battery pack 14 Note MRU 105 and MR
8. Figure 2 Liquid crystals display of the MRU 105 MRU 106 Test terminals symbols Indicates the test leads that should be connected for the test 8 clamps Indicates selection of the multiple electrodes resistance test using clamps or the clamps calibra tion mode Unit and type of the displayed value V volts voltage Q kQ ohms kilo ohms resistance kam ohm meter kiloohm meter resistivity m meters distance Measurement result display field Symbols of the measured and displayed values Re earth electrode resistance Rh current electrode H resistance Rs voltage electrode S resistance Un noise voltage 21 22 23 24 25 26 27 28 E additional error due to probes resistance E HI A A a PES po N 4 a gt Err sa za WY 30 gt 36 3 L na 37 gt gt gt 4 LU TL A gt gh 4 gt Figure 3 Messages and symbols displayed by MRU 105 MRU 106 CAL calibration Indicates selection of the clamps calibration mode BAT batteries discharged Replacement of the disposable batteries or recharge of the rechargeable batteries required COMM PC data transmission mode Auxiliary display field A warning Emphasises the importance of the displayed error information signals a need to refer to the operating manual LIMIT
9. One of the parameters is outside of the range Two dots no data in the current memory cell Lade writing into the memory 11 204 dEL erasing the memory 30 F no continuity between electrodes Resistance between the electrodes whose symbols are flashing is too high or the clamps cur rent too low nri 31 LIFL measurement range exceeded 32 batteries flat The device is unable to work reliably It will switch off automatically 3 minutes after the symbol is displayed Additionally a long audible signal will be produced 33 CAL successful clamps calibration 84 Err Error an error occurred during test clamps calibration The symbol may be displayed together with the symbol LIMIT and flashing symbols of elec trodes or clamps 35 d subsequent measurements dispersed too broadly Results of subsequent measurements of the same parameter differ considerably 36 H noise current too high na 37 battery pack not present in the instrument 38 ch 5 NiCd battery pack discharged 39 Currently selected memory cell is being used 41 LED battery charging indicator 42 Lugs to attach carrying straps 4 6 Buzzer Warning signals Continuous audible signal Noise voltage Un greater than 40V The meter is designed to operate with noise voltages not exceeding 40V You must not con nect the devi
10. be inserted in the way indicated on the diagram located inside the recess Insert ing the batteries incorrectly will not damage the instrument or the batteries but will prevent the meter from functioning 4 Replace the screws securing the lid Figure 4 Opening the battery compartment in MRU 100 Family meters 15 7 2 2 Charging the Battery Pack Connecting the power cable to the mains will automatically start the battery charging process while disabling the instrument The charger recognises whether the battery compartment contains disposable or rechargeable batteries An attempt to recharge disposable batteries will fail NiMH battery pack is charged using a fast charging method this results in charging time to be limited to approximately 3 hours During the charging process the temperature of the NiMH battery pack voltage change rate and charging current are monitored While charging is in progress a green LED diode flashes with the frequency of approx 1Hz Completion of the charging procedure is sig nalled with the LED being solid on Note If the batteries are almost completely discharged at the beginning of the charging process the LED will be solid on Note Due to faults in the mains supply the charging process can be completed prematurely In such case disconnect the device and restart the charging procedure Abnormal conditions no voltage damage to the battery pack overheating etc are
11. clamps calibration incorrect type of clamps or the clamps damaged Check quality of connec tions and or replace the clamps 29 9 Err Measurement error too large after clamps calibra tion Try to calibrate the clamps again paying particular attention to placing the lead in the centre of clamps jaws 29 Err Current didn t flow in the lead in which the meter forces the current flow Check connections eq Err No current in the clamps circuit Check the connection between the clamps and the instrument and make sure that the clamps are placed on the tested lead 8 1 6 Battery Status Information State of the display Cause Procedure Battery cells or NiMH bat tery package discharged Replace the disposable batteries recharge the reusable batteries BAT Batteries too low to ensure Replace the disposable proper functioning of the batteries or recharge device the reusable batteries zk h H Tried to charge the third party rechargeable or dis posable batteries There is no possibility to charge disposable bat teries Build in charger is working only with battery pack WAAKU05 28 8 2 Messages Informing About Errors Encountered During the Self Test MRU 105 MRU 106 instruments are frequently subject to strong electromagnetic fields which can have an impact on
12. cycle if none of the conditions described in chapter 7 4 exists During the measurement the main result field 19 of the LCD displays characters symbolising the progress of the measurement while in the field 20 the currently measured parameter type is shown After the measurement is com pleted the measured resistance R is displayed together with the resistance of the earth electrode Re or the soil resistivity p The remaining test parameters the resistance of the test probes Rh and Rs can be displayed by pressing the key 9 SEL Note Displayed value of the additional error is a sum of the probe resistance error and the er ror of the ratio of the tested circuit resistance to the resultant resistance Errors are derived from the measured values If the error calculated in this way exceeds 100 the symbol OFL is displayed The meter automatically selects the measurement range for each mode 7 6 Two pole Method of Resistance Measurement Two pole method is the most common technique for measuring resistance 1 Connect the test leads to the terminals 2 and 3 labeled S and ES respectively Fig 6 2 Set the rotary switch 7 to position RE 2p 3 After connecting the resistance to be tested press the key 8 START the instrument will start the test cycle 4 Read the result The result of the measurement is a sum of the resistance to be measured and the test le
