User`s Manual Ground Resistance Clamp On Tester
Contents
1. OL is displayed 4 Once the desired value is set press the FUNC button a second time to view and adjust the LO alarm value 5 Press the FUNC button three more times to exit the setting mode 6 The meter will now compare the measured resistance value with the high and low limits when the meter is set to the e position If the reading is larger than the HI value the meter will beep and display HI on the LCD If the reading is lower than the LO value the meter will beep and display LO on the LCD Data Logging Setting the Sampling Time 1 Press the FUNC button three times until the SEC symbol appears in the LCD display 2 The sampling rate is now displayed in seconds 3 Press the A or the VW button to increase or decrease the value The value can be incremented from 0 to 255 seconds 4 Once the desired value is set press the FUNC button several times until the characters in the upper row of the LCD disappear Recording Data 1 Press the REC button to start recording data at the specified sampling rate The REC symbol will appear on the top of the LCD display To stop recording press the REC button The REC symbol will no longer be displayed on the LCD NOTE Data logging will automatically stop if the memory is filled 116 records or if the meter detects a low battery condition NOTE If the sampling interval is set to 0 only one sample will be recorded To record another sa2. manual 11 Model 382357 Version 1 0 J une 2004 Maintenance General Care Store the ground resistance tester and reference loop in its case when not in use A damp cloth may be used to clean any surface dirt from the meter Never use harsh detergents abrasives solvents or cleaners on the meter Battery Replacement When the low battery symbol appears on the display replace the meter s 9V battery Use a high quality alkaline battery whenever replacement becomes necessary 1 Remove the two rear screws and open the meter housing 2 Replace the battery close the meter housing and affix the two rear screws Clamp Jaw Maintenance The jaws may be brushed clean with a toothbrush or similar soft bristled brush Care must be taken to ensure that the contact fins are not bent or deformed as this will affect the operation of the meter Calibration and Repair Services Extech offers repair and calibration services for the products we sell Extech also provides NIST certification for most products Call the Customer Service Department for information on calibration services available for this product Extech recommends that annual calibrations be performed to verify meter performance and accuracy Support line 781 890 7440 Technical support Extension 200 E mail support extech com Repair amp Returns Extension 210 E mail repair extech com Product specifications subject to change without notice For the lates
3. 4 Model 382357 Version 1 0 J une 2004 Ground Resistance Autorange Specifications Range Resolution Accuracy of reading 0 025 to 0 250Q 0 0020 1 5 0 050 0 250 to 1 0000 0 020 1 5 0 05Q 1 001 to 9 9990 0 020 1 5 0 10 10 00 to 50 00Q 0 040 1 5 0 10 50 01 to 99 99Q 0 040 1 5 0 50 100 0 to 200 00 0 40 1 5 1 00 200 1 to 400 0Q 20 5 0 5Q 400 0 to 600 00 50 10 10Q 600 1 to 1500Q 200 20 conductor centered Accuracy Note Loop resistance non inductive external field lt 50A m external electrical field lt 1 V m Ground Leakage Current Specifications Range Accuracy of reading 0 200 to 1 000mA 2 0 0 05mA 1 00 to 10 00mA 2 0 0 03mA 10 0 to 100 0mA 2 0 0 3mA 100 to 1000mA 2 0 0 3mA 0 20 to 4 00A 2 0 0 03A 4 00 to 30 00A 3 0 0 03A Notes Auto range 50 60Hz bandwidth True RMS sensing Crest Factor lt 3 0 High and Low Alarm Range Resolution High Alarm 0 15000 10 5 Model 382357 Version 1 0 J une 2004 Operation Note Ensure that the jaws are fully closed before testing Note DO NOT clamp on to any conductor or open the clamp jaws during the start up self calibration self cal is identified by the LCD counting down from CAL5 to CAL1 Ground Resistance Measure
