AEMC Instruments AEMC 3711 Clamp-on Ground
Contents
1. sss 13 Function Controls ccecccesseceeesseeceeeseeeceeeseeeeeeeseneeeeeseeeeaeessensseesseeeaeess 14 jo 14 nore m eaaa 15 ab 15 Beeper DISable e eee ter iere e teneo e eur ex ERR eeu RRRRRSE 15 ReSISIATICG cies e EUER QUARE S RARUR ARE QN ERR URMA oananan dase cacederaadunmasaenenaaedd 15 HeSISIATICG oi aen HEU QRARESRARURIRE ARRRReRNRAR EARN AR ach cavnadcasadeunadenenee sade 16 ecu 17 Alari iranin T E E 18 Programming the Alarm Setpoint sss 18 Changing the Alarm Trigger ssssseeeeeenee 19 SHIRE TRES 19 MeMO CHE lane a eae 20 Memory Recall 5 21 1 Dicite rede rsaoc a eben eR ade 20 Clear Memoty ied uiences criteri rites t eth Fete d caede ara oe aide 20 Shop for AEMC products online at www S h opAE M C com 1 877 766 5412 Programming Summary sse 21 Principle of Operation sssessssssssesesesneeeen nennen nnns 22 Field Applications sesssesssssseee ener nnns 24 Pole Ground Ul 010 eee 24 Service Entrance or Meter ssssssssese nnns 25 Pad Mounted Transformer essen 25 Pad Mounted Transformer esses nnne 26 Transmission Towers ssssssseseeeeneeeeneenenennn nnn nnner ern2. value on the display 3 Display 3000 count LCD function indicators Shop for AEMC products online at www S h opAE M C com 1 877 766 5412 6 A Current measurement 7 Lever Opens or closes jaws 10 Ground Resistance Tester Models 3711 and 3731 Model 3731 Controls 1 Head Assembly Consists of two individually shielded magnetic cores 2 Hold Freezes last measured value on the display 3 Display 3000 count LCD function indicators 4 ON OFF Power ON or OFF activates display self test at power up 5 Q Resistance Measurement le Increment the Alarm setpoint SAM use increment Memory position in BBBBS program mode 588 amp 6 964 6 A Current Measurement lt 4 Decrement the Alarm setpoint decrement the Memory in program mode 7 AL Activates deactivates the Alarm function access the value of the Alarm setpoint in program mode 8 MEM Stores the reading into memory reads Memory Recall MR values and clears the memory in recall mode 9 Lever Opens or closes jaws Shop for AEMC products online at www S h opAE M C com 1 877 766 5412 siis Ground Resistance Tester Models 3711 and 3731 Digital Display Features NOISE mA A Q eil ET NOISE mC I CI CI ZI mA Hoo Q TED y D s D Ga mm 10 O a ICH mr KETE DIA Figure 3 Displayed when the beeper is active To turn the beeper On Off push ON amp Q together at power up T
3. 322mm Jaw Opening 1 38 35mm Operating Temperature 14 to 131 F 10 to 55 C Operating Humidity 10 to 90 RH 14 to 104 F 10 to 40 C 75 RH 131 F 55 C Storage Temperature 22 to 158 F 30 to 70 C Altitude Operational 2000m Storage 12000m Power Supply 9V Alkaline IEC 6LF22 or NEDA 1604A Battery Life Typical 8 hours or approx 1000 measurements of 30 s LCD 3 3 4 digit 1 73 x 1 10 44 x 28mm US Design Patent No 362 639 Safety Specifications ce E s EN 61010 1 Class 2 Double Insulation Working Voltage 150V Cat III Pollution Degree 2 300V Cat II Pollution Degree 2 Environmental P30 Protection Index EN 60529 Ed 92 IK04 EN 50102 Ed 95 Vibration Test IEC 68 2 6 Shock Test IEC 68 2 27 Drop Test 1m IEC 68 2 32 Max A Overload 100A continuous 200A 5s 50 60Hz OL displayed above 29 99Arms Electromagnetic Compatibility FN 61326 14A1 industrial anviranment Shop for AEMC products online at www S h opAE M C com 1 877 766 5412 EU Ground Resistance Tester Models 3711 and 3731 Model 3711 Controls AEMC Model 3711 GROUND TESTER ill EIE NOISE aG xin no mA LLCLLLUI Q ms amp e pbi Figure 1 1 Head Assembly Consists of 4 ON OFF Power ON or OFF two individually shielded activates display self test at magnetic cores power up 2 Hold Freezes last measured 5 Q Resistance measurement
4. 0 010 1 0 to 50 00 0 10 50 to 1000 0 50 100 to 2000 10 200 to 4000 50 400 to 6000 100 600 to 12000 500 aiias Upon initial power on the function is chosen by default AEMC Model 3711 GROUND TESTER The Models 3711 and 3731 will track down to 0 070 and indicate R lt 19 below 0 10 Fig 10 Accuracy is not defined below 0 10 Measurements below 0 10 typically or even 1Q indicate the ground tester is clamped onto a closed loop and that the signal is not flowing through the ground under test Figure 10 KB AEMC Model 3711 If the resistance readings are above 12000 OL GROUND TESTER will be displayed on the LCD Fig 11 This may indicate high ground resistance but may also be caused by a disconnected or poorly bonded ground Figure 11 Shop for AEMC products online at www S h opAE M C com 1 877 766 5412 16 Ground Resistance Tester Models 3711 and 3731 Current Press A to enter the current function True RMS current measurements are possible up to 30 00A Fig 12 Above 30Arms OL will be displayed and the test must be discontinued The beeper is also activated during OL Range Resolution 1 to 299mA 1mA 0 300 to 2 999A 0 001A 1mA 3 00A to 29 99A 0 01A 10mA AEMC Model 3711 INSTRUMENTS GROUND TESTER Figure 12 Shop for AEMC products online at www S h opAE M C com 1 877 766 5412 q
5. 1 Remove ground bar Pedesta connection to pedestal rod Cc gt 2 Extend pedestal rod lead to the ground bar using a temporary jumper Ground Bar Sheath Connection H Ground level Figure 30 Shop for AEMC products online at www S h opAE M C com 1 877 766 5412 30 Ground Resistance Tester Models 3711 and 3731 Above Telephone Space Select the current range A Clamp onto the ground wire and measure the current Fig 31 The maximum current range is 30A If the ground current exceeds 5A resistance measurements are not possible Do not proceed further with the measurement Remove the clamp on tester from the circuit noting the location for attention and continue to the next test location After noting the current select the ground resistance range Q and measure the resistance directly The reading you measure with the 3711 3731 indicates the bonding connections between the Telephone ground and the Power company ground One of the following two scenarios should be observed A lf OL or a high resistance Staples reading is displayed this a would indicate no bond has been established or a poor iz B connection exists between the Telephone and Power grounds yen Grou
