"user manual"
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1. 300 V CAT IV Pollution degree 2 Degree of protection IP 40 Dimensions w x h x d 31 cm x 13 cm x 25 cm Weight REND E ERE E EN oh ls 2 8 kg without accessories with batteries Visual 95 yes L ETAT 320 x 240 dots matrix display with backlight Reference conditions Reference temperature range 25 C 5 Reference humidity range 40 RH 70 RH Operation conditions Working temperature range 10 C 50 C Maximum relative humidity 95 RH 0 C 40 C non condensing Storage conditions Temperature range 10 C 70 C Maximum relative humidity 90 96RH 10 C 40 C 80 RH 40 C 60 C Nominal altitude up to 2000 m RS 232 serial communication galvanic separated Baud ate dos eco coL een Od 38400 baud 1 stop bit no parity Connector standard RS232 9 D female 37 MI 3250 MicroOhm 10A Maintenance USB slave communication galvanic separated Baud 38400 baud Connector standard USB connector type og 1000 storage locations 512 Real time clock error 50 ppm Maximum2. 10 96 smoothed DC Test duration 1 s single mode Test 4 wire measurement Note a All data regarding accuracy is given for nominal reference environment condition and forward and reverse measurements a Inductive mode will introduce an undefined error if an EMF is present on the test object a The error in operating conditions could be at most the error for reference conditions specified in the manual for each function 0 1 of measured value 1 digit unless otherwise specified in the manual for particular function 36 MI 3250 MicroOhm 10A Maintenance 8 2 Measurement parameters Test Current 10A 1A 100 mA 10mA 1mA Max Power Output 20 W 2W 0 2 W 20 mW 2mW Output Voltage 3 Voc max 1 Voc max Limits 1 2 Table 8 2 Measurement parameters 8 3 General data Battery power supply 7 2 V DC 6 x 1 2 Voc NiMH type HR14 size Mains power supply 90 260 Vac 45 65 Hz 50 W 300V CAT II Battery charging time typical 5 h 3500 mAh Battery operation time Idle state ee gt 25 Measurements 21000 measurements of 200 mQ load 0 10 A test current amp 1s measurement duration Protection classification double insulation E Over voltage category
3. MicroOhm 10A MI 3250 Instruction manual Version 1 0 Code no 20 751 893 32 METREL Distributor Manufacturer METREL d d Ljubljanska cesta 77 1354 Horjul Slovenia web site http www metrel si e mail metrel metrel si C Mark on your equipment certifies that this equipment meets the requirements of the EU European Union concerning safety and electromagnetic compatibility regulations 2011 METREL No part of this publication may be reproduced or utilized in any form or by any means without permission in writing from METREL MI 3250 MicroOhm 10A Table of contents Table of contents T General descriptiOn eene ecu ssa Rat DUNS P DDR 5 1 1 i e coast cece ek Dales ach ces 5 2 Safety and operational considerations eec 6 2 1 Warnings and NOLES x eut 6 2 2 Battery and stat atia Sid da Song img ent ad d icd nct sd Std Pi 8 2 2 1 New battery cells or cells unused for a longer period 9 2 3 Standards applied icon ados op ope qoaa 10 3 Instrument Description Ru 11 3 1 Qperator PANG lads a Dd rad d Du 11 3 2 Connectors and Battery cover n i eeren reeet 12 3 2 1 Test leads connector essessessrsseseereeseeseesessessrserrseseeseeseeseese 12 3 2 2 Connector panel
4. 9 98 no Save results in Ant 20 198 2 29 9 OBJECT 004 R 25 9 Memory Free 79 9 Mode Single Auto Range Off Range 200m Current 10 Figure 4 3 Storing Menu Keys lt gt Selects Object number MEM Saves measurement result to selected object number and returns to the Measurement result screen ESC Returns to the Measurement result screen without save The instrument will beep in order to indicate that result is successfully saved into the memory Note a Every stored test result also includes date and time stamp dd mm yyyy hh mm 20 MI 3250 MicroOhm 10A Main menu 4 2 2 Recalling results To enter Recall results menu in Memory menu SELECT key should be pressed 05 34 12 04 91 nel _ 34 62 mo DT LL OBJECT 001 Ont 26 4 66 86 108 128 148 168 198 200mR No of results 3 3 R 3461m Ix 11 1A R 34 62 0 Measurement 2 2 14 04 2011 12 00 Mode 200m Figure 4 5 Recalled result screen Auto Range 10A Range Single Figure 4 4 Recall Menu Keys in Recall menu A Selects one of the following items Object No of results Decrees or increase the parameter SELECT Recalls result in selected location ESC Returns to the Memory Menu Keys in Recall result screen lt gt Toggles between the saved results under selected Object E