4. User s Manual EXT INSTRUMENTS Ground Resistance Clamp On Tester MODEL 382357 CAT Ill 300V CAT III 600V Warranty EXTECH INSTRUMENTS CORPORATION warrants the basic instrument to be free of defects in parts and workmanship for one year from date of shipment a six month limited warranty applies on sensors and cables If it should become necessary to return the instrument for service during or beyond the warranty period contact the Customer Service Department at 781 890 7440 EXTENSION 210 for authorization or visit www extech com for more information A Return Authorization RA number must be issued before any product is retumed to Extech The sender is responsible for shipping charges freight insurance and proper packaging to prevent damage in transit This warranty does not apply to defects resulting from action of the user such as misuse improper wiring operation outside of specification improper maintenance or repair or unauthorized modification Extech specifically disclaims any implied warranties or merchantability or fitness for a specific purpose and will not be liable for any direct indirect incidental or consequential damages E xtech s total liability is limited to repair or replacement of the product The warranty set forth above is inclusive and no other warranty whether written or oral is expressed or implied Introduction Congratulations on your purchase of Extech s 382357 Ground Resista
5. clamping on to the ground electrode or rod 4 Slight amounts of drift may occur at high resistance measurements this is normal and should not be cause for concern Blank display or any failure mode Replace the battery before proceeding Start up Initialization Failure The start up calibration will continue indefinitely if the jaws are open or dirty Check that the jaws mating surfaces are clean Do not open the jaws while the initialization sequence is running Noise on the Ground Electrode or Rod If noise is present over 3A or 30V on the ground electrode or rod the word NOISE will appear on the display and readings can no longer be considered accurate Before the meter can be used accurately the noise problem must be addressed Reference Test Loop The reference test loop is a set of resistors that provides a means to check the performance of the meter 1 Open the measurement jaws and check that the mating surfaces are clean and free of dust dirt or any foreign substances Clean if necessary 2 Clamp the meter around the reference loop as shown in the diagram 3 Give the meter a few seconds to settle and read the measurement The meter should display approximately the same value as marked on the reference loop taking into consideration the accuracy listed in the specification chart If the readings are not similar to what is marked on the reference loop consult the Trouble Shooting and Maintenance sections of this
6. e any protective covering from the ground conductor 2 Turn the meter switch to the Ohm Q function 3 Once the start up calibration procedure is completed clamp on to an electrode or ground rod 4 Allow several seconds for the meter to settle and then note the reading Cellular Transmission Towers WARNING Use extreme care when making measurements around transmission towers High Voltage may be present The ground conductor should be located at the base of the tower but your configuration may be different 1 Locate the ground conductor 2 Clamp around the ground conductor You should place the clamp before any splices bonds or other splits in the ground system 3 Read the measured reading Primary Transmission Ground Conductor Tower Branch Ground Conductors 9 Model 382357 Version 1 0 J une 2004 Service Entrance Note Multiple ground rods multiple grounds i e ground rod s and water pipe grounds or a combination may be present depending on the particular situation In these situations it is necessary to make your measurements between the service entrance neutral and all subsequent ground points Distibution Panel Water Pipe 10 Model 382357 Version 1 0 J une 2004 Troubleshooting 1 Snap the jaws open and closed two or three times before turning the meter on 2 Do not clamp on to any device during the power up initialization sequence 3 Snap the jaws two or three times after
7. ments 1 Open the clamp jaws and check that all surfaces are clean and free of dust dirt or any foreign substances Clean if necessary 2 Forcefully snap the clamp jaws open and closed several times 3 Turn the meter on by moving the rotary switch to the ohms Q position DO NOT interrupt the start up procedure by opening the clamp jaws or clamping around a conductor During self calibration the meter will display CAL5 CAL4 CAL3 CAL2 and CAL1 Typical application 4 Once the start up calibration procedure is completed the meter will sound a beep Clamp on to an electrode or ground rod and read the value of ground resistance on the display Ground Leakage Current Measurement 1 Turn the meter on by moving the rotary switch to the mA or A position 2 Clamp on to the electrode or conductor 3 Read the value of leakage current displayed on the LCD HOLD Press the HOLD button to freeze the reading in the display g will appear in the display Press HOLD again to exit the function 6 Model 382357 Version 1 0 J une 2004 High and Low Alarm 1 Turn the meter on by moving the rotary switch to the e position 2 Press the FUNC button to view and adjust the HI alarm value 3 Press A or the V button to increase or decrease the value Hold down the button to increase the speed of adjustment The value can be incremented from 0 to 1500 ohms and then OL overload The value will roll over to 0 after