6. 3711 and 3731 Description The Ground Resistance Tester Models 3711 and 3731 measure ground rod and small grid resistance through any season without the use of auxiliary ground rods Clamp on ground resistance testers are used in multi grounded systems without disconnecting the ground under test The Models 3711 and 3731 simply clamp around the ground conductor or rod and measure the resistance to ground By performing measurements on intact ground systems the user also verifies the quality of the grounding connections and bonds Resistance and continuity of grounding loops around pads and buildings may also be measured Both models include a current measurement function The probe s high sensitivity enables measurement of leakage current flowing to ground or circulating in ground loops down to 1mA and neutral currents to 30Arms This feature provides additional information which is becoming vital as distribution ground networks carry higher levels of noise and harmonics which affect power quality Both models offer battery life information at power up and Auto Off for power management Additional features are also displayed on the large LCD to ensure precise measurements The Buzzer and Auto Off features may be disabled from the push buttons at any time The Model 3731 offers an Alarm function and a Memory logging function In the Alarm mode the probe will audibly and visually indicate if the reading is beyond an input set point The
7. S h opAE M C com 1 877 766 5412 243 Ground Resistance Tester Models 3711 and 3731 Function Controls Model 3711 and 3731 share common functions On Off A Q Auto off Buzzer disable Hold Even though the Model 3711 is shown in the examples for these functions the controls will respond identically for the Model 3731 On Off The ON OFF push button when pushed actuates power on or power off with an audible control tone Upon initial power up the instrument will be in the Ohms function Q and will go to OL until clamped on When the ON push button is pushed and held down after three seconds the instrument will beep and provide a self test featuring a full function display Fig 4 followed by status indications for a Status of remaining battery life battery symbol blinks 0 100 Fig 5 b Number of stored values in memory MEM blinks 0 99 Model 3731 only Release the ON OFF push button to initialize the instrument B AEMC Model 3711 KB AEMC Model 3711 INSTRUMENTS GROUND TESTER INSTRUMENTS GROUND TESTER ei ST NOISE G R lt 19 ei TI NOISE m6 830 Ci Ch CIC mA Ci Ct CIC mA OOO Q Q m g Figure 4 Figure 5 Shop for AEMC products online at www S h opAE M C com 1 877 766 5412 4 Ground Resistance Tester Models 3711 and 3731 Auto Off The instrument will shut off automatically after five minutes of non use The instrument will issue a short beep 15 sec
8. from the system neutral or ground wire to the ground rod or rods as the circuit provides Select the current range A Clamp onto the ground conductor and measure the ground current The maximum range is 30 00A Trms However if the ground current exceeds 5A or noise exceeds 50V ground resistance measurements are not possible Do not proceed further with the measurement Remove the instrument from the circuit noting the location for maintenance and continue to the next test location After noting the ground current select the ground resistance range O and measure the resistance directly The reading you measure with the clamp on tester indicates not just the resistance of the rod but of the connection to the system neutral and all bonding connections between the neutral and the rod Note that in Fig 22 there is both a butt plate and a ground rod In this type of circuit it is necessary to place the instrument above the bond so that both grounds are included in the test For future reference note the date ohms reading current reading and pole number Replace any molding you may have removed from the conductor Grounding conductor Ground rod Ground level Butt plate Shop for AEMC products online at www S h opAE M C com 1 877 766 5412 24 Ground Resistance Tester Models 3711 and 3731 Note A high reading or OL indicates one or more of the following A Poor gr
9. nn nnns 27 Central Office Locations sssssssssseenn nnns 27 Service Panel ssssssssesssssseseseeneneenehnn nnne neh terns seta iren sd sedan 28 Phone Pedestal 0 0 cccccccccccecccccsceseeeeececeeseeeeaueeseeeeeseuaeaaeeeeeseeananees 29 Above Telephone Space sess 31 General Measurement Notes 0 0cccceceeeseseeeeeeeeeeeeeeeeeeeeeeeeeeeeeees 31 Operating Reference Card eee 32 Field Test EOOp i t sete esata dene a2 dade u An LL dU dnce 32 Commonly Asked Questions for 33 Clamp on Ground Resistance Measurements ssssuuss 33 MaintenariGe i aceti eee a bes ae ee Dea Popup ester ceu n ed Ei 34 Battery Replacement Procedure sse 35 Troubleshooting sess ener enne 35 Repair and Calibration isisisi inisini aniisi aaia aaa aaa aaia 36 Technical and Sales Assistance eese 36 Shop for AEMC products online at www S h opAE M C com 1 877 766 5412 Ground Resistance Tester Models 3711 and 3731 A Warning A These safety warnings are provided to ensure the safety of personnel and proper operation of the instrument e The instrument must not be operated beyond its specified operating range Safety is the responsibility of the operator All metal objects or wires connected to the electrical system should be assumed to be lethal until tested Grounding systems are no exception