13. diagram is correct Repeat the multiply earth electrode test after disconnecting it 8 1 4 Information Related to Noises Display Panel State Cause Resolution Un i LI LIF L The noise voltage due to the distribution of the po tential in the soil exceeds 40V Measurement of soil resistance will not be pos sible The meter emits an acoustic signal Disconnect the meter from electrodes immedi ately Before connecting the meter again to the tested circuit switch off the source of the cur rent Un 00 10 3 Ev 1005 00 The noise voltage due to the distribution of the po tential in the soil exceeds 24 V Measurement of soil resistance will not be pos sible Switch off the source of the current causing the noise Try to relocate the probes O88 LIMIT y Hi d Differences between sub sequent measurements too large Check the stability qual ity of connections The situation can also be caused by strong noises A OO pO H During the measurement of Re RH or Rs the disturbing current too large Can be caused by too high equalizing currents in the tested earth elec trode 27 8 1 5 Information Related to Clamps Calibration Display Panel State Cause Resolution Q Err Inconsistencies between subsequent measurements during
14. in Om e measurement of resistance using a two or four pole method e ability to perform measurements of multiple electrodes using a three pole method without discon necting earth electrodes tested using clamps e checking the noise voltages alternating and direct current and automatic termination of the re sistance measurement when the noise is too high e checking earth electrodes resistance before commencing the measurement to provide proper measurement accuracy memory for 300 measurements and an ability to transfer the data to a PC a large clear backlit LCD display ergonomic design power supply rechargeable NiMH battery pack or disposable R14 batteries built in battery charger battery status monitor Automatic shut down AUTO OFF when the device not in use Hermetic housing with a flip up lid Robust and ergonomically designed accessories supplied in a carry case 4 2 Standard Accessories The device is supplied in a kit that contains e MRU 105 MRU 106 meter of measuring conductors 50 metre yellow reeled cable WAPRZO50YEBBSZ 25 metre red reeled cable WAPRZO25REBBSZ 2 2 metre black cable with pin plugs WAPRZ2X2BLBB 1 2 metre yellow cable with pin plugs WAPRZ1X2YEBB Black crocodile clip KO1 WAKROBL20K01 Yellow test prod with banana socket WASONYEOGB1 30 cm earth contact probes MRU 105 and MRU 106 2 pcs WASONG30 L2 carrying case for the meter and its accessories WAF
15. of this manual in order to avoid errors that can result in a safety hazard or in an incorrect assessment of tested installations More information related to safety issues can be found in chapter 3 Safety Before you use the device for the first time read carefully chapter 6 Before You Start If the device causes any problems refer to chapter 8 Trouble Shooting All information on how to use the device is located in chapter 7 Operations 3 Safety MRU 105 MRU 106 instruments are designed do test the safety of electrical installations Therefore to ensure that the instrument is used correctly and that obtained results are reliable you need to adhere to the following rules Before starting to use the meter you have to become thoroughly familiar with this manual The device should be operated only by persons holding appropriate qualifications and who at tended appropriate occupational health and safety training It is not acceptable to o Usethe meter that is damaged in any way o Useleads with damaged insulation o Use the meter stored in inappropriate conditions e g high humidity for a prolonged period of time Before commencing a measurement select the desired mode and make sure that the test leads are connected to the appropriate terminals Repairs can be performed by an authorised service agent only Additional points to remember Symbol BAT appearing on the display panel indicates insufficient power supply
16. socket located in the horizontal section of the probe or through the reel lock if the lead plug is inserted into the socket on the reel If while in the field the lead plug becomes damaged the lead can be attached to the probe using an M5 screw after the insulation is stripped from the wire To carry out earth resistance measurements it is necessary to obtain an additional 25m test lead and two extra probes 48 Test Clamps Test clamps are provided as an option for MRU 105 MRU 106 meters They are used to meas ure the current in earth resistance tests using multiple electrodes without disconnecting 5 Storage When storing the device you should Disconnect all leads from the device coil the long test leads onto the reels Carefully clean all probes and other accessories Ensure that the device and all accessories are dry Ensure that the disposable batteries are removed rechargeable batteries are removed and dis charged if the device is not going to be used for a prolonged period of time 6 Before You Start After the purchase Check the contents of the packaging charge the NiMH battery pack or insert disposable batteries into the meter calibrate the clamps 13 7 Operations You need to get familiar with this chapter as it describes test diagrams testing methods and basic rules to interpret obtained results CAUTION The meter is designed to operate with noise voltages not exceeding 40V You must not con
