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®
1625
Earth/Ground Tester
Users Manual
January 2006
© 2006 Fluke Corporation, All rights reserved. Printed in USA
All product names are trademarks of their respective companies.

Summary of Contents

  • Page 1

    ® 1625 Earth/Ground Tester Users Manual January 2006 © 2006 Fluke Corporation, All rights reserved. Printed in USA All product names are trademarks of their respective companies.

  • Page 2

    Fluke's warranty obligation is limited, at Fluke's option, to refund of the purchase price, free of charge repair, or replacement of a defective product which is returned to a Fluke authorized service center within the warranty period.

  • Page 3: Table Of Contents

    Table of Contents Title Page Introduction ..................1 Models and Accessories................ 3 Safety Instructions ................4 Qualified Staff .................. 5 Setup ..................... 5 Unpacking..................5 Checking the Scope of Delivery ............5 General ....................6 Additional Accessories ................. 6 Assembly ....................7 Description of Functions...............

  • Page 4: Table Of Contents

    1625 Users Manual Measurement of Interference - Voltages and Frequencies....31 Measurement of Earthing Resistances..........32 3-pole/4-pole Measurement of Earthing Resistance ..... 33 Measurement of Single Earth Electrode Resistances in Mesh Operated Earthing Systems Using Selective Clamp Method ..................36 3-pole/4-pole Measurement of Single Earth Electrode Resistances ...................

  • Page 5

    List of Tables Table Title Page Models and Accessories ..........3 Electrical Measurement Specifications ......14 Description of Displays..........56...

  • Page 6

    1625 Users Manual...

  • Page 7

    List of Figures Figure Title Page Fluke 1625 Earth/Ground Tester........2 Description of Functions ..........8 Display ................10 Operating Elements ............21 Display Elements ............23 Operational Modes ............27 Measurement of Interference - Voltages and Frequencies..........32 Earthing Resistances Measurement - Method ....33 3-pole/4-pole Measurement of Earthing Resistance - Process................

  • Page 8

    1625 Users Manual...

  • Page 9: Introduction

    The effectiveness of grounding systems should be checked using a ground test instruments such as the 1625 which checks the effectiveness of connections to the ground. The 1625 provides the perfect solution by combining the latest technology into a compact, field-rugged and extremely easy to use instrument.

  • Page 10

    The terms earth and earthing also refer to ground and grounding and is used interchangeably throughout this manual. For stakeless earth resistance measurements, the EI-1625 must be purchased. (The EI-1625 comes standard with the 1625 Kit). Refer to Appendix A for a complete set of operating information including specifications.

  • Page 11: Models And Accessories, Models And Accessories

    Shielded Cable (Used w/EI-162X 2539195 Clamp) Clip-on Current Transformer (inducing) EI-162AC 12.7 Inch (320mm) Spilt Core Trans- EI-162BN former 2-3 Wire Adapter Cable for 1625 for EI- 2577171 162AC Current Transformer Earth Stake 2539121 Cable Reel w/25m Wire 2539100 Cable Reel w/50m Wire...

  • Page 12: Safety Instructions

    1625 Users Manual Safety Instructions W Warning This measuring equipment is only to be operated by quali- fied staff and in accord with its technical data in compli- ance with the safety precautions and instructions set forth below. In addition, use of this equipment requires compli- ance with the legal and safety instructions pertaining to the specific application in question.

  • Page 13: Qualified Staff, Setup, Unpacking, Checking The Scope Of Delivery

    Earth/Ground Tester Setup Qualified Staff Consists of persons familiar with the setting up, assembly, starting up and op- eration of the product and possess the qualifications required for such activi- ties, such as training, instruction and/or authorization to perform the following op- erations on circuits and equipment according to safety engineering standards: switching on and off, disconnecting, earthing/grounding, labeling;...

  • Page 14: General, Additional Accessories

    1625 Users Manual General Microprocessor controlled universal earth resistance meter with fully auto- mated measuring frequency selection process as well as automatic testing of probe- and auxiliary earth electrode resistances and possible interference volt- ages as per DIN IEC61557-5/EN61557-5. Measurement of interference voltage (U...