10. the owner for a period of one year from the date of original purchase against defects in manufacture This limited warranty is given by AEMC Instruments not by the distributor from whom it was purchased This warranty is void if the unit has been tampered with abused or if the defect is related to service not performed by AEMC Instruments For full and detailed warranty coverage please read the Warranty Coverage Information which is attached to the Warranty Registration Card if enclosed or is available at www aemc com Please keep the Warranty Coverage Information with your records What AEMC Instruments will do If a malfunction occurs within the one year period you may return the instrument to us for repair provided we have your warranty registration information on file or a proof of purchase AEMC Instruments will at its option repair or replace the faulty material YOU CAN NOW REGISTER ONLINE AT www aemc com Warranty Repairs What you must do to return an Instrument for Warranty Repair First request a Customer Service Authorization Number CSA by phone or by fax from our Service Department see address below then return the instrument along with the signed CSA Form Please write the CSA on the outside of the shipping container Return the instrument postage or shipment pre paid to Chauvin Arnoux Inc d b a AEMC Instruments 15 Faraday Drive Dover NH 03820 USA Tel 800 945 2362 Ex
11. the reference Additionally if the tested rod is poorly bonded to the ground connector a high reading will be present Q Does this mean I am not able to test an independent electrode A No however as soon as the connection is made to a multiple electrode system usually provided by the connection to the system neutral you can clamp on and make a measurement Q Must the instrument be clamped directly on the electrode A No the instrument will provide valid measurement results when clamped on to the electrode or the conductor leading to the grounding electrode The reading through the conductor will also verify not only the grounding electrode resistance but connections of the ground wire to the rest of the system Q Does the system under test have to be energized or de energized to perform the test A We are measuring the grounding network The only requirements are that ground connections be made to the system under test and that the voltage to ground at the tested point not exceed the instrument rating Shop for AEMC products online at www S h opAE M C com 1 877 766 5412 233 Ground Resistance Tester Models 3711 and 3731 Q Can the clamp on method be used for substation grid resistance testing A It depends It can be used as long as the instrument can be clamped onto a point on the grounding system at a common point where it ties to the system neutral Testing a grid must be treated as if it were a single elect
12. to 12000 100 to 2000 10 3 0 R 19 200 to 4000 50 6 096 R 50 400 to 6000 100 10 R 100 600 to 12000 500 Approx 25 500 Ground or Leakage Current Measurement Range Range Resolution Accuracy 1 to 299mA 1mA 2 5 R 2mA ee 0 300A to 2 999A 0 001A 2 5 R 2mA imAto30 00Arms O 900A to 2 999A 0 001A 25 R 2mA 3 00A to 29 99A 0 01A 2 596 R 20mA R Reading Reference conditions 23 C 3K 50 RH 10 battery at 8V 0 2V external magnetic field lt 40A m external electrical field lt 1V m conductor centered loop resistance noninductive Accuracy of Reading Frequency 50 60Hz Resistance Measurement Frequency 2403Hz Voltage Generated into the Loop Approx 60mVrms Alarm Range Model 3731 Only 0 to 1990 Resistance Overload OL displayed above 12000 Current Measurement Frequency 47 to 800Hz Influence of Frequency Add 7 5 to the reference specification Current Overload OL displayed above 29 99Arms Mechanical Specifications Dimensions 9 25 x 3 94 x 2 17 235 x 100 x 55mm Shop for AEMC products online at www S h opAE M C com 1 877 766 5412 8 Ground Resistance Tester Models 3711 and 3731 Case Material Lexan 920A UL94V2 or equivalent Jaw Cover Material Lexan with 1096 fiberglass charge UL94VO or equivalent LCD Cover Material Clear Lexan UL94V1 or equivalent Color Gray body red jaws Jaw Window Diameter 1 25
13. Clamp On Ground Resistance Tester Models 3711 and 3731 USER MANUAL P AEMn Shop for AEMC products online at wwwSShopAEMC com 1 877 766 5412 XC a EARP EDAR e d ee ee NESSE EE E COS CICS CCS E E E CIID ODO Y Statement of Compliance Chauvin Arnoux Inc d b a AEMC Instruments certifies that this instrument has been calibrated using standards and instruments traceable to international standards We guarantee that at the time of shipping your instrument has met its published specifications An NIST traceable certificate may be requested at the time of purchase or obtained by returning the instrument to our repair and calibration facility for a nominal charge The recommended calibration interval for this instrument is 12 months and begins on the date of receipt by the customer For recalibration please use our calibration services Refer to our repair and calibration section at www aemc com Serial Catalog 2117 60 2117 61 Model 3711 3731 Please fill in the appropriate date as indicated Date Received Date Calibration Due Chauvin Arnoux Inc B d b a AEMC Instruments INSTRUMENTS www aemc com eS e pe ee E E EE S Se ee os CS RS S EL rer p Shop for AEMC products online at www S h opAE M C com 1 877 766 5412 Limited Warranty The Models 3711 and 3731 are warranted to
14. Freeze hold the display MEM ON Short beep On Off memory recall MR Q ON Toggle the buzzer on off MEM ON Long beep 6s Clear memory CLR HOLD ON Toggle auto power on off A ON Toggle memory display on off Figure 32 Field Test Loop The test loop of 25Q Fig 33 is provided to perform a quick check of the instrument Check the clamp on ground resistance tester by clamping around the loop the 3711 or 3731 should read between 24 20 and 25 80 Value is for ambient temperature between 68 and 78 F Value may differ a few counts under or above this temperature O O V J AEMC LO CALIBRATION LOOP 250 O J Shop for AEMC products online at www S h opAE M C com 1 877 766 5412 3 327 Ground Resistance Tester Models 3711 and 3731 Commonly Asked Questions for Clamp on Ground Resistance Measurements Q Can the Clamp on method be used effectively on high tension towers despite the distance or spacing between them A Yes Extended distances will not adversely affect the measurement results The important factor is that it be a multiple electrode system Q Does the grounding electrode have to be disconnected and isolated as is required when using the Fall Of Potential test with auxiliary electrodes A No Actually the electrode must be connected to the system to provide the path for test signal injection as well as to provide the background impedance necessary as