8. mple press REC again Recalling Stored Data 1 Press the FUNC button four times until the NO symbol is displayed on the LCD The current record number will be displayed in the top row and the data will be displayed below it 2 Press the A or the W button to step through and read the data in the next memory location Holding down the button will increase the speed of the incrementing value Clearing Data Memory 1 With the meter powered off press and hold down the REC button while turning the meter on The CL symbol will appear on the display indicating that memory has been cleared 7 Model 382357 Version 1 0 J une 2004 Measurement Principles Typical multi grounded distribution system Reg If the parallel ground resistances Ri R2 Ra etc up to Rn are combined as Reg then only Rg and Reg are left in the circuit A R y g If a constant voltage is applied to the circuit the following equation applies V 1 ee where Ra i 1 2 n 1 pe R If Rg and Ri Ra R3 Rn are approximately the same and n is large 200 for example then Reg will be much less then Rg and may possibly approach zero Example If Rg and Rj Ra R3 Rn are all 10Q respectively and n 200 then Reg by calculation equals 1 R U Q a i 0 05 10 10 10 r R R 10 0 05 10 05 gt R I 8 Model 382357 Version 1 0 J une 2004 Applications Telephone Electrical Ground Rods 1 Remov
9. nce Tester This Clamp on device allows the user to measure ground resistance without the use of auxiliary ground rods This device can only be used on multi grounded systems It is not necessary to disconnect the ground under test Proper use and care of this meter will yield years of reliable service Safety Only qualified technicians should operate this meter Use extreme caution when operating the meter near energized electrical equipment Do not attempt to use this meter to twist or pry the ground electrode or ground wire away from grounded equipment All metal objects or wires connected to the electrical system under test should be assumed to be lethal until tested Grounded systems are no exception Ensure that the batteries are inserted correctly in the battery compartment Remove the batteries from the meter if the meter is to be stored for long periods WARNING If the meter is used in a manner not specified by the manufacturer the built in protections provided by the meter may be impaired International Safety Symbols This symbol adjacent to another symbol or terminal indicates the user must refer to the manual for further information This symbol adjacent to a terminal indicates that under normal use hazardous voltages may be present 2 Model 382357 Version 1 0 J une 2004 Description Hold Button LCD Display Oo ON oO oOo fF amp N Jaw Assembly Rotary Selector Switch A increme
10. nt Button Function Button Measurement Trigger CO Cou Record Button EXTEGH uam Vv decrement Button Display Symbols REC Ohms resistance measurement milli amperes Amperes current measurements Hi Lo alarm position Excessive noise on the ground conductor or rod Clamp jaws are not fully closed Low Battery Indicates data logging in progress Indicates the READ function Hold function activated 3 Model 382357 Version 1 0 J une 2004 Specifications General Specifications Resistance Test Frequency Max Conductor size Display Sampling rate Power supply Power consumption Battery Life Temp Coefficient Current Overload Continuity check Range selection Safety Operating conditions Storage conditions Dimensions Weight Accessories 3 333 kHz 15mV rms approx 0 9 23mm 4 digit 9999 count display 0 5 seconds One 9V battery 40mADC 3000 measurements 0 15 times the specified accuracy per C from 39 to 64 F 4 to 18 C and 82 to 122 F 28 to 50 C Protected to 100A Continuous 200A for less than 60 seconds 50 60Hz Audible tone if reading is less than approx 40Q Automatic ranging Meets the requirements for IEC1010 1 Category III 300V and Category II 600 V 14 to 122 F Oto 50 C with lt 85 RH 4 to 122 F 20 to 60 C with lt 75 RH 10 1 x 3 9 x 1 9 257 x 100 x 47mm 1 4lbs 640g Resistance check plate 9V battery amp carrying case
11. t version of this User s Guide Software updates and other up to the minute product information visit our website www extech com Copyright 2004 Extech Instruments Corporation All rights reserved including the right of reproduction in whole or in part in any form 12 Model 382357 Version 1 0 J une 2004
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