battery operated digital milli-ohmmeter
Contents
1. Altitude up to 2000 meter Relative humidity 8096 max Ambient temperature 0 C 40 C 3 4 5 14 SPARES amp ACCESSORIES At the date of printing this user s manual accessories were not yet available Please contact the factory for further information Spares are available from your nearest distributor LIMITED WARRANTY We warrant the product manufactured by us to be free from defective material or factory workmanship and agree to repair or replace this product which under normal use and service disclose the defect to be the fault of our manufacturing with no charge for parts and service If we are unable to repair or replace this product we will make a full refund of the purchase price Consult the user s manual for proper instruction regarding use of this instrument Our obligation under this warranty is limited to repairing replacing or making refund of this test equipment which proves to be defective within forty eight months from the date of original purchase This warranty does not apply to any of our products which have been repaired or altered by unauthorized persons in any way so as in our sole judgement to injure their stability or reliability or which have been subject to misuse abuse misapplication negligence or accident or which have had the serial numbers altered defaced or removed Accessories not of our manufacture used with this product are not covered by this warran2. OP RUSO Model TA137 BATTERY OPERATED DIGITAL MILLI DOHMMETER 0 0 2 Hz 1 ie 200 0m DIGITAL MILLIOHM METER INSTRUCTION MANUAL DESCRIPTION PAGE SAFE TY Sto 01 GENERAL 02 03 FRONT PANEL stes cc deb orem 04 PREPARATION FOR USE rere 05 PRELIMINARY CHECKS 05 PRECAUTIONS 06 MEASURING 07 SIMPLIFIED MEASUREMENT teoria 08 APPLICATIONS ru Sod 09 TEST LEADS c c 10 THERMAL 12 11 FUSES 12 INPUT LIMITS amp PROTECTIONS 13 SPECI FICATION Siissscrtecvesecasteresencsedicaicccecerstsicaeens 14 SPARES amp ACCESSORIES 15 LIMITED WARRANTY 15 CLEANING STORAGE crie etn onn 16 BATTERY amp FUSE REPLACEMENT 16 SAFETY RULES The meter has been designed with safety in mind However no design can completely protect against incorrect use Electrical circuits are dangerous and lethal through lack of caution or poor safety practice The following rules should reduce the danger Read the User s manual carefully and completely before using the instrument Fully understand the instructions before using this product Follow the instructions for every test Take a
3. located under the battery holder To replace fuse open the battery cover Then remove and replace the fuse located under the battery holder Only replace with same fuse specification 250mA 16 CAT IV Is for measurements performed at the source of the low voltage installation Is for measurements performed in the building Installation Is for measurements performed on circuits directly connected to the low voltage installation Is for measurements performed on circuits not directly connected to mains Due to our policy of constant improvement and development we reserve the right to change specifications without notice
4. Liquid Crystal Display Rotary Selector Switch Meet LVD amp EMC requirements 4 PREPARATION FOR USE When unpacked the tester should be inspected for any visible signs of damage and the preliminary checks described in the user s manual should be performed to ensure that it is operating correctly If there is any sign of damage or if the instrument does not operate correctly return it to your nearest supplier PRELIMINARY CHECKS Check the battery e f the battery symbol is shown the LCD then replace the batteries with new alkalines batteries before proceeding Check the current regulation Connect the current leads to and Select a range and short the current test leads The R led should go off indicating that the current regulation is ok Check the voltage measurement Connect the potential leads to P and Short the P and The display should indicate 0000 e Remove the short from P and P and C and Touching the potential test leads P to C and P to the R led should lit indicating an over voltage or over range This proving test can be repeated on all the ranges if need be You can also check the polarity indication of the milli voltmeter by touching the potential test leads P to C and P to C the R led should lit indicating an over voltage or over range The indicator should be indicating on the LCD showing the polarity change Total check can be
5. TEST presentative button is depressed for less than 2 seconds If the same push button is pressed for more than 3 seconds the test will carry on for 60 seconds The tester switch OFF completely when the rotary switch is in the OFF position The tester Hold the last reading before stopping the test The tester is fuse protected and has a crowbar between and This crowbar is activated by voltage If the voltage is too high that crowbar will blow the fuse automatically to interrupt the circuit The voltage between P and P is also protected for over voltage but does not have a fuse The tester has a temperature shut down The temperature sensing is done on the current regulation transistor Should this over temperature let lit allow the instrument to cool down for a while before proceeding further 3 FRONT PANEL LAYOUT If NO TEST LED lit the current source is stopped Over Temperature indicator Lit Over temperature 2305 Resistance between the current leads too high fuse 2398 Resistance between the potential leads too high Current Measurement Terminals Potential Measurement Terminals A 6 6 pouce pet d MICROPROCESSOR CONTROLLED AUTO HOLD Test Curren t an 1mA 10mA 10mA T MIN 100mA 100mA 20002 200 00 20 00 2000 0 200 0mo DIGITAL MILLIOHM METER OFF Current Range Table Start Stop Test