  • Page 15: Assembly, Description Of Functions

    The auxiliary power supply consists of 6 x 1.5 V batteries (IEC R6 or LR6 or type AA). This device has been developed, designed and manufactured in compliance with quality system DIN ISO 9001. Description of Functions The following flowchart presents a description of the functions of the 1625 Earth/Ground Tester.

  • Page 16

    1625 Users Manual Switching Current Voltage Supply Undervoltage Source measurement measurement voltage detection Display Processor driver Comp Relais Rotary selector driver switch buttons edw003.eps Figure 2. Description of Functions Measurement of Interference Voltage (U Fullwave rectification for DC and AC (DC without operational sign, AC signal sinus calibrated for r.m.s.

  • Page 17: Resistance Measurement (r~), Low Resistance Measurement (r )

    Earth/Ground Tester Description of Functions Measurement of Earthing Resistance (R The earthing resistance is determined by a 3- or 4-pole current and voltage measurement. The measuring voltage is a square pulse AC voltage with 48 / 20 V and a frequency of 94, 105, 111 or 128 Hz. The frequency can be selected manually or automatically (AFC).

  • Page 18: Lo-bat, Specifications

    1625 Users Manual LO-BAT Supervision of the battery charge status is done with a comparator circuit. Via microprocessor, a drop in battery capacity down to typ. 10 % of its specified value is indicated on the display with symbol LO-BAT.

  • Page 19

    Earth/Ground Tester Specifications Operation: Central rotary switch and function keys Working temperature range: -10 °C … +50 °C Operating temperature range: 0 °C … +35 °C Nominal temperature range: 18 °C … +28 °C Storage temperature range: -30 °C … +60 °C Note The chart of four temperature ranges for the instrument exist to sat- isfy European Standards requirements;...

  • Page 20

    1625 Users Manual Max voltage: socket A to socket EFGH Urms = 0 V Sockets ” E ES S H " to each other in any com- bination, max. Urms= 250 V (pertains to misuse) EMC (Emission Im- IEC 61326-1:1997 Class A...

  • Page 21

    Earth/Ground Tester Specifications Measurement of Interference Voltage DC + AC (U Measuring method: fullwave rectification Measuring Display Resolu- Frequency Limits of Er- Range Range tion Range 1…50 V 0.0…50 V 0.1 V DC/AC ± (5% of 45…400 Hz reading +5 sine digit) Measuring sequence:...

  • Page 22: Electrical Measurement Specifications

    1625 Users Manual Table 2. Electrical Measurement Specifications Requirements Intrinsic Er- Reference Con- or Test in Ac- Type ror or Influ- ditions or Speci- Designation cordance with ence Quan- fied Operating Code the Relevant Test tity Range Parts of IEC 1557...

  • Page 23

    Earth/Ground Tester Specifications intrinsic error 100% fiducial value variations routine test type test Max. Op- Measuring Instrinsic Display Range Resolution erating Range Error Error 0.001 ...2.999 0.001 3.00 ...29.99 0.01 0.020 30.0 ...299.9 ± ( 2 % of ± ( 5% of mv +2 digit ) mv +5 300 k...

  • Page 24

    1625 Users Manual fluencing conditions (see diagramm), the display shows a warning symbol W and a notice that RS or RH are too high. edw005.eps Automatic switchover of measuring resolution in dependence to auxiliary earth electrode resistance R RH with Umeas = 48 V...

  • Page 25

    Earth/Ground Tester Specifications Selective Measurement of the Earthing Resistance Measuring method: Current and voltage measurement with probe as per EN61557-5 and current measurement in the individual branch with additional current transformer (patent ap- plied for). Open circuit volt- 20 / 48 V AC age: Short circuit current: 250 mA AC...

  • Page 26

    1625 Users Manual Minimal current in single 0.5 mA with transformer (1000:1) branch to be measured: 0.1 mA with transformer (200:1) Max. interference current with a transformer (1000:1) through transformer: Resistance Measurement (R~) Measuring method: current and voltage measurement Measuring voltage:...