15. Use extreme caution when using the instrument around energized electrical equipment Never attempt to use the instrument to twist or pry the ground electrode or ground wire away from the equipment being grounded Open and close the clamp on jaws slowly ensuring proper alignment AEMC Instruments considers the use of rubber gloves to be an excellent safety practice even if the equipment is properly operated and correctly grounded International Electrical Symbols This symbol signifies that the instrument is protected by double or reinforced insulation Use only specified replacement parts when servicing the instrument This symbol signifies CAUTION and requests that the user refer to the user manual before using the instrument Risk of electric shock The voltage at the parts marked with this symbol may be dangerous This is a type A current sensor This symbol signifies that application around and removal from HAZARDOUS LIVE conductors is permitted E BEI Shop for AEMC products online at www S h opAE M C com 1 877 766 5412 4 Ground Resistance Tester Models 3711 and 3731 Definition of Measurement Categories CATI For measurements on circuits not directly connected to the AC supply wall outlet such as protected secondaries signal level and limited energy circuits CAT Il For measurements performed on circuits directly connected to the electrical distribution system Examples are measurements on household
16. appliances or portable tools CAT Ill For measurements performed in the building installation at the distribution level such as on hardwired equipment in fixed installation and circuit breakers CAT IV For measurements performed at the primary electrical supply 1000V such as on primary overcurrent protection devices ripple control units or meters Receiving Your Shipment Upon receiving your shipment be sure that the contents are consistent with the packing list Notify your distributor of any missing items If the equipment appears to be damaged file a claim immediately with the carrier and notify your distributor at once giving a detailed description of any damage Save the damaged packing container to substantiate your claim Packaging The Model 3711 Cat 42117 60 and Model 3731 Cat 2117 61 are shipped with a hard carrying case one 9V battery not installed a user manual with warranty registration and a field test loop The manual warranty card and test loop are located behind the egg crate foam on the inside of the carrying case cover Accessories Multiple Calibration Loop eeeee Cat 42135 46 Important Information Proper Operation The proper operation and measurement accuracv depends on the proper Shop for AEMC products online at www S h opAE M C com 1 877 766 5412 Suriaces dre Cl all aria utat MO IOTEIQTI Maller ODSUUCIS UTEIT CIOSITFIQ ET Ground Resistance Tester Models
17. d rod Often more than one ground conductor is tied to this clamp looping back to the enclosure or neutral Enclosure Open Door Open Door Service Bowe SS lc eS J N Eoncentrie Neutral Underground service Ground rod s Figure 25 In many cases the best reading can be obtained by clamping the instrument onto the ground rod itself below the point when the ground conductors are attached to the rod so that you are measuring the ground circuit Care must be taken to find the conductor with only one return path to the neutral Generally lt 0 70 indicates that you are on a closed loop In Fig 26 the ground rod is located outside the enclosure Clamp at the indicated measuring point to obtain the correct reading If more than one rod exists at different corners of the enclosure it is necessary to determine how they are connected to properly measure the ground resistance Enclosure feces SZ Ground rods j I Underground service Fiaure 26 Shop for AEMC products online at www S h opAE M C com 1 877 766 5412 26 Ground Resistance Tester Models 3711 and 3731 Transmission Towers Observe all safety requirements Dangerously high voltage may be present Locate the ground conductor at the base of the tower Many different configurations exist Care should be taken when searching for the ground conductor Fig 27 shows a single leg mounted on a concrete pad wit
18. e mail our technical support hotline Chauvin Arnoux Inc d b a AEMC Instruments 200 Foxborough Boulevard Foxborough MA 02035 USA Phone 800 343 1391 508 698 2115 Fax 508 698 2118 techsupport aemc com www aemc com Shop for AEMC products online at www S h opAE M C com 1 877 766 5412 36 Shop for AEMC products online at www S h opAE M C com 1 877 766 5412 E AEMC INSTRUMENTS Chauvin Arnoux Inc d b a AEMC Instruments 15 Faraday Drive Dover NH 03820 USA www aemc com Shop for AEMC products online at www S h opAE M C com 1 877 766 5412
19. eplacement Procedure The Clamp On Ground Resistance Testers are powered by a single 9V battery The battery replacement indicator will display continuously when battery replacement is required Recommended replacement type is Alkaline IEC 6LF22 6LR61 or NEDA 1604A Ni Cad batteries may also be used To change the battery refer to Figure 15 page 18 and follow this procedure 1 2 T The instrument must be OFF and disconnected from any conductor Place the meter face down and remove the two Phillips screws on the back of the instrument Remove back cover by pulling it down and away from the instrument Lift the battery away from the case and disconnect the battery Connect the new battery and position the leads so that they won t get pinched when the cover is replaced Replace the back cover noting that it slips beneath the hold down lip and fits securely into position Install and tighten screws Typical battery life is approximately 8 hours of use or about 1000 separate 30 second measurements Troubleshooting Symptom Indication Recommended Action Instrument will not turn ON Low Battery Replacement required Continuous audible tone Alarm setpoint tripped Deactivate Alarm or Change Setpoint Trigger mode Display is erratic Foreign matter in jaws Clean jaw mating surfaces Function controls inoperative Hold button on Turn HOLD off L iaht nulsina audible been Normal oneration Shop for AEMC products online a