5. right side sisson 13 3 2 3 Connector panel leit side ice 14 dub LUNGGOSSODIBS idi em dou 15 3 4 Display organizatlOr 1 5 ete opa Uu a aaa TER ERR RE 16 3 4 1 Measurement result window dz ee ee exten ex ex ex ex ea ea eeu ene 16 3 4 2 Measurement control window 17 3 4 3 Message Window d A 0 O96 17 3 4 4 Battery and timeindicatiom 18 3 4 5 Baecklieht operation eo ones asa RS 18 M in Men iiio io oiii 19 4 1 Instrument Main IVC pls cin Lo e Ie eto i totes 19 4 2 Memory MENU eet X mr 20 4 2 1 Saving results ERREER E ER ERE E 20 4 2 2 Recallino eS UM es oou M MEE MEM UU E 21 4 2 3 Deleting FOSS 2 cocco neci o ORE ODE ERLE HEH ERLE 22 4 2 4 Clearing complete memory content 22 4232 Settings cuc esu teu esu tuu 23 4 3 1 Language selection cov on OU NO AINE RO SEO ORO NEN UR RO E RR 23 4 3 2 Communication selection an acini 23 4 3 3 Set Date EUER ME 24 4 3 4 Det CONAS MEE 24 4 3 5 Temperature 55 25 4 3 6 SEEDS S TT 27 4 3 7 Iriscrumerit A810 UE 2f 4 4 Help MCI ditio qr n
6. 10A Safety and operational considerations 2 Safety and operational considerations 2 1 Warnings and notes In order to maintain the highest level of operator safety while carrying out various tests and measurements Metrel recommends keeping your MicroOhm 10A instruments in good condition and undamaged When using the instrument consider the following general warnings Q The A symbol on the instrument means Read the Instruction manual with special care for safe operation The symbol requires an action If the test equipment is used in a manner not specified in this user manual the protection provided by the equipment could be impaired Read this user manual carefully otherwise the use of the instrument may be dangerous for the operator the instrument or for the equipment under test Do not use the instrument or any of the accessories if any damage is noticed Consider all generally known precautions in order to avoid risk of electric shock while dealing with hazardous voltages Do not use the instrument in supply systems with voltages higher than 300 V Service intervention or adjustment is only allowed to be carried out by competent authorized personnel Use only standard or optional test accessories supplied by your distributor Consider that older accessories and some of the new optional test accessories compatible with this instrument only meet CAT II 300 V over voltage safety rating This means that maximal allo
7. Inductive mode makes a single unidirectional measurement It is intended for measuring resistance on inductive objects Depending on the size of the inductive object testing times could be very short for small objects or very long for the larger high inductive objects Before the desired current for testing purpose can flow this energy requirement must be met W 1 2 LxI The range and current output is user defined Inductive measurement I t plot A Test Start Stop ME E 1201 t EE gt ta t UA ADC 1 t Figure 5 8 Inductive Mode leuc drach charging time depends on the size of the inductor Id eee discharging time same as the charging time or max 5min Note a The Inductive Mode can be primarily used for measuring Motor amp generator winding Power transformers Power inductors Wire and cable resistance Warnings a Do not touch the test object during the measurement or before it is fully discharged Risk of electric shock a When resistance measurement has been performed on an inductive object automatic discharge may not be done immediately a High voltage can appear on test terminals when measuring inductive object 33 MI 3250 MicroOhm 10A Communication 6 Communication The instrument can communicate with the HVLink PRO PC software The following action is supported Savedresults can be downl
8. for measurement control and laboratory use Part 1 General requirements EN 61010 031 Safety requirements for hand held probe assemblies for electrical measurement and test Note Immunity to radiated RF fields Field strength 10V m Modulation AM 80 1 kHz Current Operational Disturbance gt 0 25 Disturbance lt 0 25 Range conditions 1mA Range 2 100 MHz 500 MHz 500 MHz 1 GHz Note about EN and IEC standards a Textof this manual contains references to European standards All standards of EN 6XXXX e g EN 61010 series are equivalent to IEC standards with the same number e g IEC 61010 and differ only in amended parts required by European harmonization procedure 10 MI 3250 MicroOhm 10A Safety and operational considerations 3 Instrument Description 3 1 Operator s Panel The operator s panel is shown in Figure 3 1 below P vi MicroOhm 10A 070 Figure 3 1 Front panel Legend 1 START STOP Start or stop measurement Switches the instrument power on or off 2 ON OFF The instrument automatically turns off 15 minutes after the last key was pressed MEM Store recall clear tests in memory of instrument To enter set up mode for the selected function or to select the active 4 SELECT parameter to be set 5 6 Select an option upward downward 7 8 Decrease increase the selected parameter 9 ESC Exit the selected mode 10 LIG