  • Page 27

    Earth/Ground Tester Specifications Resistance Measurement (R Measuring method: current- voltage measurement as per IEC61557-4 possible Open circuit voltage: 20 V DC Short circuit current: 200 mA DC Formation of measured with 4-pole measurement wires on H, S, ES can value: be extended without additional error.

  • Page 28: Compensation Of Lead Resistance (r )

    1625 Users Manual Compensation of Lead Resistance (R Compensation of lead resistance (R ) can be switched on in functions R 3pole, R 4pole A, R~ , and R F 2pole Formation of measured value: display measured compensated * Value of setpoint entry R = 0.000 , vari-...

  • Page 29

    Earth/Ground Tester Description of the Operating Elements Description of the Operating Elements Figure 4 illustrates the operating elements described below. 1625 EARTH / GROUND TESTER START H/C2 TEST DISPLAY S/ P2 MENU Resistance Earth/Ground Resistance 300k 300 k DC Low Resistance 3k...

  • Page 30

    1625 Users Manual D "CHANGE ITEM" button to change the set point entry values. E "SELECT" button to select the digit to be changed. F Display unit, liquid crystal digits, 18 mm high with automatic decimal point as well as active illumination.

  • Page 31: Description Of Displays

    Earth/Ground Tester Description of the Operating Elements Description of Display Elements The display (Figure 5) is divided into four display elements: 1. Digital display of measured value 2. Measuring function field to display measuring function 3. Unit field: V, , k , Hz 4.

  • Page 32: Procedure Of Measurements

    1625 Users Manual AC- resistance Earthing impedance (measuring frequency 55 Hz) Automatic-frequency-control TEST Measuring sequence in process LIMIT Limit value LIMIT Limit value exceeded Socket recognition EFGH Recognition of current transformer socket Message of an exceeded limit with beeper LO-BAT Battery voltage too low, replace batteries.

  • Page 33: Power On Functions

    Earth/Ground Tester Procedure of Measurements POWER ON Functions During switching on of the instrument with the central rotary switch it is pos- sible to access certain operating conditions by pressing certain button combina- tions: a) Standard mode If the device is put into operation without further button control, it switches into a battery saving condition (Stand by-display "---") approx.

  • Page 34: Operation

    1625 Users Manual e) Activation of display illumination By keeping the "CHANGE ITEM" button pressed during the switch on se- quence the display illumination is activated. Illumination fades away automati- cally if the instrument is switched to"Stand by" and, together with the instru- ment, is switched on again by pressing any button.

  • Page 35

    Earth/Ground Tester Procedure of Measurements ON/OFF CONTROL LOOP MEASURING LOOP POWER ON Function SELECT MEASURING 1 X START FUNTION WITH CENTRAL ROTARY SWITCH 1 X DISPLAY MEASUREMENT LIMIT 1 X DISPLAY DISPLAY, MEASURED VALUE SET VALUE OR OR SUPPLEMENTARY VALUE VOLTAGE MEASUREMENT 1 X CHANGE...

  • Page 36

    1625 Users Manual Control Loop After turning the function rotary switch, the voltage display mode is reached. Pushing "DISPLAY MENU" now calls up the control loop. According to the selected measuring function, different setting values can be displayed and changed in the control loop. The "DISPLAY MENU" button switches between the different set values inside a contiuous loop.

  • Page 37

    Earth/Ground Tester Procedure of Measurements 48 V/20 V selectable to 20 V with CODE 0.000 ... 29.99 in position R E 3pole only * I ( ratio ) 80 ... 1200 display only 4pole R E LIMIT 0.000 ... 999 k only if activated with CODE (warning-...

  • Page 38: Checking Of Correct Measuring Connection (socket Allocation)

    1625 Users Manual Measuring Loop This loop is entered by pressing the "START TEST" button. After releasing "START TEST" the last measured value stays on the display. By repeated pressing of the "DISPLAY MENU" button all supplementary values can be called.

