Related Manuals for AEMC 4620
Summary of Contents for AEMC 4620
- Page 1 4620 DIGITAL GROUND RESISTANCE AND SOIL 4630 RESISTIVITY TESTERS E N G L I S H User Manual...
- Page 2 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 #: ______________________________ Model #:...
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Page 3: Table Of Contents
3.5 Auto-ranging ................13 4. GROUNDING THEORY ............... 14 4.1 Grounding Electrode Resistance ..........14 4.1.1 Effect of Electrode Size/Depth on Resistance ....16 4.1.2 Effects of Soil Resistivity on Electrode Resistance ..17 4.1.3 Factors Affecting Soil Resistivity .........17 4.1.4 Effect of Ground Rod Depth on Resistance ....20 4.2 Ground Resistance Values .............21 4.3 Ground Resistance Testing Principle ........23 4.3.1 Position of Auxiliary Electrodes in Measurements ..24 Digital Ground Resistance Tester Model 4620 and 4630... - Page 4 6.2 Disassembly ................37 6.3 Power Supply ................38 6.3.1 Testing the Battery ............38 6.3.2 Replacing the Battery (Model 4620) ......39 6.3.3 Recharging the Battery (Model 4630) ......39 6.3.4 Replacing the Safety Fuse ..........40 6.4 Cleaning ..................40 6.5 Storage ...................40 Repair and Calibration ..............41 Technical and Sales Assistance ............41 Limited Warranty ................42 Warranty Repairs ................42 Digital Ground Resistance Tester Model 4620 and 4630...
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Page 5: Introduction
• 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 sys- tems are no exception. • Use extreme caution when using the instrument around ener- gized electrical equipment. • Never attempt to use the instrument to twist or pry the ground electrode or ground wire away from the equipment being grounded. • AEMC Instruments considers the use of rubber gloves to be ® an excellent safety practice even if the equipment is properly operated and correctly grounded. • Always inspect the instrument and leads prior to use. Replace any defective parts immediately. Digital Ground Resistance Tester Model 4620 and 4630... -
Page 6: International Electrical Symbols
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, make sure that the contents are consistent with the ordering information. 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. Do not use equipment which is damaged or appears to be damaged. Digital Ground Resistance Tester Model 4620 and 4630... -
Page 7: Ordering Information
Ground Resistance Tester Model 4620 Kit (150 ft) ..Cat. #2135.19 Includes ground tester, two 150 ft color-coded leads on spools (red/blue), one 30 ft lead (green), two T-shaped auxiliary ground electrodes, set of 5 spaded lugs, one 100 ft AEMC ®... -
Page 8: Kits, Accessories And Replacement Parts
Test Kit for 3-Point Testing (150 ft) ........Cat. #2135.35 Includes two 150 ft color-coded leads on spools (red/blue), one 30 ft lead (green), two T- shaped auxiliary ground electrodes, set of 5 spaded lugs, one 100 ft AEMC tape measure ®... -
Page 9: Product Features
9. Display (with backlight - lights up when the TEST button is pressed) 4. Input terminal Xv (ES) 10. Fuse holder 5. Input terminal X (E) 11. TEST button 6. X-Z Fault indicator (when released, turns the unit OFF) Digital Ground Resistance Tester Model 4620 and 4630... -
Page 10: Control And Connector Features (Model 4630)
3. Input terminal Z (H) 9. Xv-Y High Noise indicator 10. Display (with backlight) 4. Input terminal Y (S) 5. Input terminal Xv (ES) 11. Fuse holder 12. Test button 6. Input terminal X (E) Digital Ground Resistance Tester Model 4620 and 4630... -
Page 11: Fault Indicator Leds
• Occasionally, a stray voltage above 4.5V may also set off this light. • Check the leads for a possible solution. 2.3.3 Xv-Y High Noise This LED signals the presence of excessive electrical noise (13V peak approx) in the voltage circuit (between Xv and Y or X and Y). • One remedy is to use shielded leads from the instrument to the auxiliary electrodes. • Connect all the shields to the rod under test. Digital Ground Resistance Tester Model 4620 and 4630... -
Page 12: Buzzer