9. higher than 8 V AC or DC are detected between test terminals There will be no warning if all terminals are at the same potential a PASS FAIL indication is enabled when limit is set Apply appropriate limit value for evaluation of measurement results MI 3250 MicroOhm 10A Safety and operational considerations 2 2 Battery and charging The instrument uses six alkaline or rechargeable Ni Cd or Ni MH battery cells Nominal operating time is declared for cells with nominal capacity of 3500 mAh Battery condition is always displayed in the upper right display part In case the battery is too weak the instrument indicates this as shown in figure 2 1 Figure 2 1 Discharged battery icon The battery is charged whenever the power supply is connected to the instrument The power supply socket is shown in figure 2 2 Internal circuit controls charging and assures maximum battery lifetime Figure 2 2 Power supply socket The instrument automatically recognizes the connected power supply and begins charging 09 16 Of Symbols Charging Indication of battery charging Figure 2 3 Charging indication a A When connected to an installation the instruments battery compartment can contain hazardous voltage inside When replacing battery cells or before opening the battery compartment cover disconnect any measuring accessory connected to the instrument and turn off the instrument Ensure that the battery cells are inse
10. lead resistance 100 mQ total Rieaa c4 Riead c2 38 MI 3250 MicroOhm 10A Maintenance 39 MI 3250 MicroOhm 10A Maintenance 40
11. points and inversely proportional to the resistance between them The mathematical equation that describes this relationship is U Voir U Voir gt R dampen 29 MI 3250 MicroOhm 10A Measurement 5 2 Resistance measurement Test can be started from the Measurement screen Before carrying out a test the parameters Mode Range and Current can be edited 20 09 OF 9 978 mo en 2 4 6 8 18 12 14 16 18 20m R 25 978m Ixz 10 78 R 5 977m Mode Single Auto Range Off Range 20m0 Figure 5 2 Resistance menu Test parameters for Resistance measurement Mode Single Automatic Continuous Inductive Auto Range Off On Range 2 MQ 20 200 2 Q 20 0 200 O 2 Current 10 A 1 A 100 mA 10 mA 1 mA Test circuits for Resistance measurement Figure 5 3 Measurement of Resistance Resistance measurement procedure Select the Measurement function Set the test parameters Connect device under test to the instrument see figure 5 3 Press the START STOP key to start the measurement Press the START STOP key again to end the measurement in continuous automatic and inductive modes Store the result by pressing MEM key optional 30 MI 3250 MicroOhm 10A Measurement 20 12 OF _ 9 9930 E 1 4 8 10 d2 14 de 18 20 R 25 9550 Ixz
12. through the measured resistance During measurement campaign this result is refreshed every few seconds After finishing measurement result is hold on screen until new measurement is started Amb shows the value of the ambient temperature that was measured with the temperature probe or was entered manually appears when the temperature compensation is turned on Ref shows the value of the reference temperature that was entered manually appears when the temperature compensation is turned on Dis shows the discharging time appears only in inductive mode 16 MI 3250 MicroOhm 10A Instrument description 3 4 2 Measurement control window Control window permit user to modify control measurement parameters Mode Single Auto Range Off Range 200m Current 10A Figure 3 9 Control window Mode allows user to select desired measuring mode It is possible to select one of following modes Single Automatic Continuous and Inductive See chapter 5 2 for more details Auto Range allows user to select or deselect automatic range selection Range allows user to select desired measuring range It is possible to select one of following ranges 2 20 mQ 200 mQ 2 0 20 O 200 0 2 kO Current allows user to select proper current for resistance measurement It is possible to select one of following currents 1 mA 10 mA 100 mA 1 A 10 A Notes a Auto Range is always deselected in Inductive mode a Resistance range d
13. 10 7 Nickel Ni 5866 6 99x10 Platinum Pt 3729 1 06x10 7 Silver Ag 3819 1 59x10 Zinc Zn 3847 5 90 107 Table 4 1 Temperature coefficient and resistivity 26 MI 3250 MicroOhm 10A Main menu 4 3 6 Set Limits With Upper and Lower limits the user is allowed to set limit resistance values Measured resistance is compared against those limits Result is validated only if it is within the given limits 08 21 Setup Limits Upper Limit 15 0 Lower Limit 085 Enable Limits Figure 4 14 Setup limits menu Keys lt gt Select the parameter to be changed A Decrees or increase the parameter ESC Returns to the Settings menu changes are stored automatically 4 3 7 Instrument info In this menu the following instrument data is shown a hardware version a firmware version a serial number a calibration date 20 19 Of Instrument Info Hardware ver 1 Firmware ver 1 10 build 175 Serial No 342156 Calibration date 12 1 2011 Figure 4 15 Instrument info screen Keys ESC Returns to the Settings menu 27 MI 3250 MicroOhm 10A Main menu 4 4 Help Menu The Help menu contains schematic diagrams for illustrating how to properly connect the instrument to the various test objects Keys in help menu A Selects next previous help screen ESC Returns to the Settings menu 2 Welding joint tl 4 Motor win