20. from the sheath bond s or ground bar to the ground rod s as the circuit provides Select the current range A Clamp onto the ground conductor and measure the ground current The maximum current range is 30A If the ground current exceeds 5A ground resistance measurements are not possible Do not proceed further with the measurement Remove the clamp on tester from the circuit noting the location for maintenance and continue to the next test location After noting the ground current select the ground resistance range Q and measure the resistance directly The reading you measure with the 3711 3731 indicates the resistance of not just the rod but also the connection to the sheath ground and all bonding connections between the sheath bond and the rod A high reading indicates one or more of the following A Poor ground rod B Open ground conductor C High resistance bonds on the rod or splices on the conductor Also look for bad connections on the ground bar to the sheath s Note This same test can be done using the TIP instead of the sheath ground However keep in mind that this is intended to be grounded only back at the central office Shop for AEMC products online at www S h opAE M C com 1 877 766 5412 29 Ground Resistance Tester Models 3711 and 3731 Phone Pedestal Ground Bar Sheath Connection He Ground level Figure 29 Phone
21. g memory is now full Figure 16 Measurements may still be made but no longer logged Stored values are retained when the instrument is turned off Pressing the A and ON buttons again at power up will de activate the Memory feature Memory Recall To recall memory values push ON and KB AEMC Model 3731 MEM together at power up MR will be displayed with the memory number Fig 17 Memorized value will be displayed To select stored values use the cursor arrows down gt up For rapid access of memory recall values press the cursor push button continuously Turn the instrument off to exit the Memory Recall mode Figure 17 Clear Memory To clear the memory push ON amp MEM together at power up and hold them down After a three second interval the clear message will be displayed Fig 18 along with four repetitive beeps and a fifth long tone The memory is now cleared Fig 19 COnco cleared releacina the ON amp MEM hitttane retiirne the inetriimant ta Shop for AEMC products online at www S h opAE M C com 1 877 766 5412 20 Ground Resistance Tester Models 3711 and 3731 Model 3731 Model 3731 GROUND TESTER GROUND TESTER Figure 18 Figure 19 Function Access Summary Function Push Button s Function Setting Used Saved 9 Power Down On Off ON OFF Q Function Q Default Setting A Function A No Alarm Function Q AL Yes Displa
22. ge opening accommodates not only ground rods but larger ground conductors up to 1000 kcmil typically found in telecommunication or railroad applications The inner jaw is composed of two independent and individually shielded magnetic cores permitting the injection of a test signal and accurate return signal measurement without noise interference or cross talk common to separate probe instruments Thorough mechanical design including small winglets ensures repetitive jaw alignment for accuracy and prevents undesirable insertions into the jaw spring assembly Body Design The ergonomic body design permits one handed operation The guard provides additional strength and prevents the hand from slipping or coming into contact with conductors under test The Lexan or equivalent polycarbonate body construction provides strength The LCD lens cover may be easily replaced if scratched The sealed push buttons directly access all test functions and are easily operated even with gloved hands Lexan is a registered trademark of General Electric Corporation Shop for AEMC products online at www S h opAE M C com 1 877 766 5412 Des ee Ground Resistance Tester Models 3711 and 3731 Electrical Specifications Ground Resistance Measurement Range Range Resolution Accuracy 0 1 to 1 000 0 010 2 R 0 02Q 1 0 to 50 02 0 10 1 596 R 0 10 Auiorangine 50 0 to 100 00 0 50 2 0 R 0 50 0 019
23. h an external ground conductor The point at which you clamp the instrument should be above all splices and connections which allow for multiple rods butt wraps or butt plates Note Current flowing to ground may be high eNO Support a Concrete X Pad Ground Rod Figure 27 Central Office Locations The main ground conductor from a ground window or a ground plane is usually the location to clamp the tester Due to the wiring practices within the central office there are many locations at which you can look at the water pipe or counterpoise from within the building An effective location is usually at the ground buss in the power room or near the backup generator By measuring current and resistance at several points and comparing the readings you will be able to identify neutral loops utility grounds and central office grounas The test is effective ane accurate when the AraAiind vwrindaiar ia annnantard ta tha citilithe avarind anh ann aint Shop for AEMC products online at WWW ShopAEMC com 1 877 766 5412 227 Ground Resistance Tester Models 3711 and 3731 Service Panel If we clamp on the grounding electrode conductor in Fig 28 the multi grounded system required to complete the circuit may be from different sources These sources may include the following Electric Neutral Phone CATV and Water The Electric Utility Neutral should be the pr