  • Page 39: Safety Control Measurements, Measurement Of Interference - Voltages And Frequencies

    Earth/Ground Tester Procedure of Measurements Safety Control Measurements Before each measurement the instrument automatically checks the measuring conditions and, while simultaneously displaying the kind of error, prevents measurements from being started under the following conditions: excessive voltage on the sockets (> 24 V in RE and R~; > 3 V in wrong or incomplete connection Problems during the measuring sequence (display "E1 ...

  • Page 40: Measurement Of Earthing Resistances

    1625 Users Manual 1625 EARTH / GROUND TESTER START H /C2 TEST DISPLAY S/P2 MENU Resistance Earth/Ground Resistance 300 k 300 k DC Low Resistance 3k POLE POLE POLE POLE POLE POLE CHANGE ES/P1 ITEM POLE SELECT E /C1 Auxiliary...

  • Page 41: Pole/4-pole Measurement Of Earthing Resistance

    Earth/Ground Tester Procedure of Measurements To keep the instrument as simple as possible at the time of delivery, all special functions, such as LIMIT input, BEEPER programming, measurement of earthing impedance (R ) etc, are not activated at delivery. They can be acti- vated with personalized user's code (see "Changing of all Pre-set Data with Personalized Code").

  • Page 42

    1625 Users Manual 1625 EARTH / GROUND TESTER START H/C2 TEST DISPLAY S/P2 MENU Resistance 300 k DC Low Resistance 3k Earth/Ground Resistance 300k POLE 4 pole POLE POLE POLE POLE POLE CHANGE ES/P1 ITEM POLE SELECT E /C1 Auxiliary...

  • Page 43

    Earth/Ground Tester Procedure of Measurements An accuracy test of the results is made with another measurement following repositioning of the auxiliary earth electrode or probe. If the value stays the same, the distance is sufficient. If the measured value changes, probe or auxil- iary earth electrode must be repositioned until the measured value R stays constant.

  • Page 44: Method

    1625 Users Manual Measurement of Single Earth Electrode Resistances in Mesh Operated Earthing Systems Using Selective Clamp Method This measuring method has been created to measure single earth electrodes in permanently wired or mesh operated systems (e.g. lightning protection system with several electrodes or high voltage pylons with earth cabling etc.).

  • Page 45: Pole/4-pole Measurement Of Single Earth Electrode Resistances

    Earth/Ground Tester Procedure of Measurements Errors of the current transformer can be corrected as described in “Correcting Clip-on Transformer Error”. 3-pole/4-pole Measurement of Single Earth Electrode Re- sistances See Figure 12. 1625 EARTH / GROUND TESTER START H/C2 TEST DISPLAY S/P2...

  • Page 46

    1625 Users Manual Note The ratio that is preset from factory is correct for the EI162X sensing clamp Press "START TEST" button. Now a fully automated test sequence of all relevant parameters like auxiliary earth electrode, probe- and earth electrode resistance, is implemented and fin- ished with the display of the result R 1.

  • Page 47: Measurements On High Voltage Pylons

    Earth/Ground Tester Procedure of Measurements reliable values, the instrument offers the possibility of averaging over a longer period. 1. Select a fixed frequency (see "Control loop", Operation) 2. Keep the "START TEST" button pressed until the warning "measured value unstable" disappears. Max. averaging time is approx. 1 min. Measurements on High Voltage Pylons Measuring the Earthing Resistance without Disengaging the Overhead Earth Wire Using the Selective Clamp...

  • Page 48

    1625 Users Manual Accordingly, these equivalent resistances are displayed as: meas Therefore the earthing resistance R of the pylon is determined as a parallel circuit of the individual equivalent resistances: 1625 EARTH / GROUND TESTER START H/C2 TEST DISPLAY S/P2...

  • Page 49

    Earth/Ground Tester Procedure of Measurements 3. Press “START TEST” button Now a fully automated test sequence of all relevant parameters like auxiliary earth electrode, probe- and earth electrode resistance, is im- plemented and finishes with the display of the result R 4.

  • Page 50: Correcting Clip-on Transformer Errors

    1625 Users Manual Time average measurement: If there is a warning "measured value unstable" (see "Description of displays", Procedure of Measurement) after a test sequence, most likely it is caused by strong interference signals (e.g. unsteady noise voltage). Nevertheless, to get reliable values, the instrument offers the possibility of averanging over a longer period.