14. 113ma R 9 9920 Mode Single Auto Range On Figure 5 4 Example of Resistance measurement result Note a Consider displayed warnings before starting measurement 5 2 1 Single Mode Single mode makes a single bidirectional measurement The instrument will measure resistance in both directions thermal EMF elimination The main result displayed on the R R The range and current output can be automatically set or user defined Single measurement l t plot display is an average R Test Start gt l gt t 4 ADC ADC gt t Figure 5 5 Single Mode Note a The Single Mode can be primarily used for measuring Ralays Switches Connectors Bus bars Power distribution cable joints Welding joints 5 2 2 Continuous Mode Continuous mode makes continuous bidirectional measurements The instrument will measure resistance in both directions thermal EMF elimination and repeating the measurements until the STOP key will be pressed The main result displayed on the R R_ display is an average of the last bidirectional measurement The range and current output can be automatically set or user defined 31 MI 3250 MicroOhm 10A Measurement The measurement is started and stopped by the user Continuous measurement I t plot Test 4 Start 1 Sto
15. HT Turn the display backlight ON or OFF Instrument s RESET hold key for 3 s or more 11 MI 3250 MicroOhm 10A 2Binstrument Description 3 2 Connectors and Battery cover The MicroOhm 10 tester contains the following terminals Four banana safety sockets for connection of test leads Figure 3 2 Mains socket for connection of mains supply cable Figure 3 3 Communication terminals USB and RS232 Figure 3 3 Battery cover Figure 3 4 3 2 1 Test leads connector Figure 3 2 Test leads connector Legend 1 C1 2 C2 3 P1 4 P2 Current terminals Measuring inputs outputs Voltage terminals Warnings a Maximum allowed voltage between any test terminal and ground is 300 V a Maximum allowed voltage between test terminals is 300 V Use original test accessories only 12 MI 3250 MicroOhm 10A Instrument description 3 2 2 Connector panel right side Figure 3 3 Communication and mains connectors Legend Communication with PC RS232 port connector Communication with printer 2 USB connector Communication with PC USB 1 1 port 3 Mains connector Mains supply of the instrument and battery charger supply Warnings a Maximum allowed voltage between L N Mains connector is 300 V CAT II a Use original test accessories only 13 MI 3250 MicroOhm 10A Instrument description 3 2 3 Connector panel left side Figure 3 4 Measuring inputs out
16. Kelvin method to measure low resistances of Switches Relays Connectors Bus bars Power distribution cable joints Motor amp generator winding Power transformers Power inductors Rail track joints Wire and cable resistance Welding joints VVVVVVVVVVV Instrument can be powered from mains or internal rechargeable batteries It is designed and produced with the extensive knowledge and experience acquired through many years of of working in this field Available functions and features offered by the MicroOhm 10A meter Resistance measurement Four wire Kelvin method High Resolution measurement 24 Bit 2 A ADC Auto or Manual Range Wide measuring range 0 1 uQ 2 Adjustable test current 1 mA 10 A Temperature compensation Hi Lo limits Automatic thermal EMF elimination Four different measuring modes single continuous inductive automatic USB and RS232 communication High overvoltage category CAT IV 300 V VVVVVVVVV VV A 320x240 dot matrix LCD offers easy to read results and all associated parameters The operation is straightforward and clear to enable the user to operate the instrument without the need for special training except reading and understanding this Instruction Manual Test results can be stored on the instrument PC software HVLink PRO that is supplied as a part of standard set enables transfer of measured results to PC where can be analysed or printed MI 3250 MicroOhm
17. SC Returns to the Recall Menu 21 MI 3250 MicroOhm 10A Main menu 4 2 3 Deleting results To enter Delete results menu in Memory menu SELECT key should be pressed Single measurement or all measurements under selected Object can be deleted 18 44 Delete Menu OBJECT 001 No of results 0 0 Figure 4 6 Delete all measurements under selected Object Keys in Delete menu Selects one of the following items Object No of results Decrees or increase the parameter SELECT Enters Delete confirmation screen ESC Returns to the Memory Menu Keys in Delete confirmation screen SELECT Deletes result s in selected location ESC Returns to the Delete Menu without changes 4 2 4 Clearing complete memory content When selecting the Clear All Memory function in Memory menu all the memory content will be deleted Keys in Clear all memory confirmation screen SELECT Clears all memory content ESC Returns to the Memory Menu without changes 22 MI 3250 MicroOhm 10A Main menu 4 3 Settings menu In the Settings menu different parameters and settings of the instrument can be viewed or set 19 55 QE Settings Menu Communication R 232 Set Date and Time Set Contrast Temperature Compensation Set Limits Instrument Info Figure 4 7 Settings menu Keys Select the setting to adjust or view Language instrument language Communication commun