17. them periodically to prevent ageing of components influencing the measurement accu racy Calibration is recommended after purchasing the clamps separately for the meter or after the clamps were replaced with the new ones The calibration is performed by setting the rotary switch 7 to CAL R The test terminals H 1 and E 4 should be connected to each other with a 1 2m test lead and the clamps should be placed over the cable Make sure that the cable passes through the middle of the clamps After pressing the key 8 START the meter determines a adjustment factor for the clamps connected to the instrument The factor is stored in the memory until the next calibra tion is performed and regardless of the power status of the meter During calibration process the following errors can occur Error Symbol Displayed Situation Current is not flowing 34 together with the The test lead not connected to proper ter through the test lead con symbols of sockets in the minals of the meter or lead broken necting sockets H and field 16 E Current in the clamps cir 34 together with flash Clamps not placed over the lead connect cuit is not flowing ing symbol 17 ed to terminals H 1 and E 4 or not connected to the instrument Inconsistent results of B4 F and 25 4 Conne
18. using nickel metal hydride Ni MH accumulators 16 7 3 CALIBRATION OF TEST CEAMPBS ddd aiw A e dioda 17 7 4 CONDITIONS FOR PERFORMING TESTS AND OBTAINING CORRECT RESULT 18 7 5 PERFORMING A MEASUREMENT AND OBTAINING READINGS FOR INDIVIDUAL COMPONENTS OF THE RESULT esses 19 7 6 TWO POLE METHOD OF RESISTANCE 19 77 FOUR POLE METHOD OF RESISTANCE MEASUREMENT eene eren 20 7 8 EARTH RESISTANCE MEASUREMENT USING THREE POLE METHOD 20 7 9 EARTH RESISTANCE MEASUREMENT USING FOUR POLE METHOD 21 7 10 MULTIPLE EARTH ELECTRODES RESISTANCE MEASUREMENT WITHOUT DISCONNECTING THE MEASURED GROUND ELECTRODES USING CLAMPS 22 7 11 SOL RESISTIVITY 23 7 12 MEASUREMENT RESULTS 24 7 12 1 Retrieving Results from the Memory eese nene 24 7 12 2 Storing the Measurement Results into the Memory esses 24 7 12 3 Deleting the Contents of the Memory seen 25 7 13 TRANSMITTING eene en 25 PC Connectivity Kit use abest 25 7 13 2 Connecting the Meter to a Computer essen 25 8 TROUBLESHOOTING eese esses eee ense tasse ta sens enses ense 26 8 1 WARNINGS AND MESSAGES DISPLAYED BY THE 26 8 1 1 Measurement Range Exceeded
19. 2rdRe utilised in Wenner s measurement method This technique assumes equal distances between electrodes V Figure 11 Soil resistivity measurement 1 Electrodes driven into the soil in a straight line and at equal distances from each other are con nected to sockets 1 2 3 and 4 labelled with letters H S ES and E respectively 2 Set the rotary switch 7 to position p 3 Press the key 8 START 4 The displayed distance between electrodes can be changed using the arrow keys 11 and 12 5 Press the key 8 START 23 6 Read the soil resistivity the resistance Re of the space between the electrodes S and ES and the resistances Rs and Ru You can toggle between values shown on the display 19 main field by repeat edly pressing the key 9 SEL Note It is assumed in the calculations that the distances between test electrodes are equal Wenner s method If this is not the case the measurement of earth electrodes resistances is to be performed using the 4 pole method and the subsequent calculations have to be done independently 7 12 Measurement Results Storage MRU 105 and MRU 106 meters are equipped with a memory that can hold 300 measurement results A single result is saved into a location called a memory cell Each measurement result can be saved in an arbitrarily selected
20. U 106 works only with SONEL NiMH 7 2V 3Ah battery pack The batteries are supplied not charged They should be charged before the first use Using third party NiCd NiMH R14 batteries will result in a message 22 BAT being displayed The charger will not work with R14 NiCd NiMH batteries either 7 2 1 Disposable Reusable Batteries Replacement MRU 105 and MRU 106 meter is supplied with either NiMH rechargeable battery pack or a five disposable R14 battery cells alkaline type battery cells are recommended Batteries are placed in a recess in the bottom part of the housing WARNING Before replacing of the NiMH battery package remove the measurement leads and the mains cable of the charger out of the sockets Opening the meter housing with the charger connected to mains can be a cause of an electric shock CAUTION If the batteries leaked inside the compartment the device should be sent to an authorised service agent Discharged batteries are signalled by the message 22 BAT or 32 bRE It is then necessary to replace the batteries with the new ones To do it follow the procedure below 1 Remove all leads from sockets and switch the meter off 2 Remove four screws securing the battery compartment lid located at the bottom of the hous ing and remove the battery compartment lid 3 Replace all batteries Battery cells 5x R14 or NiMH battery pack type SONEL NiMH 7 2V 3Ah should
21. UTL2 5 batteries R14 Service manual USB cable WAPRZUSB Meter carrying harness WAPOZSZE1 Calibration certificate 4 3 Optional Accessories Additional accessories that are not a part of the standard kit can be purchased from the manu facturer or from suppliers e Cable reel WAPOZSZP1 e 80 earth contact probe WASONG80 clip WAZACIMA1 L3 carrying case for 80 cm probes WAFUTL3 Measuring clamps C3 WACEGC30KR NiMH 7 2V 3Ah battery pack WAAKUO5 Calibration certificate LSWPLMRU105 106 SONEL Electric measurements software aiding preparation of complete measurement docu mentation WAPROSONPES Software generating drafts electric installation schematic diagrams SONEL Schematic WAPROSCHEM Measurement calculation software SONEL PE Calculations WAPROKALK 4 4 Terminals and Keypad Layout 5 MRU 105 5 El L Figure 1 Front panel of the MRU 105 and MRU 106 meter 4 4 1 Terminals The meter is designed to operate with noise voltages not exceeding 40V You must not con nect the device to voltages above this value CAUTION Test terminal H Terminal to connect the current electrode during resistance and resistivity measurements