  • Page 51

    Earth/Ground Tester Procedure of Measurements 1625 EARTH / GROUND TESTER START H/C2 TEST DISPLAY S/P2 MENU Resistance Earth/Ground Resistance 300 k 300 k DC Low Resistance 3k POLE POLE POLE POLE POLE POLE CHANGE ES/P1 ITEM POLE E /C1 SELECT edw017.eps...

  • Page 52: Compensation Of Earth Electrode Connecting Lead

    1625 Users Manual Example: Your clip-on transformer has a transformation ratio of tr = 1000:1. The meas- urement without clip-on transformer results in a value R = 0.983 . With a clip-on transformer a value of R = 1.175 is measured.

  • Page 53: Measurement Of Soil Resistivity

    The measuring procedure applied below uses the method developed by Wenner (F.Wenner, A method of measuring earth resis- tivity; Bull. National Bureau of Standards, Bulletin 12 (4), Paper 258, S 478- 496; 1915/16). 1625 EARTH / GROUND TESTER START H/C2...

  • Page 54

    1625 Users Manual 1. Four earth spikes of the same length are positioned into the soil in an even line and with the same distance "a" to each other. The earth spikes should not be hammered in deeper than a maximum of 1/3 of "a".

  • Page 55

    Earth/Ground Tester Procedure of Measurements Distances of Probe edw021.eps Curve 1: As E decreases only deeper down, a deep earth electrode is advis- able Curve 2: As E decreases only down to point A, an increase in the depth deeper than A does not improve the values. Curve 3: With increasing depth E is not decreasing: a strip conductor elec- trode is advisable.

  • Page 56: Measurement Of Resistances, Resistance Measurement (r~)

    1625 Users Manual edw022.eps Measurement of Resistances Resistance Measurement (R~) This measuring function determines the ohmic resistance between 0.001 300 k . The measurement is done with AC voltage. For measurements of very low resistances a compensation of the connecting leads is suggested (see “Compensation of Measuring Lead Resistance”).

  • Page 57: Resistance Measurement (rf), Resistance Measurement (r )

    3 k can be measured with DC voltage and automatic polarity reversal as per EN61557-5. To achieve highest accuracy 4 pole measurements are possible. To balance the extension lead, a compensation has to be done. 1625 EARTH / GROUND TESTER START H/C2...

  • Page 58

    1625 Users Manual W Warning Due to the high measuring current inductive loads can cause lethal induced voltages during disconnection from the measuring circuit. 4. Start measurement with "START TEST" button. First, "R1" with positive voltage is measured on jack "E". After releasing the "START TEST"...

  • Page 59

    Earth/Ground Tester Procedure of Measurements Turning the central rotary switch for a short moment deletes the line compensation again. 1625 EARTH / GROUND TESTER START H/C2 TEST DISPLAY S/P2 MENU Resistance Earth/Ground Resistance 300 k 300 k DC Low Resistance 3k...

  • Page 60

    1625 Users Manual Standard Function Parameter Setting range presetting (AFC/94/105/111/128) Hz 48 V/20 V 3pole 0.000 ... 29.99 0.000 LIMIT On / Off R E LIMIT 0.000 ... 999 k 999 k }(Warning On/Off 4pole sound) On/Off (AFC/94/105/111/128) Hz 48 V/20 V 3pole 0.000...

  • Page 61: Storing A Code

    Earth/Ground Tester Procedure of Measurements 2pole 0.000 ... 29.99 0.000 LIMIT On/Off 4pole R LIMIT 0.000 ... 9,99 k 9.99 k }(Warning On/Off sound) Storing a Code 1. Press all 4 keys simultaneously and move central selector from OFF to the desired measuring mode. The display shows "C _ _ _".

  • Page 62: Deleting A Code

    1625 Users Manual 6. The changed value is stored by pressing the "DISPLAY MENU" key. 7. Pressing the "START TEST" key exits the setting program. Note If the limit values required by regulations are changed incorrect, er- roneous test results may be displayed.