• If high electrode resistance still exists after properly inserting aux- iliary electrodes into the earth, try pouring water on and around the auxiliary electrodes. This will improve their electrical connec- tion to earth. • If stray currents are suspected, one solution to reduce their influ- ence is to move both Y and Z electrodes in an arc relative to the X electrode (try, e.g. a 90° shift), and test again. • Display of 0.00: Xv and Y are short-circuited. • Display of <0: X and Z or Xv and Y rods are reversed. NOTE: Accuracy may be affected by auxiliary ground rod (Ry, Rz) resistance levels and by stray signal levels (earth currents). Digital Ground Resistance Tester Model 4620 and 4630... -
Page 13: Specifications
45 to 55%, battery power at 9.5V, auxiliary resistance at the measurement terminals = 0, no stray voltage, an electrical field < 1V/m, and a magnetic field from 0 to 40A/m. Voltage Detection Range: 20 to 250V between the X and Z terminals or between the Xv and Z terminals. Frequency: DC at 450Hz Voltage Withstanding: Both models are fuse protected. In the event of a system fault, the units can withstand 250V or 100V Fuse Protection: High breaking capacity - 0.1A, >250V, 0.25 x 1.25" Digital Ground Resistance Tester Model 4620 and 4630... -
Page 14: Mechanical
Battery Life: 2000 measurements of 15 seconds each Battery Charging: External recharge - 120-230V /50-60Hz, 20VA Charge time - 6 hrs to attain 80% of the battery capacity Low Battery Indicator: If the “CHARGE” indicator turns on solid RED, the battery needs to be charged. Mechanical Connection: Color-coded terminals accept spade lugs with minimum gap of 6mm or standard 4mm banana jacks. Display: 2000-count 7 segment LCD, approx 1" high (3-1/2 digit) LCD also indicates overrange, test lead shorts and lead reversals. Blue electroluminescent backlight. Dimensions: 10.8 x 9.7 x 5.0" (273 x 247 x 127mm) Weight: Model 4620: 6.28 lbs (2.85kg) Model 4630: 7.38 lbs (3.35kg) Colors: Case - safety yellow; Front panel - gray Mechanical Protection: The Models 4620 and 4630 have successfully undergone all the required mechanical tests and therefore meet all the requirements of the standards EN 61557 and EN 61010-1. Digital Ground Resistance Tester Model 4620 and 4630... -
Page 15: Environmental
Operating Temperature: 14° to 131°F (-10° to 55°C), 0 to 90% RH Storage Temperature: -40° to 158°F (-40° to 70°C), 0 to 90% RH with batteries removed Safety Electrical: EN 61010-1 + A2 (ed. 95) EN 61557 (ed. 97) 30Vrms, CAT III, Pollution Degree 2 Electromagnetic Compatibility: EN 61326-1 (ed.98) *Specifications are subject to change without notice Auto-ranging The selection of the measurement current is depending on the resistance to measure. When the instrument is turned ON, the measurement starts on the smallest current range (100µA). If the measurement is between 185 and 1950cts, the range stays the same (100µA). If the measurement is under 185cts, the current is multiplied by 10 (within 10mA max). If it is above 1950cts, the current is divided by 10 (without going under 100µA). This is done to avoid switching back and forth between ranges when you are measuring 190Ω. It is possible to display 190.0 or 190Ω depending on the automatic range selection. Digital Ground Resistance Tester Model 4620 and 4630... -
Page 16: Grounding Theory
B) The National Institute of Standard and Technology (N.I.S.T.) has demonstrated that the resistance between the electrode and the surrounding earth is negligible if the electrode is free of paint, grease or other coating, and if the earth is firmly packed. Ground Rod and Clamp Contact Resistance Between Rod and Soil Concentric Shells of Earth Figure 3 Digital Ground Resistance Tester Model 4620 and 4630... - Page 17 The equations for systems of electrodes are very complex and often expressed only as approximations. The most commonly used formula for single ground electrode systems, developed by Professor H. R. Dwight of the Massachusetts Institute of Technology, follows: ρ π R = resistance in ohms of the ground rod to the earth (or soil) L = grounding electrode length r = grounding electrode radius ρ = average resistivity in ohms-cm Digital Ground Resistance Tester Model 4620 and 4630...