6. codile alligator clip for connection to the resistance to be measured The other end plugs into the meter 4mm shrouded color coded sockets SUPPLIED CURRENT TEST LEADS C test lead is of Green color shrouded 4mm safety plug which at one end have a crocodile alligator clip for connection to the resistance to be measured The other end plugs into the meter 4mm shrouded color coded sockets C test lead is of Black color shrouded 4mm safety plug which at one end have a crocodile alligator clip for connection to the resistance to be measured The other end plugs into the meter 4mm shrouded color coded sockets 10 THERMAL EFFECTS Temperature can have a significant effect on the performance of a digital milli ohmmeter due to the temperature coefficient of the resistance under test and thermal EMF s across the dissimilar conductors Most conductors have a large temperature coefficient of resistance For example 0 4 C for copper A copper conductor that has a resistance of 10 00m ohm at 20 C will increase to 10 40m ohm at 30 C This change should be taken into account when making measurements A current going through a resistance will also elevate its temperature So duration of the test can change the resistance When measuring the resistance of item such as current shunts which have joints of dissimilar conductors thermal EMF can affect the accuracy of the measurement This condition can be detected if the
7. done by shorting all the test leads together C P P The display should indicate close to 0000 depending of the crocodiles clips used and how they are shorted Both RC and LED should be OFF indicating that everything work ok 5 PRECAUTIONS Always ensure that the circuit to be measured is switched OFF isolated and completely de energised before connecting the test Leads e If it is probable that the instrument s protection has been impaired due to electrical mechanical or environmental damage it must not be used It should be returned to your nearest distributor or agent for checking and repair To prevent damage to the liquid crystal display the minimum storage temperature of 20 C must be observed It should also be noted that below 0 C the operation of the LCD will be sluggish If the exterior of the instrument requires cleaning it should be done with a sponge and a mild solution of detergent and water Other mechanical cleaning agents must not be used 6 MEASURING Perform the preliminary checks before proceeding with measurement and ensure that the precautions listed are observed Connect the test leads color coded to the instrument as shown The current test leads must always be outside of the potential test leads Please note that the shorter the potential test leads the better long potential test leads will pick up noise Screened test leads are recom
8. ests does not lit R this is indicative of this fuse being blown HBC 0 5A 250Vac Slow Blow 12 INPUT LIMITS amp PROTECTIONS The maximum continuous voltage which can be applied across the potential and current leads is around 10 7V Applying more than that voltage will automatically blow their respective fuses However the crowbar trigger can be factory adjusted for your application We have specially selected that method to stop damaging the instrument should it be misused 13 SPECIFICATIONS ELECTRICAL Measuring Ranges 0 200 0m ohms in steps of 100p ohm 0 2000m ohms in steps of 1m ohm 0 20 00 ohms in steps of 10m ohm 0 200 0 ohms in steps of 100m ohm 0 2000 ohms in steps of 1 ohm Accuracy 10 596 of reading 2 digits over the Operating temperature range 15 C to 55 C with the supplied test leads Test Current 1mA gt 2000 ohms range 10mA gt 200 20 ohms ranges 100mA gt 2000 200m ohm ranges Test Current Accuracy 0 1 Protection Fuses Supply 1 5A HBC 5 x 20mm DIN Current 1A HBC 5 x 20mm DIN Voltage 0 5A HBC 5 x 20mm DIN SAFETY LVD BS EN 61010 1 EMC BS 50081 1 BS EN 50082 1 MECHANICAL Case Height 110mm Case Width 250mm Case Depth 190mm Bump Test IEC68 2 29 Vibration Test IEC 1010 clause 8 3 Drop Test EC1010 clause 8 4 Impact Test IEC1010 Clause 8 2 Weight 1 542kg Rated environmental conditions 1 Indoor Use 2 Pollution Degree 2
9. ll the necessary precautions Do not exceed the limits of this instrument The circuit to be tested must be de energised and isolated before connections are made to it not use test leads probes or crocodiles aligators clips that are dirty damaged or have broken or cracked insulation Such accessories should be removed and repaired Immediately Always disconnect the test leads before replacing any fuse Always replace the fuse with the type specified and ensure that they are correctly fitted Double check the switch settings and leads connections before measuring Make a sketch to ensure proper operation and principle of measurement is correct and well understood e Do not touch any exposed wiring connections or other parts of an electrical circuit If in doubt check the circuit first for voltage before touching it e This instrument should only be used by a competent suitably trained person which understand fully this test amp measurement procedure Warning risk of electric shock Caution refer to this manual before using the Meter 1 GENERAL DESCRIPTION The meter digital milli ohmmeter is a battery operated instrument wich supply a low current to the circuit under test with which stable accurate measurement of low resistance can be made still over a wide range of values Resolution on the lowest range is 100 ohm and on the highest range 1 ohm The meter has 5 measuring range
10. mended for better environmental noise rejection Compression Joint MAX DC20V MICROPROCESSOR CONTROLLED AUTO HOLD Test Curren t a 1mA 10mA 10mA Lm 100mA 200 00 EH Ne 20 0005 2000 200 0mo DIGITAL MILLIOHM METER orr EnerSave_ o 7 SIMPLIFIED MEASUREMENT The 4 wires measurement has many advantages The errors due to the resistance of the test leads and the contacts as well as R and R are eliminated However in some cases for example when using the high resistance range 2000 ohms the four wires method is not necessary to still have a good percentage of accuracy compared to the full scale The simplified method of two wires can be used without too much problems C and P can be shorted as well as C and 25 DC20V MICROPROCESSOR CONTROLLED AUTO HOLD Test Current Range 20000 10 _ 200 08 10mA __ 20 008 930 100mA _ 2000 0 Hz z ae 100mA _ 200 IM 20000 DC KA 200 02 294 20 0005 2000 0 200 0mo DIGITAL MILLIOHM METER e ON 8 APPLICATIONS The meter Digital milli cohmmeter with its measuring range of 100 yohms to 2000 ohms is suitable for a wide range of applications such as Measuring the winding resistance of electric motors generators And transformers Bo