22. ads resistance The impact of the leads resistance on the final result can be eliminated by using a four pole technique or by carrying out another measurement with the test leads short circuited and by subtracting the test leads resistance from the result obtained originally Rx Figure 6 Two pole method of resistance measurement 19 7 7 Four pole Method of Resistance Measurement The instrument enables also measurements of resistance using the four pole technique This can considerably decrease errors caused by test leads resistance This is important if the resistance measured is of a small magnitude 1 Connect four leads to terminals 1 2 3 4 labeled H S ES and E respectively 2 Connect the measured resistance so that the leads hooked up to terminals H and S are both connected to one of the poles of the tested resistance while the leads connected to terminals ES and E Fig 7 are hooked up to the other pole 3 Set the rotary switch 7 to position RE 4p 4 Press the button 8 START 5 Read the result Rx Figure 7 Four pole method of resistance measurement 7 8 Earth Resistance Measurement Using Three pole Method The three pole method is the most basic technique for earth resistance measurement 1 Connect the investigated earth to
23. ce to voltages above this value CAUTION Long audible signal 12 after commencing the measurement by pressing key 8 START if the noise voltage exceeds 24V during the measurement no continuity of the test leads detected if any other abnormalities are detected LCD displays appropriate information completion of the memory erasure operation confirmation after pressing a button that has no function assigned in the currently used mode automatic shutdown AUTO OFF confirmation Confirmations an other signals Short audible signal Confirms a key was pressed Emitted always when the instrument can perform the operation assigned to that key Two short audible signals After successful completion of a measurement sequence Short signal short pause and three short audible signals e Confirmation that data was successfully stored in the current memory cell 47 Test Leads and Probes MRU 105 MRU 106 meters are equipped with a set of test leads The lengths available are 50m 1x 25m 2x and 1 2m 2x The 25m and 50m leads are supplied on reels which can be placed on the test probes to sim plify winding and unwinding of the leads For this reason the reels are equipped with a lock preventing the reel from slipping down the probe Among the standard accessories there are two test probes that can be driven into the ground A test lead is connected to a probe by inserting a banana plug into the
24. cell Consequently the user can at will assign memory cell addresses to particular measurement points perform measurements in any sequence and repeat the measure ments without losing other data Saved results are not erased after switching the meter off therefore they can be later retrieved or transferred to a computer Also the current cell and bank address will not be altered It is recommended to erase the memory after retrieving the data or before taking a new series of measurements that can be stored in the same cells as the previous ones Only the earth electrode resistance Re and soil resistivity p are stored in the memory The measured test electrodes resistance values can only be displayed on the screen immediately after the measurement has been done 7 12 1 Retrieving Results from the Memory The memory access mode can be turned on only momentarily by pressing the key 11 A or 12 w The mode switches off automatically after approx 4 seconds or after pressing either of the two keys In the auxiliary result field 24 the current memory cell address is displayed The memory cell contents is shown in the main result field 19 1 Set the cell number address to be accessed using the key 11 A and 2 Read the measurement result When two dots are displayed symbol it means that no re sults are stored in the cell In this mode it is also possible to erase the contents of all memory cells
25. ction of the clamps not stable subsequent measure ments incorrect clamps type or the clamps faulty The adjustment factor can 34 E and 26 LIMIT Current measurement error too high for the not be determined adjustment factor calculated repeat the calibration process 17 Figure 5 Preparing the instrument for clamps calibration 7 4 Conditions for Performing Tests and Obtaining Correct Result Before starting the measurements certain conditions have to be fulfilled The device will auto matically block the commencement of any test if any of the following conditions exists perform a measurement Situation Symbols Displayed Notes The noise voltage exceed 26 LIMIT and 20 Un ing 24V The noise voltage exceed 26 LIMIT and 31 FL Continuous audible signal gen ing 40V erated No test current detected 30 r together with the socket Probes required for the test not symbol 16 connected to the device or probes disconnected from the lead Situation Symbols Displayed Notes Clamps current too low to 80 r _ together with the blinking Clamps not connected or too 17 clamps symbol high multiple earth resistance of the tested circuit in comparison to the resultant resistance Resistance of the test 26 LIMIT together with the name Decrease the probe resistance probes exceed