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Page 18: Effect Of Electrode Size/Depth On Resistance
Depth: As a ground rod is driven deeper into the earth, its resistance is substantially reduced. In general, doubling the rod length reduces the resistance by an additional 40%. 1" dia. 1/2" dia. 35 40 Driven Depth in Feet Ground Resistance Versus Ground Rod Depth Figure 5 Digital Ground Resistance Tester Model 4620 and 4630... -
Page 19: Effects Of Soil Resistivity On Electrode Resistance
Same, with varying proportions 1020 15,800 135,000 of sand and gravel Gravel, sand, stones with 59,000 94,000 458,000 little clay or loam Table 1 4.1.3 Factors Affecting Soil Resistivity Two samples of soil, when thoroughly dried, may become in fact very good insulators, having a resistivity in excess of 10 ohm-centimeters. The resis- tivity of the soil sample is seen to change quite rapidly until approximately twenty percent or greater moisture content is reached. Digital Ground Resistance Tester Model 4620 and 4630... - Page 20 13,800 32 (ice) 30,000 79,000 330,000 Table 3 Because soil resistivity directly relates to moisture content and temper- ature, it is reasonable to assume that the resistance of any grounding system will vary throughout the different seasons of the year. Such varia- tions are shown in Figure 6 below. Digital Ground Resistance Tester Model 4620 and 4630...
- Page 21 The Effect of Salt* Content on the Resistivity of Soil (sandy loam, moisture content, 15% by weight, temperature 17°C) Added Salt Resistivity % by weight of moisture (Ohm-centimeters) 10,700 1800 Table 4 Digital Ground Resistance Tester Model 4620 and 4630...
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Page 22: Effect Of Ground Rod Depth On Resistance
*Such as copper sulfate, sodium carbonate and others. Salts must be EPA or local ordinance approved prior to use. 4.1.4 Effect of Ground Rod Depth on Resistance To assist the engineer in determining the approximate ground rod depth required to obtain a desired resistance, a device called the Grounding Nomograph may be used. The Nomograph, shown in Figure 7, indicates that to obtain a grounding resistance of 20 ohms in a soil with a resistivity of 10,000 ohm-centimeters, a 5/8" OD rod must be driven 20 ft. Note that the values indicated on the Nomograph are based on the assumption that the soil is homogeneous and, therefore, has uniform resistivity. The Nomo- graph value is an approximation. Digital Ground Resistance Tester Model 4620 and 4630... -
Page 23: Ground Resistance Values
3. Lay straightedge on R and P scale, and allow to intersect with K scale. 4. Mark K scale point. 5. Lay straightedge on K scale point and DIA scale, and allow to intersect with D scale. 6. Point on D scale will be rod depth required for resistance on R scale. Ground Resistance Values 2008 article 250.56 regarding the resistance of rod, pipe and plate ® electrodes states that if the rod, pipe, or plate does not have a resistance of 25Ω or less to ground shall be augmented by one additional electrode of any of the types specified by 250.52 (A)(4) through (A)(8). Where multiple rod, pipe or plate electrodes are installed to meet the requirements of the section, they shall not be less than 6 feet apart. Digital Ground Resistance Tester Model 4620 and 4630... - Page 24 Electrically connecting to existing water and gas distribution systems was often considered to yield low ground resistance; however, recent design changes utilizing non-metallic pipes and insulating joints have made this method of obtaining a low resistance ground questionable and in many instances unreliable. Auxiliary ground electrodes will be required in high voltage transmission lines, where maximum resistance of 15 ohms is recommended, and in distribution lines, where maximum resistance of 25 ohms is preferred. All electrical systems constructed in accordance with the National Electrical Code , should not exceed 25 ohms. ® Digital Ground Resistance Tester Model 4620 and 4630...
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Page 25: Ground Resistance Testing Principle
Ground Resistance Testing Principle (Fall-of-Potential — 3-Point Measurement) 3-Point measurement is used to measure resistance to ground of auxiliary ground electrodes and grids. The potential difference between rods X and Y is measured by a voltmeter, and the current flow between rods X and Z is measured by an ammeter. By Ohm’s Law E = RI or R = E/I, we may obtain the ground electrode resistance R. If E = 20V and I = 1 A, then: R = = = 20 ohms It is not necessary to carry out all the measurements when using a ground tester. The ground tester will measure directly by generating its own cur- rent and displaying the resistance of the ground electrode. Digital Ground Resistance Tester Model 4620 and 4630... -
Page 26: Position Of Auxiliary Electrodes In Measurements
EARTH Figure 8 NOTE: Terminals X and Xv are shorted together in 3-Point measurement. 4.3.1 Position of the Auxiliary Electrodes in Measurements The goal in precisely measuring the resistance to ground is to place the auxiliary current electrode Z far enough from the ground electrode under test so that the auxiliary potential electrode Y will be outside of the effec- tive resistance areas of both the ground electrode and the auxiliary current electrode. The best way to find out if the auxiliary potential rod Y is outside the effective resistance areas is to move it between X and Z and to take a reading at each location. If the auxiliary potential rod Y is in an effective resistance area (or in both if they overlap), by displacing it, the readings taken will vary noticeably in value. Under these conditions, no exact value for the resistance to ground may be determined. Digital Ground Resistance Tester Model 4620 and 4630... - Page 27 On the other hand, if the auxiliary potential rod Y is located outside of the effective resistance areas, as Y is moved back and forth the reading variation is minimal. The readings taken should be relatively close to each other, and are the best values for the resistance to ground of the ground X. The readings should be plotted to ensure that they lie in a “plateau” region as shown in Figure 10. Y Y Y'' Effective Resistance Areas (No Overlap) Reading Variation X-Y Distance Figure 10 Digital Ground Resistance Tester Model 4620 and 4630...