18. atically turned ON It can be turned OFF and ON by simply clicking the LIGHT 52 Note a If you press and hold the Light 25 key for approximately 5 s the instrument will RESET 18 MI 3250 MicroOhm 10A Main menu 4 Main menu 4 1 Instrument Main menu From the main menu of the instrument there are four options available Measurement Memory Menu Settings Menu and Help Menu 19 50 Of Main Menu Memory Menu Settings Menu Help Menu Figure 4 1 Instrument Main menu Keys Select one of the following menu items A Ay Measurement See chapter 5 2 Memory Menu Memory management see chapter 4 2 Settings Menu Setup of the instrument see chapter 4 3 Help Menu Help screens see chapter 4 4 SELECT Confirms selection 19 MI 3250 MicroOhm 10A Main menu 4 2 Memory Menu Measurement result with all relevant parameters can be stored into the instrument s memory The instrument s memory space is divided into 2 levels Object and Number of Results The upper Object level can contain up to 199 locations The number of measurements stored under single object location is not limited Memory Menu Recall results Delete results Clear All Memory 08 22 11 Figure 4 2 Memory Menu 4 2 1 Saving results After the completion of a test the results and parameters are ready for storing By pressing the MEM key the user can enter storing menu 49 52 08
19. ding t4 Cz Bs Figure 4 16 Examples of help screens 28 MI 3250 MicroOhm 10A Measurement 5 Measurement 5 1 Four wire Kelvin method When measuring resistance 20 Q it is advisable to use a four wire measurement technique Figure 5 1 for achieving high accuracy By using this type of measurement configuration the test lead resistance is not included in the measurement and the need for lead calibrating and balancing is eliminated A Ei Q Rwire aye e Rwire Rx 2 Rwire Ee MicroOhm 10A Rwire Figure 5 1 Four wire Kelvin method The measuring current is passed through the unknown resistance Rx using the C1 and C2 probes The placing of these probes is not critical but should always be outside the P1 and P2 probes The Voltage drop across the Rx is measured across P1 and P2 and these should be placed exactly at the points to be measured Note about poor connection a Most measurement errors are caused by poor or inconsistent connection of the object under test It is essential to ensure that the device under test has clean oxide and dirt free contacts High resistance connection will cause errors and may prevent the selected current to flow because of the high resistance of C1 C2 loop Note a Ohm s law states that the current through a conductor between two points is directly proportional to the potential difference or voltage across the two
20. ds based on petrol or hydrocarbons a Do not spill cleaning liquid over the instrument T 2 Periodic calibration It is essential that the test instrument is regularly calibrated in order that the technical specification listed in this manual is guaranteed We recommend an annual calibration Only an authorized technical person can do the calibration Please contact your dealer for further information 7 3 Service For repairs under warranty or at any other time please contact your distributor 35 MI 3250 MicroOhm 10A Technical specification 8 Technical specifications 8 1 Resistance measurement Accuracy 0000 0 2000 0 pO 0 1 uO 0 25 Rdg 0 01 FS D 00 000 20 000 ma 1 0 25 Rdg 0 01 FS 000 00 200 00 ma 10 pO 0 25 Rdg 0 01 FS 00 000 20 000 ma 0 25 Rdg 0 01 FS 000 00 200 00 ma 10 uQ 0 25 Rdg 0 01 FS 0 0000 2 00000 100 pO 0 25 Rdg 0 01 5 000 00 200 00 ma 10 0 25 Rdg 0 01 FS 0 0000 200000 100 pO 0 25 Rdg 0 01 FS 00 000 20 0000 1 0 25 Rdg 0 01 FS 0 0000 2 00000 100 pO 0 25 Rdg 0 01 FS sey 00 000 20 0000 1 0 25 Rdg 0 01 FS 000 00 200 000 10 0 25 Rdg 0 01 FS 00 00 20000 10 mO 3 1 Rdg 0 1 FS 0000 20000 100 1 Rdg 0 25 FS 0 000 2 000 10 1 Rdg 0 25 FS Table 8 1 Resistance measurement ranges and accuracy reference conditions Test current accuracy
21. eo Gi eh quide abre n Gilda D quoe pude belio edo ede PN pude be CA 28 9 et 29 5 1 Four wire Kelvin opes 29 5 2 Resistance lt lt lt lt lt lt lt 30 5 2 1 Single Mode pop sca MD I MI EE 31 5 2 2 Continuous Mode EO 31 5 2 3 A tomatie Mde RARE MM 32 5 2 4 Inductive Mode 0000000000919010 33 5 CommunicaltlI eee terere eee a EM 34 II CES 35 MI 3250 MicroOhm 10A Table of contents 7 1 pi i 35 7 2 F eriodic calibrallObou et Gus te lout aes 35 7 3 SEVICE moindre LAM LA 35 8 2 20 22 22 22 4 36 8 1 Resistance measurement 8 36 8 2 Measurement 37 8 3 General rz IC 37 MI 3250 MicroOhm 10A General description 1 General description 1 1 Features MicroOhm 10A MI 3250 is a portable 2 8 kg bidirectional low resistance ohmmeter using four wire