26. ctions are not followed Wherever a CAUTION exclamation opens the framed text it describes a situation where non adherence to the manual can result in damage to the meter Possible problems that may occur are preceded with the word Note WARNING Before starting to use the device please read carefully this manual always follow all health and safety guidelines and comply with manufacturer s recommendations WARNING MRU 105 MRU 106 meters are designed to test earth resistance and ground resistivity Us ing the device for purposes other then those described in this manual can cause an injury to the operator and or can damage the device WARNING MRU 105 MRU 106 meters can be used only by qualified personnel who are certified to work with electrical installations Operating the instrument by a person who is not qualified can result in a hazardous situation and or can cause damage to the meter Note The manufacturer reserves the right to introduce changes to device s design accessories and specifications 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 2 Introduction This manual describes the MRU 105 and MRU 106 devices We recommend that you familiar ize yourself thoroughly with the contents
27. e manufacturer or from authorised distributors The software can be used with a number of SONEL S A instruments equipped with an USB port Detailed information on the software can be obtained from the manufacturer and its distributors 7 13 2 Connecting the Meter to a Computer 1 Connect the cable to an USB port of the computer and to the port 5 of the meter 2 If connection is made for the first time system will find appropriate driver If software is installed 2 Launch the software 3 Turn on the data transmission mode by switching the instrument on with the key 6 while hold ing the key 10 gt depressed until the display will show the symbol 23 The meter remains in data transmission mode as long as it stays switched on 4 Follow the software instructions 25 8 Troubleshooting 8 1 Warnings and Messages Displayed by the Meter MRU 105 MRU 106 instruments display warning messages that can be triggered by either mal function of the device or by non optimal external conditions In the following figures showing simplified images of the display the following convention is used e black colour for continuously displayed symbols e grey colour for flashing symbols contoured symbol is displayed depending on the situation that caused the error 8 1 1 Measurement Range Exceeded Display Panel State Cause Resolution a
28. ement of earth electrode re sistance Re will be burdened with an additional error Particularly large measurement errors are ob served when a small earth electrode resistance is measured with probes having a loose contact with the soil such situation takes place when the earth electrode is correctly installed while the upper layer of the soil is dry with poor conductivity In such conditions the ratio of electrodes resistance to the resistance of the measured earth electrode is quite high and so is the error depending on that ratio You can either do some calculations see the formula given in the appendix Technical data to eval uate the impact of the test conditions or you can use the graph see the same appendix You can al so improve the contact between the electrodes and the soil e g by moistening the place where the electrode sits in the ground with some water of by moving the electrode to another location Also the test leads should be checked for any insulation damage and for proper contact between the lead and the banana plug electrode must not be corroded or loose In the majority of cases the accuracy of measurements is sufficient However one should be aware of the magnitude of errors present in the measurement result 7 9 Earth Resistance Measurement Using Four pole Method If it is necessary to perform a measurement not distorted by the test leads resistance error the four pole method can be used Note For soil resis
29. h as twofold Lest the accumulators discharge excessively and to avoid the necessity of forming them it is recommended to charge them from time to time even if they are not used Modern and fast chargers detect both too low and too high temperature of accumulators and react adequately Too low a temperature should preclude charging which might cause irreversible damage 16 to the accumulator An increase of the temperature of the accumulator is a signal to finish the process of charging and it is a normal phenomenon However charging at a high room temperature not only reduces durability but also a faster increase of the temperature of the accumulator which will be not charged to its full capacity Please remember that in the case of fast charging accumulators are charged to approximately 80 of their capacity and better results may be obtained continuing the process of charging the charger operates then in the additional charging mode with low current and after next couple of hours the ac cumulators are fully charged Do not charge or use accumulators at extreme temperatures Extreme temperatures reduce the du rability of batteries and accumulators It is recommended to avoid placing devices powered from ac cumulators at hot places The nominal working temperature must always be observed 7 3 Calibration of Test Clamps The clamps purchased together with the meter should be calibrated before their use You can also calibrate