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Page 28: Measuring Resistance Of Ground Electrodes
If readings were taken by moving the auxiliary potential electrode Y towards either X or Z, the reading differentials would be great and one could not obtain a reading within a reasonable band of tolerance. The sensitive areas overlap and act constantly to increase resistance as Y is moved away from X. Digital Ground Resistance Tester Model 4620 and 4630... - Page 29 Under Test Electrode Electrode Effective 62% of D 38% of D Resistance Areas Do Resistance of Not Overlap Auxiliary Current Electrode Resistance of Earth Electrode Distance from Y to Ground Electrode Figure 13 Digital Ground Resistance Tester Model 4620 and 4630...
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Page 30: Auxiliary Electrode Spacing
20 ft 74 ft 120 ft 30 ft 86 ft 140 ft Table 6 Multiple Electrode System A single driven ground electrode is an economical and simple means of making a good ground system, but sometimes a single rod will not provide sufficient low resistance, and several ground electrodes will be driven and connected in parallel by a cable. Very often when two, three or four ground electrodes are used, they are driven in a straight line. When four or more are used, a hollow square con- figuration is used and the ground electrodes are still connected in parallel and equally spaced (Figure 14). In multiple electrode systems, the 62% method electrode spacing may no longer be applied directly. The distance of the auxiliary electrodes is now based on the maximum grid distance (e.g. in a square, the diagonal; in a line, the total length). A square having a side of 20 ft will have a diagonal of approximately 28 ft. Digital Ground Resistance Tester Model 4620 and 4630... - Page 31 120 ft 341 ft 550 ft 140 ft 372 ft 600 ft 160 ft 390 ft 630 ft 180 ft 434 ft 700 ft 200 ft 453 ft 730 ft Table 7 Digital Ground Resistance Tester Model 4620 and 4630...
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Page 32: Operation
Current may be flowing and a dangerous potential could exist between the disconnected wires. • X and Xv (E, ES) are shorted • Disconnect shorting link between Y and Z (S, H) • Connect X to the ground rod to be tested • Connect Y (S) to the center electrode • Connect Z (H) to the outer electrode • Depress the “Test” button to measure ground resistance Digital Ground Resistance Tester Model 4620 and 4630... -
Page 33: 2-Point Measurement (Simplified Measurement)
Procedure: • Short X and Xv (E, ES) • Short Y and Z (S, H) • Connect X to ground rod to be measured • Connect Z to an electrode • Measure as in the 3-Point method Grounding conductor Metallic Water Pipe (Y-Z shorted) Ground Utility level pole Ω Ground Butt plate Terminals shorted Figure 16 Digital Ground Resistance Tester Model 4620 and 4630... -
Page 34: Continuity Measurement
1. Such data is used to make sub-surface geophysical surveys as an aid in identifying ore locations, depth to bedrock and other geological phenomena. 2. Resistivity has a direct impact on the degree of corrosion in under- ground pipelines. A decrease in resistivity relates to an increase in corrosive activity and therefore dictates the protective treatment to be used. Digital Ground Resistance Tester Model 4620 and 4630... -
Page 35: Types Of Resistivity Measurements
Instruments Model 4620 ® and 4630 Ground Testers. The 4-Point method, as the name implies, requires the insertion of four equally spaced, in-line elec- trodes into the test area. A known current from a constant current generator is passed between the outermost electrodes (X and Z). The potential drop (a function of the resistance) is then measured across the two innermost electrodes (Xv and Y). The Models 4620 and 4630 are calibrated to read directly in ohms. Ω X electrode Xv electrode Y electrode Z electrode b< Figure 18 Digital Ground Resistance Tester Model 4620 and 4630... -
Page 36: Soil Resistivity Measurement Procedure (4-Point)
ρ = resistivity in Ωcm R = ohms reading obtained on Model 4620/4630 Example 1: For measurement performed in soil with a high limestone content, the reading is R = 225Ω, with A = 300cm (3m). ρ = 2π x 225Ω x 300cm ρ = 423,900Ωcm Digital Ground Resistance Tester Model 4620 and 4630... - Page 37 Model 4630 as shown in Figure 19. Proceed as follows: • Remove the shorting link between X and Xv • Connect all four auxiliary ground electrodes Example 3: If the reading is R = 15: ρ (resistivity) = 2π x R x A A (distance between electrodes) = 450 cm ρ = 6.28 x 15 x 450 = 42,390Ωcm Ω Figure 19 Digital Ground Resistance Tester Model 4620 and 4630...