22. epends on selected current Example with selected 1 A current only 20 mO 200 and 2 ranges can be selected See table 8 1 for more details 3 4 3 Message window In the message field warnings and messages are displayed 05 16 21 No Battery No batteries or wrong polarity of inserted batteries 99 16 2 Charging Battery charging in progress Ci High voltage is present on measuring terminals Measurement in progress 17 MI 3250 MicroOhm 10A 2Binstrument Description Instrument is overheated Measurement process is disabled Battery supply voltage is low P1 P2 C1 or C2 terminal is not connected to the instrument or too high resistance is detected Measurement current and result is within defined limits Measurement current is out of defined limits Measurement result is out of defined high limit KW SN Lae Measurement result is out of defined low limit 3 4 4 Battery and time indication The indication indicates the charge condition of battery and charger connection El Battery capacity indication Low battery Battery is too weak to guarantee correct result Replace or recharge the battery cells Recharging in progress if mains supply cable is connected 02 26 Time indication hh mm Note a Date and time is attached to each stored result 3 4 5 Backlight operation After turning the instrument ON the LCD backlight is autom
23. erature compensation Temperature compensation calculation _ 1 a x ref _ temp R ref _temp amb _ temp 1 a x amb temp Legend Rie lt Compensated resistance calculated to the reference temperature Roo 101 Resistance measured at the ambient temperature Temperature coefficient of the measured object Cu Al user defined A Reference temperature which the measurement is referred to ref _temp C user defined Ambient temperature measured with the temperature probe or user defined amb temp c 25 MI 3250 MicroOhm 10A Main menu Example Ramb _temp 1 1 8 44mQ a 4100 ppm C AI ref temp 25 amb temp 40 C 1 arx ref temp 118 x Lt 4100 ppm C 25 2 R 1 a x amb temp 1 4100 ppm C 40 C ref temp tem 112 18 Measurement window shows the compensated value 21 19 D 0 41250 2 4 6 amp da 12 f4 16 18 20 20 390m6 b 1 040 Ref 25 0 C R 0 394 Amb 40 0 C Mode Single Auto Range Off Current Figure 4 13 Compensated result example This table shows the temperature coefficient of various materials at 20 C 68 F Material Symbol Temperature coefficient Resistivity a ppm C Om Aluminium Al 4100 2 82 107 3930 1 68x10 Gold Au 3715 2 44 107 Iron Fe 5671 1 0x
24. ettings menu changes are stored automatically Note a When using the instrument in a cooled environment contrast level should be decreased 24 MI 3250 MicroOhm 10A Main menu 4 3 5 Temperature Compensation The temperature compensation is used to adjust the measured resistance which depends on the ambient temperature to the value it would have at the reference temperature 24 09 1 24 40 1 Compensation Menu Coefficient Menu Cu 3930 Set Reference Temp 25 0 C Al 4100 ppm Temperature Manual User1 4460 ppm Set Ambient Temp 40 0 C User2 4000 ppm cC Coefficient Menu Figure 4 10 Compensation menu Figure 4 11 Coefficient menu Keys in Temperature Compensation menu Select the parameter to be changed Compensation Set compensation On Off Set Reference Temp Reference temperature value Ay lt Temperature gt Ambient temperature settings Manual Probe lt Set Ambient Temp gt Ambient temperature value lt Coefficient Menu gt Coefficient settings see figure 4 12 lt gt Decrees or increase the parameter SELECT Enters Coefficient menu ESC Returns to the Settings menu changes are stored automatically Keys in Coefficient menu A Select the parameter to be changed lt gt Decrees or increase the parameter ESC Returns to the Temperature Compensation menu changes are stored automatically Resistance measurement with the temp
25. ication port selection Set Date and Time date and time Set Contrast LCD contrast settings Temperature Compensation temperature compensation settings Set Limits limit values selection Instrument Info basic instrument information SELECT Confirms selection ESC Returns to the Main menu 4 3 1 Language selection The instrument language can be set Keys lt gt Toggles between different languages Note a No confirmation is needed to set the desired language 4 3 22 Communication selection The instrument communication port can be set Keys lt gt Toggles between 5232 and USB Note a No confirmation is needed to set the desired communication port 23 MI 3250 MicroOhm 10A Main menu 4 3 3 Set Date and Time To enter Date and Time menu SELECT key should be pressed Figure 4 8 Date and time menu Keys lt gt Select the parameter to be changed Decrees increase the parameter SELECT Confirms selection and returns to the Settings menu ESC Returns to the Settings menu without changes Warning lf the batteries are removed of the instrument the time and date will be lost 4 3 4 Set Contrast In this menu the contrast of the display can be set To enter Set Contrast menu SELECT key should be pressed 08 20 Set Contrast RENE 40 Figure 4 9 Set Contrast menu Keys lt gt Sets contrast value ESC Returns to the S