30. lamps Note Clamps are not a part of the standard kit they can be purchased additionally from the manufacturer or from suppliers MRU 105 MRU 106 device can be used for performing measurements of multiple earth elec trodes that is many ground electrodes connected into a single system e g earth electrodes of high voltage transmission poles without being disconnected Test clamps are used to enable the instru ment to determine what amount of the test current flows through the particular earth electrode L Figure 10 Measurement of the multiple earth electrodes resistance using the three pole method 1 Connect the investigated earth electrodes connect to terminal 4 labelled E Fig 10 2 Connect the current electrode driven into the ground at a distance exceeding 40 m from the inves tigated earth electrode to the socket 1 H 3 Connect the voltage electrode driven into the ground at a distance exceeding 20 m from the inves tigated earth electrode to the socket 2 S The investigated earth electrode as well as the current and voltage electrodes should be aligned 4 Connect the clamps to terminal 5 and attach the clamps below the point where the lead E is at tached 22 5 Set the rotary switch 7 to position RE 8 6 Press the key 8 START 7 Read the earth electrode resistance Re and the resistance
31. le measurement of multiple electrodes using test clamps e CAL calibration of clamps p measurement of soil resistivity 8 START key Launches the test sequence In the soil resistivity tests o first key press entering the distance between electrodes o second press test sequence launch 9 SEL key Displaying all values related to the most recent measurement Re earth resistance e Rs RH auxiliary electrodes resistance and additionally during soil resistivity measurements e Soil resistivity 10 Key gt writing to the memory e After completing the measurement the most recent results are displayed Activating the memory write mode e In the memory write mode moving the result to the current memory cell 11 12 13 14 e Inthe memory browse mode after cell 00 was selected Erasing the memory contents Key A increase Key w decrease soil resistivity measurements changing distance between electrodes Start the memory browse mode e memory browse mode changing the current memory cell address Key Y display illumination Turns the LCD display illumination on and off Key BAT Displays the battery charging status in percent points 45 Liquid Crystals Display LCD 16 17 18 19 20 10 sm p fu ly ar IL on
32. not sig naled You need therefore after the charging process is completed check the battery charge level by pressing 14 BAT 7 2 3 General principles of using nickel metal hydride Ni MH ac cumulators If the device is not used for a prolonged period of time remove the accumulators and store them separately Store accumulators in a dry cool and well ventilated place and protect them from direct sunlight The storage temperature in the case of prolonged storage should be kept below 30 C If accumulators are stored at a high temperature for a long time then the chemical processes that are occurring may lead to reduction of their durability NiMH accumulators are generally designed for 500 1000 charging cycles The accumulators reach their maximum efficiency once they have been formed after 2 3 charging and discharging cycles The most important factor that influences the durability of those accumulators is the discharging depth The deeper is the discharge the shorter their durability The memory effect in the case of accumulators is limited Those accumulators may be addi tionally charged with no serious consequences However it is recommended to discharge them com pletely after a couple of cycles During storage of Ni MH accumulators they are spontaneously discharged at the rate of approxi mately 3096 per month If accumulators are stored at high temperatures the process may be acceler ated as muc
33. ononcnnonononccnananenconononansanenonocas double EN 61010 1 and IEC 61557 compliant Metrological Cate Qory E M ad III 300V lt 2000m above sea level Ill 260V lt 3000m above sea level EN 61010 1 compliant Housing protection class in accordance with EN 60529 IP54 Maximum noise voltage AC DC at which the measurement is still performed Maximum measured noise Maximum resistance to noise current Test current frequency Test voltage CUTE 0 Maximum resistance of the test 50kQ Clamps low current Warnings GZ ASA ERR RIA 0 5mA Device power supply rechargable battery pack SONEL NiMH 7 2V 3Ah or alcaline disposable baterie R14 5x Charger power Supply 100 250V 50 60 Hz 100mA Batteries charge approx 3 hours Batteries discharge time in the discharge max 3 hours Number of measurements that can be performed with one set of alkaline batteries on average TRENER TPR 2600 50 2 measurements min Number of measurements that be performed with one set of rechargeable batteries wid elu pied E IE DM E ETON SRK 1300 5O 2 measurements min Time required to perform a measurement of e resistance using the two pole
34. ot in conformance with waste management guidelines Do not remove any components from electronic equipment before sending it to a waste depot Local legislation and guidelines regulating disposal of packaging and batteries should be followed 11 Appendices 11 1 Technical Specifications e in the description of the basic error denotes the displayed value Measurement of earth electrode resistance without using clamps Method used voltage and current measurement using probes in accordance with IEC 61557 5 Measurement range in accordance with IEC 61557 5 0 130 20 0kQ Range Resolution Basic error e Additionally errors due to probes resistance as per formula below should be considered Ry 1000 300000 Rg PIE 5 1077 Ry 1000 107 zc where Re Ru and Rs are the values displayed by the meter in Q The factor used in the formula above 5 107 is expressed in 1 0 30 Earth electrode resistance measurement using clamps Method used voltage and current measurement using probes in accordance with IEC 61557 5 and current measurement in a single circuit branch using a current transformer clamps Measurement range in accordance with IEC 61557 5 0 160 20 0kO Additionally errors due to the probes resistance as per the formula above should be consid ered In the case of a multiple earth electrodes the resultant earth resistance measured without clamps should be s