11. nd testing in mines aircraft railways ships domestic and industrial wiring installations Measuring the ring main continuity testing in industrial and domestic wiring installations Measuring resistance in electronic equipment such as shunts pcb tracks switch and relay resistance Checking compression joints on overheads lines Testing and maintenance of switchboard sub station equipment on such items as fuses joints contacts and bonds 9 TEST LEADS The test leads supplied with the instrument are suitable for connecting to conductors up to 17mm in diameter or bus bars 17mm tick There will be instances where the item being measured require larger jaws and the user is advised to make up his own leads There will be occasions when longer leads are required due to the geometry of the item being tested Some guidance notes should assit in the assembly of such leads Length of the potential leads should be as short as possible Insulated 16 0 2mm tinned copper wire is recommended The two potential leads should have the same length to minimise inaccuracies due to unbalance SUPPLIED POTENTIAL TEST LEADS lead is of Red color shrouded 4mm safety plug which at one end have a crocodile alligator clip for connection to the resistance to be measured The other end plugs into the meter 4mm shrouded color coded sockets test lead is of Blue color shrouded 4mm safety plug which at one end have a cro
12. reading alters when the leads are reversed To compensate for this effect the average of the two readings should be taken as the true measurement 11 FUSES REPLACEMENT There are three fuses Power Supply Fuse The power supply fuse is situated under the tester Open the battery compartment and replace the fuse with the same type 1 5A gt 24V Slow Blow Current Circuit Fuse Fuse protection is provided on the current terminals This fuse is situated under the Printed Circuit Board To access it you need to unscrew the four mounting screws which are holding the font panel Two os these screws are located under the foots and the two others are located inside the battery compartment The fuse is automatically blow by the crowbar should voltage be present on the resistance under test This is to prevent damage to the instrument It is indicative of this fuse being blown is the R Led stays on HBC 1A 250Vac Slow Blow Potential Circuit Fuse Fuse protection is provided on the potential terminals This fuse is situated under the Printed Circuit Board To access it you need to unscrew the four mounting screws which are holding the font panel Two os these screws are located under the foots and the two others are located inside the battery compartment The fuse is automatically blow by the crowbar should voltage be present on the resistance under test This is to prevent damage to the instrument If the preliminary t
13. s from 200 0milli ohm to 2000 ohms Measurements are displayed on a 375 digit custom liquid crystal display with large digits This instrument is powered from batteries only alkaline or rechargeable equivalent It has a regulated DC constant current source with current of 1mA 10mA and 100mA The instrument supply that current to the resistance being measured through the C and C terminals C being C being The voltage drop across the resistance under test is measured by the potential terminals P and P being P being Should the current regulation drops out R Led will lit indicating that the resistance in the current circuit is too high Lowering the current by selecting a higher resistance range can solve the regulation Should the R Led lit that mean that the voltage measured on the resistance is too high and therefore over range The resistance is measured precisely when the R and R Leds do not lit If anyone of these leds lit then the measurement can be inaccurate 2 The meter has a built in custom 372 digit liquid crystal display can be viewed in most lightning conditions This display indicates the diferentes conditions Hold m buzzer polarity condition of load or automatic decimal point change The ranges are selected by a 5 position rotary switch and a test is initiated by pressing the ON push button The instrument takes measurements for 10 seconds if the ON
14. ty All warranties implied by law are hereby limited to a period of forty eight months and the provisions of the warranty are expressly in lieu of any other warranties expressed or implied The purchaser agrees to assume all liability for any damages or bodily injury which may result from the use or misuse of the product by the purchaser or it s user his employees or others and the remedies provided for in this warranty are expressly in lieu of any other liability we may have including incidental or consequential damages We reserve the right to discontinue models at any time or change specification price or design without notice and without incurring any obligation 15 CLEANING amp STORAGE Periodically wipe the case with a damp cloth and detergent do not use abrasives or solvents If the meter is not to be used for periods of longer than 60 days remove the batteries and store them separately BATTERY amp FUSE REPLACEMENT Battery Replacement The tester continuously monitors the battery voltage and indicates when the batteries need to be replaced The tester s battery is situated under the tester Disconnect the test leads from the instrument and remove the battery cover and the batteries Replace with eight 1 5V AA pen light batteries taking care to observe correct polarity Alkaline batteries are recommended Replace battery holder and the battery cover Fuse Replacement The fuse is
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