26. oaded and stored to a PC A special communication program on the PC automatically identifies the instrument and enables data transfer between the instrument and the PC There are two communication interfaces available on the instrument USB or RS 232 How to transfer stored data a RS 232 communication connect a PC COM port to the instrument RS 232 terminal using the RS 232 serial communication cable a USB communication connect a PC USB port to the instrument USB connector using the USB interface cable Switch on the PC and the instrument Set the desired communication port RS 232 or USB Run the HVLink PRO PC software The instrument is prepared to download data to the PC Oooo Note a USB drivers should be installed on PC before using the USB interface Refer to USB installation instructions available on installation CD 34 MI 3250 MicroOhm 10A Maintenance 7 Maintenance Unauthorized persons are not allowed to open the MicroOhm 10A instrument There are no user replaceable components inside the instrument except the battery Warning a A Disconnect all measuring accessory mains supply and switch off the instrument before opening battery cover 7 1 Cleaning No special maintenance is required for the housing To clean the surface of the instrument use a soft cloth slightly moistened with soapy water or alcohol Then leave the instrument to dry totally before use Warnings a Do not use liqui
27. p E d t 4 E 4 AJ i t UA E ADC ADC ADC ADC t Figure 5 6 Continuous Mode Note a The Continuous Mode is especially helpful for troubleshooting 5 2 3 Automatic Mode Automatic mode makes a single bidirectional measurement The instrument will measure resistance in both directions thermal EMF elimination and started a single measurement every time the P1 P2 C1 and C2 are connected to the test object The main result displayed on the display is an average of the last bidirectional measurement R R_ WE D X The range and current output can be user defined before the test or automatically set To make another measurement simply break and remake contact with the test sample Automatic measurement I t plot Test A MEE Start Stop g uy P1 P2 C1 C2 OK P1 P2 C1 C2 OK P1 P2 C1 C2 OK p 1 1 l d l oi g s d t UA MN ADC ADC d ADC ADC gt t Figure 5 7 Automatic Mode Note a The Automatic Mode can be primarily used for measuring Bus bars 32 MI 3250 MicroOhm 10A Measurement Note about thermal EMF a A junction between two different metals produces a voltage related to a temperature difference thermocouple MicroOhm 10A eliminates the thermal EMF effect by measuring resistance in both directions I and 5 2 4 Inductive Mode
28. pack cell charger This means that the battery cells are connected in series during the charging The battery cells have to be equivalent same charge condition same type and age a One different battery cell can cause an improper charging and incorrect discharging during normal usage of the entire battery pack it results in heating of the battery pack significantly decreased operation time reversed polarity of defective cell a If no improvement is achieved after several charge discharge cycles then each battery cell should be checked by comparing battery voltages testing them in a cell charger etc It is very likely that only some of the battery cells are deteriorated The effects described above should not be confused with the normal decrease of battery capacity over time Battery also loses some capacity when it is repeatedly charged discharged Actual decreasing of capacity versus number of charging cycles depends on battery type This information is provided in the technical specification from battery manufacturer MI 3250 MicroOhm 10A Safety and operational considerations 2 3 Standards applied The MicroOhm 10A instrument is manufactured and tested in accordance with the following regulations Electromagnetic compatibility EMC EN 61326 Electrical equipment for measurement control and laboratory use EMC requirements Class A Safety LVD EN 61010 1 Safety requirements for electrical equipment