24. he beeper is active when displayed Displayed when the HOLD function is activated This function locks the present displayed value During HOLD A Q and Alarm functions are deactivated The Memory function may still be used Indicates that the jaws of the instrument are not properly closed The Open Jaw indication is present only in the Q Mode Check for foreign matter in the jaw mating surface In the Q function this symbol indicates the presence of excessive stray noise in the ground electrode under test This symbol will be present if noise signals reach an amplitude of approx 5A or 50V Resistance measurement values are no longer valid The beeper is also activated Displayed when measured resistance is below 0 19 This may indicate that grounding electrode you are clamped onto is continuous with itself the instrument is measuring a metallic loop and not the ground electrode resistance In this situation electrode resistance measurements may not be valid The main display can measure between 0 7 to 0 070 but without any specified accuracy Current measurement mode Ground resistance measurement mode Shop for AEMC products online at www S h opAE M C com 1 877 766 5412 12 Ground Resistance Tester Models 3711 and 3731 Indicates the Auto Off feature is deactivated and the instrument e stays on permanently until turned off by the user With no symbol displayed after 5 minutes of non use the instrument will au
25. inciple conductor of the low impedance signal return path required to test the resistance of this ground electrode with the Model 3711 3731 This can be verified by removing other ground connections noting if any changes appear in the readings If by removing one of these signal return paths a much higher reading is noted it could mean that the primary signal return path the Electric Neutral is defective or open Warning For safety reasons do not remove any ground source without first de energizing the service panel ELECTRIC UTILITY A B NEUTRAL AAA e lt o 240 VAC CATV NEUTRAL BUSS ojojojojojojojojojo ojojo 0 0 0 0 0 i 9 o 9 GROUND BUSS Jj EI i e WH e BK T 120 VAC Bare SERVICE PANEL GROUND ELECTRODE Figure 28 Shop for AEMC products online at www S h opAE M C com 1 877 766 5412 28 Ground Resistance Tester Models 3711 and 3731 Phone Pedestal Provide sufficient room for the Model 3711 3731 jaws which must be able to close easily around the conductor Fig 29 The jaws can be placed around the ground rod itself Note If not enough room is available for this task refer to Fig 30 and continue with this example The clamp must be placed so that the jaws are in an electrical path
26. nd wire doubled B If and or a very low under ground clamp reading is displayed then the bond between these two grounds has been verified Figure 31 General Measurement Notes A reading of OL is most likely a cable which is not connected to the ground at both ends It may be there is no ground rod at all or that there is no path back to the system neutral A reading which is 0 10 generally indicates that the cable where you are clamped is continuous with itself You may have located a ground loop which can usually be confirmed by comparatively high current readings also obtained when readings are taken at multiple locations A good low resistance ground may also have very high AC current flowing depending upon the type of equipment being grounded Shop for AEMC products online at www S h opAE M C com 1 877 766 5412 23 2 Ground Resistance Tester Models 3711 and 3731 Operating Reference Card Included with the Model 3711 and 3731 you will find an operating reference card like the one shown here This card summarizes all the features of the Model 3711 and 3731 AEMC Clamp On Ground Resistance Tester cal INSTRUMENTS Operating Reference Model 3711 3731 Common Features Model 3731 Additional Features ON OFF On Off AL Turn alarm AL on off Q Measure ground resistance Q MEM Store the reading in memory A Measure AC current mA A AL ON Program alarm mode i Use lt gt to adjust lt Down Up gt HOLD
27. onds and the LCD flashes once per second The prior to shutting down Auto Off may be disabled by turning on the meter while holding down the HOLD push button The indicator will appear on the display to indicate the Auto Off feature has been disabled Fig 6 AEMC Model 3711 GROUND TESTER Hold The HOLD push button freezes the last measured value onto the display When the HOLD function is enabled is displayed on the LCD Fig 7 Figure 6 When the HOLD function is enabled other control function M functions are disabled except the memory To exit HOLD press the HOLD push button and normal operation is resumed Note When HOLD is pressed during power up Figure 7 the auto off feature is disabled and 99 is displayed on the LCD See Auto Off Beeper Disable To disable the beeper press the ON and Q together at power up The MJ indicator will disappear from the LCD Fig 8 AEMC Model 3711 GROUND TESTER This setting is saved indefinitely To reset the beeper press the ON and Q together at power up Shop for AEMC products online at www S h 0 pA E M C com 15 Fintira R 1 877 766 5412 Ground Resistance Tester Models 3711 and 3731 Resistance The Q function provides resistance measurements from 0 1 to 12000 in seven autoranges Fig 9 Range Resolution KB AEME Ss cc 0 07 to 10
28. ound rod B Open ground conductor C High resistance bonds on the rod or splices on the conductor watch for buried split butts clamps and hammer on connections Service Entrance or Meter Follow the same procedure as for Pole Ground Rods Notice that Fig 24 shows multiple ground rods and in Fig 23 the ground rods have been Ground level j Building wall gt Pole mounted transformer Service meter g mcn S Service box Figure 24 Ground rods p Pole mounted transformer Building wall gt replaced with a water pipe ground You may also have both types acting as a ground In these cases it is necessary to make the measurements between the service neutral and both grounded points Figure 23 Service box Service meter D A a KO d Shop for AEMC products online at www S h opAE M C com 1 877 766 5412 25 Ground Resistance Tester Models 3711 and 3731 Pad Mounted Transformer A Observe all safety requirements High voltage may be present Locate and number all rods usually only a single rod is present If the ground rods are inside the enclosure refer to Fig 25 and if they are outside the enclosure refer to Fig 26 If a single rod is found within the enclosure the measurement should be taken on the conductor just before the bond on the groun