  • Page 63

    Earth/Ground Tester Description of Displays Description of Displays Table 3. Description of Displays Function Displays Condition Note Before Stand by Turn rotary "START" position to switch or reduce push power button. All consump- measured tion values edw027.eps remain stored No or Apart from incorrect voltage...

  • Page 64

    1625 Users Manual Function Displays Condition Note Dangerous Apart from AC - vol- voltage tage > 50 measure- ment all measuring LIMIT functions edw031.eps are locked. Rotary Select cor- switch in rect posi- Before inter- tion. "START" mediate position edw033.eps...

  • Page 65

    Earth/Ground Tester Description of Displays Function Displays Condition Note Measuring Check lead circuit of connection earth- and on earth auxil. earth spikes electrode measuring discon- lead might edw037.eps nected. be defec- tive. Measuring Check lead circuit of connection earth- and on earth probe elec- spikes...

  • Page 66

    1625 Users Manual Function Displays Condition Note Display of Measured measured value is value ex- higher than ceeds set LIMIT. LIMIT. LIMIT edw041.eps Compen- Delete sation compensa- higher than tion or measured switch in- value. strument LIMIT ON/OFF. edw042.eps Wrong po-...

  • Page 67

    Earth/Ground Tester Description of Displays Function Displays Condition Note Operation Check bat- under teries. No reactions to button faulty con- Switch control etc. ditions. ON/OFF if still faulty, contact edw046.eps service. After Reverse Reverse "START" orientation clamp or of current see note clamp or on page...

  • Page 68: Care And Maintenance

    1625 Users Manual Function Displays Condition Note EE PROM contact memory service. access mal- function. edw050.eps Internal computa- tion mal- function. edw051.eps Thermal Cool thor- overload. oughly. edw052.eps Battery The internal voltage de- resistance of creases at the batteries 12MKH...

  • Page 69: Replacing Batteries

    Earth/Ground Tester Care and Maintenance detergent or spirit. Avoid aggressive cleaning agents and solvents (trilene, chlorothene etc.). Service work must only be undertaken by trained qualified staff. In all repair work care must be taken that the design parameters of the instru- ment are not modified to the detriment of safety, that assembled parts corre- spond to the original spares and that they are reassembled properly (factory state).

  • Page 70: Recalibration, Storage

    (in its original container if available) and forward it, postage paid, to the nearest Fluke Service Center. Include a brief description of the problem. Fluke assumes NO responsibility for damage in transit. To locate an authorized service center, call Fluke using any of the phone num- bers listed below: USA: 1-888-99-FLUKE (1-888-993-5853)

  • Page 71

    Stakeless Earth/Ground Resistance Testing Care and Maintenance Appendix A Stakeless Earth/Ground Resistance Testing Introduction Stakeless testing provides the ground tester with the unique capability to meas- ure individual ground resistances in multi-grounded systems using two clamp- on current transformers. The use of ground stakes is not necessary. Before this method was available, users were required to disconnect an indi- vidual ground path to be tested from other grounds to eliminate the influence of parallel ground paths.

  • Page 72: Specifications

    Specifications General: Adapter unit for use with ground testers in the mode: 3 pole (Order No. EI-1625) All information contained in this section exclusively refers to this application. Principle: Ground testing without using earth stakes for the probe and the auxiliary earth elec- trode.

  • Page 73: Principle Of Operation, Purpose

    Stakeless Earth/Ground Resistance Testing Principle of Operation Dimensions Total length of adaptercable 1,8 m, Length of shielded cable to clamp-on CT 1,5 m. Operating error*: ± (10% of m.v. + 5 digit). Display range*: 0,010 Ω ... 130 Ω. Measuring frequency: 128 Hz.

  • Page 74

    1625 Users Manual Equivalent diagram Source edw061.eps...

  • Page 75

    Stakeless Earth/Ground Resistance Testing Principle of Operation If the parallel connection of resistors, R1...Rn is considerably lower than the ground connection under test R then is a reasonable approximation. The test voltage (U) is applied without disconnecting ground rod and/or the direct electrical connection by means of a clamp-on current transformer and the current detected by a second current transformer.