29. puts and battery compartment Legend 1 Measuring inputs outputs 2 Battery compartment Figure 3 5 Correct inserted batteries Warnings a When connected to an installation the instruments battery compartment can contain hazardous voltage inside a Disconnect all test leads remove the power supply cable and switch off the instrument before opening the battery compartment Ensure batteries are used and disposed of in accordance with Manufacturers guidelines and in accordance with Local and National Authority guidelines 14 MI 3250 MicroOhm 10A Instrument description 3 3 Accessories The accessories consist of standard and optional accessories Optional accessories can be delivered upon request See attached list for standard configuration and options or contact your distributor or see the METREL home page http www metrel si 960 Figure 3 6 Standard set of the instrument Instrument MI 3250 MicroOhm 10A Current test leads with crocodile clip 2 5 m 2 5 mm 2 pcs Kelvin Current test leads 2 5 m 2 5 mm 2 pcs Potencial test leads 2 5 m 1 5 2 pcs black Crocodile clips 4 pcs black red Test probes 2 pcs black Mains cable NiMH rechargeable batteries 3500mAh 6 pcs RS232 serial cable USB cable Bag for accessories PC SW HVLink PRO Instruction manual Calibration certificate DDLIODOCDIDDDOCOOCOLDULDIZ 15 MI 3250 MicroOhm 10A Inst
30. rted correctly otherwise the instrument will not operate and the batteries could be discharged If the instrument is not to be used for a long period of time remove all batteries from the battery compartment a Alkaline or rechargeable Ni Cd or Ni MH batteries can be used Metrel recommends only using rechargeable batteries with a capacity of 3500mAh or above a Do notrecharge alkaline battery cells MI 3250 MicroOhm 10A Safety and operational considerations 2 2 1 New battery cells or cells unused for a longer period Unpredictable chemical processes can occur during the charging of new battery cells or cells that have been left unused for a longer period more than 3 months Ni MH and Ni Cd cells can be subjected to these chemical effects sometimes called the memory effect As a result the instrument operation time can be significantly reduced during the initial charging discharging cycles of the batteries In this situation Metrel recommend the following procedure to improve the battery lifetime Procedure Notes gt Completely charge the battery At least 6h 3500mAh with in built charger This can be performed by using the gt Completely discharge the battery instrument normally until the instrument is fully discharged gt Repeat the charge discharge cycle at Four cycles are recommended in order to least 2 4 times restore the batteries to their normal capacity Notes a The charger in the instrument is a
31. rument description 3 4 Display organization 19 38 Of 1002 2 uo omer en eee 9 4 06 88 1 8 1 2 1 4 1 6 1 8 2 019 1001 600 1 10 7A R 1002 700 Mode Continuous Auto Range On 2 3 Measurement result window Measurement control window Messages window Battery and time indication AOIN Figure 3 7 Typical function display 3 4 1 Measurement result window Measurement window shows all relevant data during measurement campaign 21 19 _ 0 412 mo Eni B 2 18 12 14 16 18 0 28056 1 04A Ref 25 0 C R 0 391 0 Amb 40 0 C Figure 3 8 Measurement window Measured resistance is shown in the center of a screen with the largest font During measurement campaign this result is refreshed every few seconds After finishing measurement result is hold on screen until new measurement is started Bar graph graphically represents measured resistance in respect to the measurement range R shows resistance in the positive direction During measurement campaign this result is refreshed every few seconds After finishing measurement result is hold on screen until new measurement is started R shows resistance in the negative direction During measurement campaign this result is refreshed every few seconds After finishing measurement result is hold on screen until new measurement is started Ix shows current flow
32. wed voltage between test terminals and ground is 300 V The instrument comes supplied with rechargeable Ni Cd or Ni MH battery cells The cells should only be replaced with the same type as defined on the battery compartment label or as described in this manual Do not use standard alkaline battery cells while the power supply adapter is connected otherwise they may explode Hazardous voltages exist inside the instrument Disconnect all test leads remove the power supply cable and switch off the instrument before opening the battery compartment All normal safety precautions must be taken in order to avoid risk of electric shock while working on electrical installations MI 3250 MicroOhm 10A Safety and operational considerations A Warnings related to measurement functions Resistance and inductive measurement Q Q Q Q Q Resistance measurement should only be performed on de energized objects Do not touch the test object during the measurement or before it is fully discharged Risk of electric shock When a resistance measurement has been performed on an inductive object automatic discharge may not be done immediately High voltage can appear on test terminals when measuring inductive object Do not connect test terminals to external voltage higher than 300 V AC or DC in order not to damage the test instrument General Q Warning will appear on screen and the resistance test will not be performed if voltages
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