29. rigger above or below a setpoint Follow the procedure below for setting the alarm trigger 1 The instrument must be OFF and disconnected from any conductor 2 Place the meter face down and remove the two phillips screws on the back of the instrument 3 Remove the back cover by pulling down and away from the instrument 4 To set the alarm to trigger above a setpoint slide the alarm setpoint switch 1 up To set the alarm to trigger below a setpoint slide the alarm setpoint switch 1 down 5 Replace the back cover while ensuring that it slips beneath the hold down lip and fits securely into position Use caution not to pinch the battery leads 6 Install and tighten screws Alarm Setpoint Switch Switch 1 Up Alarm above the setpoint Switch 1 Down Alarm below the setpoint Finiire 15 Shop for AEMC products online at www S h opAE M C com 1 877 766 5412 19 Ground Resistance Tester Models 3711 and 3731 Memory To activate the Memory feature press the A and ON buttons together at power up Fig C Model 3731 GROUND TESTER 16 MEM will be displayed The Memory feature allows the user to log into memory 1 to 99 measured values including OL Measured values can now be logged for both resistance Q and amps A by pushing the MEM button during measurement and during HOLD A long beep indicates the measurement was stored After the 99th value is entered MEM 99 will blink indicatin
30. rode Often clamping on to points within the grid system will yield a closed loop reading Q How does clamp on ground testing compare with the standard Fall Of Potential test A Empirical testing has validated that when performed correctly both methods will provide accurate and repeatable readings for ground electrode resistance Q How large a conductor can the jaw accommodate A The inner diameter of the jaw is 1 25 and can accommodate cables up to 1000 kcmil Maintenance A Warning e To ensure optimum performance it is important to keep the probe jaw mating surfaces clean at all times Failure to do so may result in error in readings To clean the probe jaws use a lint free clean cloth or if the jaws are pitted use a very fine sand paper fine 600 grit to avoid scratching the jaw then gently clean with a soft cloth Do not leave any residue e For maintenance use only specified factory replacement parts Avoid electrical shock do not attempt to perform any servicing unless you are qualified to do so Avoid electrical shock and or damage to the instrument do not allow water or other foreign substances into the case Disconnect the unit from all circuits and test cables before opening the case Use caution with metallic tools that may short battery packs power supplies etc Shop for AEMC products online at www S h opAE M C com 1 877 766 5412 34 Ground Resistance Tester Models 3711 and 3731 Battery R
31. s Ground Resistance Tester Models 3711 and 3731 Alarm Turn the Alarm on off by pressing the AL button The alarm feature provides a continuous audible warning when beeper is active and visual indications when a setpoint has been reached Fig 13 14 e g alarm indication when ground electrode resistance is above the NEC limit of 250 If the alarm is not triggered only will be displayed indicating that the alarm is active B AEMC Mode 3731 GROUND TESTER Figure 13 Programming the Alarm Setpoint To program the alarm setpoint push ON and AL together at power up The alarm setpoint value will blink To program the proper setpoint value 1 to 1990 use the cursor arrows a down up When the setpoint is reached turn the instrument off This will put the setpoint into GROUND TESTER memory Turn the instrument back on you may need to press AL to activate the alarm feature C Model 3731 Note The alarm setpoint is preset at 250 The alarm will be triggered when the setpoint is exceeded The user has the option of having the alarm triggered when a reading is below the programmed setpoint This is accomplished Figure 14 with an internal switch and outlined in the following section Shop for AEMC products online at www S h opAE M C com 1 877 766 5412 18 Ground Resistance Tester Models 3711 and 3731 Changing the Alarm Trigger The Model 3731 alarm may be set to t
32. t 360 603 749 6434 Ext 360 Fax 603 742 2346 or 603 749 6309 repair aemc com Caution To protect yourself against in transit loss we recommend you insure your returned material NOTE All customers must obtain a CSA before returning any instrument Shop for AEMC products online at www S h opAE M C com 1 877 766 5412 Table of Contents LA FEAST sta sE E 4 International Electrical Symbols sse 4 Definition of Measurement Categories sssssseseeeeee 5 Receiving Your Shipment sse 5 Packagirig te eti ted edat ed erdt au qe idt otv Rao UHR 5 ACOS SONOS 5 Important Information Proper Operation sese 5 BI fegienojo T eae 6 Product Construction ssssssssssseseeenenneneen rennes 6 SEUUDITIp E ES 7 sepa ine 7 Electrical Specifications ssssssseseeeneeene 8 Ground ResiStanGe iisiecues e dnas doe epa a tigna aa eR n n a aan YER ARREA NNER 8 Ground or Leakage Current sse 8 Mechanical Specifications 8 Safety Specifications ssssssssssssssseseeeeene nennen 9 Model 3711 Controls eesssssssssesseeeeenen enne 10 Model 3731 Controls ERE 11 Digital Display Features sese 12 Additional Features of the Model 3731
33. t www S h opAE M C com 1 877 766 5412 35 Ground Resistance Tester Models 3711 and 3731 m s Repair and Calibration To ensure that your instrument meets factory specifications we recommend that it be submitted to our factory Service Center at one year intervals for recalibration or as required by other standards or internal procedures For instrument repair and calibration You must contact our Service Center for a Customer Service Authorization number CSA This will ensure that when your instrument arrives it will be tracked and processed promptly Please write the CSA on the outside of the shipping container If the instrument is returned for calibration we need to know if you want a standard calibration or a calibration traceable to N I S T includes calibration certificate plus recorded calibration data Chauvin Arnoux Inc d b a AEMC Instruments 15 Faraday Drive Dover NH 03820 USA Tel 800 945 2362 Ext 360 603 749 6434 Ext 360 Fax 603 742 2346 or 603 749 6309 repair aemc com Or contact your authorized distributor Costs for repair standard calibration and calibration traceable to N I S T are available NOTE All customers must obtain a CSA before returning any instrument ss Technical and Sales Assistance If you are experiencing any technical problems or require any assistance with the proper operation or application of your instrument please call mail fax or