  • Page 76

    1625 Users Manual Operation Connect the adapter according to the diagram and the designations E, S and H (C1, P1 and P2 for US-version) to the tester and to a current clamp. 1625 EARTH / GROUND TESTER START H/C2 TEST...

  • Page 77: Settings On The Tester

    Stakeless Earth/Ground Resistance Testing Principle of Operation Erder >10 cm edw064.eps Pushing the START-button will display the value of R Note In this particular mode the values of RH and RS have no meaning. Settings on the Tester Refer to the Operation section in the Testers instruction manual. The rotary switch of the tester must be in the R 3 pole position.

  • Page 78: Applications

    1625 Users Manual Applications Example1: Ground rod on power poles. edw065.eps Example 2: Tests on multi-grounded (inter-connected) systems: Ground conductors are for example bonded to grids or concrete-footing grounds and other conducting elements such as lightning protection systems or frameworks.

  • Page 79

    Stakeless Earth/Ground Resistance Testing Principle of Operation Lightning Protection Framework Footing ground edw066.eps...

  • Page 80

    1625 Users Manual Description of Displays With stakeless ground testing some display combinations have certain signifi- cance. Display Significance Note Polarity of Turn one CT’s is re- versed edw067.eps Resistance Switch under test is on/off for below meas- next test...

  • Page 81

    Stakeless Earth/Ground Resistance Testing Principle of Operation Display Significance Note Resistance under test is above measuring range edw069.eps Legend: W= displayed flashing...

  • Page 82

    Appendix B Earthing Resistance Introduction Per definition, the earthing resistance consists of several individual resistances. 1. The resistance of connecting lead to earth electrode 2. The resistance of the actual earth electrode; earthing rod, earthing plate, earthing strip, mesh earth electrode etc. 3.

  • Page 83

    Earthing Resistance Principle of Operation Soil Re- Earthing Resistance ( ) Type of sitivity Soil Earthing Rod m Earthing Strip m Depth Moist humus soil, moor soil, swamp Farming soil,loam y and clay soils Sandy clay soils Moist sandy soil 1000 sandy soil...

  • Page 84

    1625 Users Manual Soil Resistivity The soil resistivity is the resistance measured between two opposing surfaces of a cube of homogenous soil material with a lateral length of 1 meter. The unit is m (see picture) A = 1 m L=1 m edw054.eps...

  • Page 85

    Earthing Resistance Principle of Operation July Jan. Dec. month edw055.eps Temporal change of the earthing resistance of a conductor earth electrode (earth strip, earth cable). July Jan. Dec. month edw056.eps Temporal change of the earthing resistance of a buried earth electrode (earth pipe, earth plate)

  • Page 86

    1625 Users Manual Measuring Method The current voltage measuring method is based on the block diagram circuit shown in the figure below. U meas. edw057.eps An AC generator G feeds current I via earth electrode E (earth electrode resis- tance R...

  • Page 87

    Earthing Resistance Principle of Operation The Potential Gradient Area Around every earth electrode a so called potential gradient area develops dur- ing the flow of an electric current (see picture below). 40 60 m edw058.eps If the voltage between the earth electrode and a probe with a distance "a" from the earth electrode is measured, the value increases less with increasing dis- tance.

  • Page 88

    1625 Users Manual The Influence of Potential Gradient Areas on Earth Resis- tance Measurement To pick off the true voltage drop from the earthing resistance (= the resistance between the earth electrode and the soil potential F ) it is to be assured that the probe is set outside the potential gradient area of all connected earth electrodes and the auxiliary earth electrode H.

  • Page 89

    Earthing Resistance Principle of Operation Earth Impedance (R*) on High Voltage Transmission Lines The earthings of transmission line pylons are interconnected via the overhead earth wire. This wire is not only ohmic. There is also inductivity and resistivity (L´, R´). For calculation of the short circuit current this impedance at line frequency has to be determined.

  • Page 90

    1625 Users Manual...

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