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Page 38: How To Use 25 Ω Calibration Checker (Accessory)
Figure 20 How to Use 25Ω Calibration Checker (optional accessory) The calibration checker is good for both the 4620 and 4630. It has a resistance of 25Ω. The procedure to use the calibration checker is as follows: • Loosen the X, Xv, Y and Z terminals. • Insert the calibration checker as shown in Figure 21. -
Page 39: Maintenance
Please make sure that you have already read and fully understand the WARN- ING section on page 3. • To avoid electrical shock, do not attempt to perform any servicing unless you are qualified to do so. • To avoid electrical shock and/or damage to the instrument, do not get water or other foreign agents into the case. • Turn the instrument OFF and disconnect the unit from all circuits before opening the case. • Use specified spare parts only. Disassembly Necessary equipment: • A Torx ACX.10 screwdriver or similar • A Phillips screwdriver With the Phillips screwdriver, remove the 4 screws (1) at the back of the case and free the internal unit (2) from the yellow case (3). Digital Ground Resistance Tester Model 4620 and 4630... -
Page 40: Power Supply
To free the display board from the cover: • Remove the 3 Phillips screws and unsolder all the wires connect- ing to the terminals and to the fuse. To free the power supply board from the bottom of the body: • Remove the 6 Phillips screws at the back of the body and discon- nect the connector coming from the battery. Power Supply 6.3.1 Testing the Battery • Short-circuit the X and Z terminals. • Press the “TEST” button. • If the low battery or charge indicator lights up on the display you will need to replace or recharge the batteries. Digital Ground Resistance Tester Model 4620 and 4630... -
Page 41: Replacing The Battery (Model 4620)
NiCd or NiMH of the same size): • Remove the plug under the batteries. • Set the switch to the position: NiCd/NiMH • Replace the plug. • Insert the 8 rechargeable cells. NOTE: The Model 4620 does not have a built-in battery charger. The rechargeable cells will need to be charged outside the instrument. 6.3.3 Recharging the Battery (Model 4630) • Connect the battery charge connector to the mains. • The CHARGE indicator light will turn red. -
Page 42: Replacing The Safety Fuse
• Use a soft cloth lightly dampened with soapy water. • Rinse with a damp cloth and then dry with a dry cloth. • Do not use alcohol, solvents or hydrocarbons. Storage If the Model 4620 is not used for a long period of time (two months or more), remove the batteries and store them separately. If the Model 4630 is not used for a long period of time (two months or more), it is recommended to charge the battery for a few hours. -
Page 43: Repair And Calibration
NOTE: You must obtain a CSA# before returning any instrument. 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 e-mail our technical support team: 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 E-mail: techsupport@aemc.com www.aemc.com NOTE: Do not ship Instruments to our Foxborough, MA address. Digital Ground Resistance Tester Model 4620 and 4630... -
Page 44: Limited Warranty
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. Full warranty coverage and product registration is available on our website at www.aemc.com/warranty.html. -
Page 45: Digital Ground Resistance Tester Model 4620 And
Notes: Digital Ground Resistance Tester Model 4620 and 4630... - Page 48 10/16 99-MAN 100259 v18 Chauvin Arnoux , Inc. d.b.a. AEMC Instruments ® ® 15 Faraday Drive • Dover, NH 03820 USA • Phone: (603) 749-6434 • Fax: (603) 742-2346 www.aemc.com...