34. that particular rod in series with the equivalent parallel resistance value that the rest of the multi grounded system represents If we had an electrical system that had 101 grounding electrodes and each had a resistance value of 250 and we were to clamp around any electrode in the system the measured value would be 250 in series with the equivalent parallel resistance or 0 250 The displayed value would be 25 20 instrument resolution to 0 19 V I 250 0 250 Rx 25 20 In most field applications the number of electrodes that make up a multi grounded system would be higher therefore the equivalent parallel resistance is negligible with respect to the rod under test Shop for AEMC products online at www S h opAE M C com 1 877 766 5412 22 Ground Resistance Tester Models 3711 and 3731 Figure 20 Nh 2 2 WM M UP L aly my m rivl prd par pt Rx Figure 21 Shop for AEMC products online at www S h opAE M C com 1 877 766 5412 23 Ground Resistance Tester Models 3711 and 3731 Field Applications Pole Ground Rods Remove any molding covering the ground conductor and provide sufficient room for the jaws of the clamp on The jaws must be able to close easily around the conductor The jaws can be placed around the ground rod itself Note The instrument must be placed so that the jaws close around an electrical path
35. tomatically shut itself off The Auto Off feature is turned On Off by pressing Hold at power up Display flashes this symbol 1 second during a low battery condition Measurements are still possible When this symbol is displayed continuously measurements are no longer possible Battery replacement is necessary Indicates the approximate percentage of useful battery life 0 remaining 0 100 This function is displayed only upon initial power up when the ON push button is held down for more than 2 seconds mt The overload symbol will illuminate when the measurement LL reading is beyond the limits of the instrument Resistance 12000 Current 30 00A rms The beeper is activated in current overload Additional Features of the Model 3731 Indicates that an alarm set point is set in memory Alarm set Jo points may be set from 1 to 1990 Arrows indicate whether the measured value is above or below alarm setpoint 3 cs m Memory function is activated Ninety nine 99 separate values j may be logged for either resistance Q current A or a 77 combination thereof At the 99th value display number will blink indicating that memory is full mG Memory recall register Displays the numbered value being 77 recalled from memory 1 99 Note Models 3711 and 3731 share the same LCD and display all segments at power up Functions not available on the 3711 are displayed at power up Shop for AEMC products online at www
36. user may also have the Alarm initiated above or below the set point This Alarm feature permits quick field checks where only pass or fail readings will suffice The Memory function logs up to 99 measurements Ohms or Amperes This enables the user to conduct field surveys and to retrieve and analyze the readings at a later time The alarm settings and stored memory information are saved when the ground tester is turned off Product Construction The Models 3711 and 3731 body cases are built of Lexan for rugged use The probe heads are encapsulated in a double walled Lexan shell or equivalent polycarbonate for extra strength and are reinforced at the body interfaces for enhanced field reliability Overall construction and mechanical design ratings such as drop test shock and vibration weatherproofing against water projections meet or exceed IEC International Electrotechnical Commission standards The products havin alan hanan Anaiannnd ta mant DNI C4n4n Shop for AEMC products online at www S h opAE M C com 1 877 766 5412 6 Ground Resistance Tester Models 3711 and 3731 Jaw Design The probe head or jaw is a key component in the measurement and overall product performance Considerable research and development were dedicated to ensuring its performance reliability and versatility The large jaw has an inner opening diameter of 1 25 32mm permitting use on tight ground conductors on poles and in manholes The lar
37. y Hold HOLD No Auto Off On Off ON HOLD No Beeper On Off ON Q No 3711 Yes 3731 Programming Summary Function Push Buttons Function Setting Used Saved Power Down Memory On Off ON A Yes Memory Recall MR ON MEM lt 2 sec No Clear Memory ON MEM gt 6 sec No Program Alarm Setpoint ON AL No Shop for AEMC products online at www S h opAE M C com 1 877 766 5412 21 Ground Resistance Tester Models 3711 and 3731 Principle of Operation Typically grounded distribution system may be simulated by the basic circuit shown in Fig 20 or an equivalent circuit shown in Fig 21 If voltage V is applied to any measured grounding electrode Rx through a special transformer current I flows through the circuit thereby establishing the following equation 1 y Rx where usually Rx n 1 n 1 2 Ri be Ri Therefore V I Rx is established If is detected and measured with V kept constant the measured grounding electrode resistance Rx can be obtained A signal is fed to a special transformer via a power amplifier from a 2403Hz constant voltage oscillator The resulting current is then sensed by a detection CT An active filter is used to dampen earth current at commercial frequency and high frequency noise Example If we clamp around any grounding electrode in a multi grounded system the measured value of the electrode under test will be the resistance of
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