35. r 3 Write the measurement result to the current cell by pressing the key 10 gt Displayed symbol 28 3 will confirm that the data was stored in the memory and the current memory cell address will be incremented by 1 Writing into the cell 300 the last cell in the memory is signalled with additional long audible signal while the current memory cell number remains unchanged 7 12 3 Deleting the Contents of the Memory In the memory read mode the cell with 00 address has a special role No data can be stored in it However selecting it will cause the main display field to show the symbol 29 dEL which signals that the meter is ready to delete the entire contents of the memory The instrument starts erasing the memory after the key 10 Dis pressed During the process the display will show the memory cells addresses being erased After all the cells have been erased the instrument emits a long audible signal and exits the memory read mode setting the current memory cell number 1 as a default Note Erasing the memory contents causes irreversible loss of the stored results 7 13 Transmitting Data to a PC 7 13 1 PC Connectivity Kit To connect your MRU 105 106 to a PC you will need an USB cable standard equipment and appropriate software optional If the software was not bought together with the device it can be pur chased from th
36. r with an in correct code has been selected Check if the batteries are inserted properly or re place the disposable bat teries recharge the reus able batteries If the prob lem persists send the meter to the service Configure the program for the correct meter The transmission cable plug not fully connected to the meters port Correct the connection of the meter to the comput er The USB cable damaged Check the cable replace if necessary USB port damaged Repair the computer 29 9 Cleaning and maintenance CAUTION Use only maintenance methods recommended in this booklet by the manufacturer The housing of the meter should be cleaned with a soft damp cloth using a general purpose detergent Do not use any solvents or any abrasive cleaning agents Probes can be washed with water and dried out Before storing for a prolonged period of time it is recommended to apply to the probes any kind of machine grease Reels and test leads can be cleaned using water with some detergent added and then dried out Cover can be washed at a temperature not exceeding 40 C using standard washing products Do not dry clean or iron Electronic circuitry of the meter is maintenance free 10 Decommissioning and Recycling Decommissioned electrical and electronic equipment should be collected separately from any other types of waste Decommissioned electronic equipment should be sent to a recycling dep
37. s 50 of the probe upon field 20 of the by reinserting it into the ground display unit or by increasing the moisture of the soil around the probe Measurement range ex 91 BDFL ceeded Additionally the meter signals situations in which the result of a measurement cannot be recognized as correct Situation Symbols Displayed Notes Measurement error due to resistance of electrodes exceeding 3096 26 LIMIT together with the meas urement result Decrease the probe resistance by reinserting it into the ground or by increasing the moisture of the soil around the probe Batteries flat 22 BAT None of the meter functions is disabled however the results ob tained can be distorted by addi tional error of unknown magni tude 18 7 5 Performing a Measurement and Obtaining Readings for Indi vidual Components of the Result After switching the meter on with the key 6 OD and also after each change of the rotary switch position the LCD displays the noise voltage value If the voltage exceeds 24 V it will not be pos sible to perform the measurement In this situation it should be checked if the measurement leads are connected to the appliances connected to the mains or if there is no short circuit or arching present in the vicinity of the tested object The measurement starts after pressing the key 8 START The instrument executes the meas urement
38. s Rs and Rh of the test electrodes You can toggle between values shown on the display 19 main field by repeatedly pressing the key 9 SEL 8 Repeat the measurements as in point 6 and 7 with the voltage electrode moved a few meters away and then toward the tested earth electrode If the measurement results differ by more than 396 the distance from current electrode to the earth electrode should be increased and the measurements repeated When using the multiple earth electrode method to test the power line poles there is sometimes a need to determine not only the resistance of single ground electrodes but also the total resistance of the entire earth electrodes system After obtaining the component measurement results Re Rez Res Rea the total resistance of the system can be calculated from the formula 7 11 Soil Resistivity Measurement To measure the soil resistivity measurements used in preparation for establishment of an earth electrodes system or in geology a separate function measurement of soil resistivity p se lectable with the rotary switch has been provided From the metrological point of view this function is identical to the four pole earth electrode resistance measurement method However it has an addi tional procedure of entering the distance between the electrodes The result of the measurement is the soil resistivity value calculated automatically using the formula p
39. socket 4 labeled as E Fig 8 2 Connect the current electrode driven into the soil at a distance more than 40m away from the in vestigated earth electrode to the socket 1 H of the meter 3 Connect the voltage electrode driven into the soil at a distance more than 20m away from the in vestigated earth electrode to the socket 2 S Investigated earth electrode as well as the current and voltage electrodes should be aligned 4 Set the rotary switch 7 to position RE 3p 5 Press the key 8 START 6 Read the resistance Re measurement result and the test electrodes Rs and Rh resistances You can toggle between values shown on the display 19 main field by repeatedly pressing the key 9 SEL 7 Repeat the measurements as in point 5 and 6 with the voltage electrode moved a few meters away and then toward the tested earth electrode If the measurement results differ by more than 396 the distance from current electrode to the earth electrode should be increased and the measurements repeated Particular attention should be paid to the condition of the contact between the tested object and the test lead The contact point should be free from rust paint etc 20 gt 20m gt 20 gt 4 Figure 8 Three pole technique for earth electrode resistance measuring If the resistance of the test electrodes is too high the measur
40. the internal registers The device automatically checks some parameters and displays error messages E10 error in reading or writing the result and or settings to from the memory E51 error in voltage measurement circuit E61 error in current measurement circuit E88 error in reading the meter calibration data E99 error in the program memory of the microprocessor Error message can be also caused by external factors It is therefore recommended to switch the device off and then on If the problem persists send the device to an authorised service agent 8 3 Before You Send the Device for Repairs Before you send the device to a service agent you should contact the technical support to en sure that the problem is a result of a fault and is not caused by some other factors All repairs should be conducted only by service agents authorised by the manufacturer In the table below you will find the procedures that should be followed in a case of malfunction Symptom The meter doesn t switch on when the key 515 pressed The symbol BAT is dis played The symbol bRE is dis played and the instru ment switches off auto matically Fuzzy and random dis play of screen fragments During data transmission no communication can be established or communi cation is not error free Batteries discharged or improperly inserted NiMH battery package discharged In the configuration pro gram a mete
41. tivity measurements it is recommended to use the function p 1 Connect the investigated earth electrode to sockets 3 and 4 of the meter labeled E and ES correspondingly Fig 9 2 The current electrode driven into the ground at a distance of over 40 m from the tested earth elec trode connect to the socket 1 H 3 The voltage electrode driven into the soil at a distance of 20 m from the tested earth electrode connect to socket 2 S The earth electrode investigated as well as the current and voltage elec trodes should be aligned 4 Set the rotary selector 7 to position RE 4p 5 Press the key 8 START 6 Read the earth electrode resistance Re and Rs and Rh resistances of test electrodes You can tog gle between values shown on the display 19 main field by repeatedly pressing the key 9 SEL 7 Repeat the measurements as in point 5 and 6 with the voltage electrode moved a few meters away and then toward the tested earth electrode If the measurement results differ by more than 396 the distance from current electrode to the earth electrode should be increased and the measurements repeated 21 gt 20m Figure 9 Four pole method of earth electrode resistance measurement 7 10 Multiple Earth Electrodes Resistance Measurement Without Disconnecting the Measured Ground Electrodes using c
42. ubstituted for Re Also an error resulting from the ratio of the tested circuit re sistance to the resultant resistance calculated using the formula below should be taken into ac count Sina 2003 w where Rc is the value measured using clamps and displayed by the meter and Rw is the result ant resistance value both measured in O The factor used in the formula above 0 03 is ex pressed in Q Measurement of soil resistivity Method used voltage and current measurement using probes in accordance with IEC 61557 5 in dependence uncertainty of Re measurement using 1 00 9 99 kam 0 01 kam EC aur 10 0 99 9 kOm RO 100 999 kom Errors listed above do not take into account an error due to electrodes resistance calculated from the above formula Additionally errors due to probes resistance as per the formula above should be considered Measurement of auxiliary electrodes resistance Ru and Rs Measurement errors of Rs and Ru resistances when not using clamps 5 of the total of the displayed values Re Rs Ru Measurement errors of Rs and resistances when using clamps 10 of the total of the displayed values Re Rs Ru Noise voltage measurement DC AC Measurement method full wave rectification Internal resistance approx 2MQ 0 40 V 10 w w 1 digit 31 Other technical data a b c x N lt CL Insulation type omocccconn
43. voltage and sig nals a need to replace the batteries Measurements obtained while the power supply voltage is too low are burdened with unpredicta ble additional errors and must not be used to assess the safety of the tested installation CAUTION The meter is designed to operate with noise voltages not exceeding 40V You must not con nect the device to voltages above this value CAUTION Devices terminals are protected against overload e g when the meter is mistakenly con nected to the mains for any combination of input terminals the protection is up to 276V over a period of 30 seconds WARNING 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 4 Description and Features 4 1 MRU 105 MRU 106 Characteristics MRU 105 MRU 106 instruments are designed to measure earth resistance and soil resistivity Main features of MRU 105 MRU 106 instruments e measurement of earth electrodes resistance using a three or four pole method e 501 resistivity measurement with an ability to enter the distance between electrodes automatic calculation and display of the resistivity
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