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Metrotech 480B SFL 2Dx, Руководство по эксплуатации

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24

5 

   PRINCIPLES OF OPERATION 

 

5.1 Functional Theory 

Even an experienced user needs to review the basics of sheath fault locating before 
proceeding.  This will improve the changes of finding the fault and save valuable time.  
Comparing electrical current to water flowing through a pipe applies extremely well to fault 
locating.  Trying to find a leak in a water pipe, you might seal off one end, pump water into 
the other, and look for water to appear near the leak.  The principles of sheath fault locating 
are identical.  The cable equivalent of sealing off the pipe is to lift all connections at both 
ends of the cable, creating a high resistance open condition.  The “water” in this case is the 
current flowing through the cable towards the fault.  We look for the current “leak” with an 
A-Frame” 
 
Both ends of the cable must be disconnected from ground. 
 
The SFL Transmitter applies a low frequency signal (4.8 Hz) between and isolated conductor 
with an earth fault and another ground point.  This induces a signal into the ground from the 
fault location.  This signal pattern is detected by the A-Frame Receiver contact probes. 
 
A typical hookup for locating a sheath fault, also called a shield-to-earth fault, is illustrated in 

Figure 5-1

. 

 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 

Содержание 480B SFL 2Dx

Страница 1: ...A 95054 Nashville TN 37217 Dr Herbert Iann St 6 800 446 3392 800 624 6210 96148 Baunach Germany 408 734 1400 Direct 615 366 7323 Direct 49 9544 680 408 734 1415 Fax 615 360 9855 Fax 49 9544 2273 Fax www metrotech com nashville metrotech com service sebakmt com sales metrotech com Warranty One year Specifications Subject to change without notice ISO 9001 2000 Certified Copyright 2008 All Rights Res...

Страница 2: ...uidelines of ISO 9001 and ensures quality in its design development production installation and servicing disciplines Metrotech Corporation 2005 2008 Metrotech Corporation 3251 Olcott Street Santa Clara CA 95054 USA Tel 1 800 446 3392 1 408 734 1400 Fax 1 408 734 1415 E mail sales metrotech com Internet www metrotech com Revision B November 2008 ...

Страница 3: ...eatures 23 5 Principles of Operation 24 5 1 Functional Theory 24 5 1 1 Earth Voltage Gradient 26 5 1 2 Equipotentials 26 5 1 3 Multiple Fault Patterns 28 5 1 4 Distortion Due to Adjacent Conductors 28 6 Checkout Procedure 29 7 Operation 31 7 1 Check the Batteries Prior to Going into the Field 31 7 2 Ensure all conductors are de energized 31 7 3 Lift the Grounds 31 7 4 Attach the Transmitter to the...

Страница 4: ...39 9 1 1 Peak Method 41 9 1 2 Null Method 41 9 2 Inductive Coupling with Metroclamp 42 9 3 Inductive Indirect method 43 9 4 480B 50 60Hz Power Line Locating 44 9 5 Estimating the Depth of a Conductor 45 9 6 4810 Probe for Pinpointing and Depth Estimation 46 9 7 Using a Second Metroclamp for Conductor Identification 47 8 6 Multiple Faults 37 10 Maintenance 48 10 1 Receiver Battery Replacement 48 10...

Страница 5: ...d Ground Point 26 Figure 5 3 Multiple Fault Signal Patterns 28 Figure 6 1 Checkout Test Set Up 29 Figure 7 1 Synchronizing the A frame 32 Figure 7 2 Fault Confirmation 33 Figure 8 1 Perpendicular Method 35 Figure 8 2 Triangulation Method 36 Figure 8 3 Locating an Equipotential Circle 36 Figure 8 4 Fault Location Using Extension Cable for Increased Sensitivity 37 Figure 9 1 Direct Conductive Connec...

Страница 6: ...gth and Reference LCD s on the A Frame for judging proximity to faults comparing multiple faults and detecting pinholes and trees in power cable Detection of low and high resistance faults Automatic battery checking and low battery warning Non polarized A Frame Single handed operation No need to carry locator receiver as well as A frame Operation of the unit is completely automatic there are no op...

Страница 7: ... local utility company or other owner of the plant before entering an access area or connecting a Metrotech transmitter 3 Before connecting transmitter directly to any conductor make sure that the line is de energized and out of service Never make a direct connection to a live power cable 4 Before connecting the transmitter directly to any conductor make sure the operating ground black cable is co...

Страница 8: ...ill result 4 Attach transmitter to conductor Check Fault Resistance 1 Turn Transmitter OFF 2 Plug Black and Red leads into the Transmitter 3 Stretch Black lead 180 degrees away from conductor 4 Push grounding rod into earth and clamp black lead to grounding rod Establish the best ground possible See figure 3 2 5 Clamp Red lead to target conductor sheath See Figure 3 3 6 Turn transmitter power knob...

Страница 9: ...6 Figure 3 2 Clamping Black Lead to Ground Rod Figure 3 3 Clamping Red Lead to Conductor ...

Страница 10: ...etected by the Receiver The reading will vary from locate to locate according to utility type and conditions and how close the Receiver is to the targeted utility 3 Locate Line Follow your target utility sweeping left and right as you walk away from the Transmitter The Receiver displays the highest reading when it is directly over the target conductor Adjust the gain level to see a high reading ov...

Страница 11: ...is about 2 steps away from the ground rod and the spike with the white band is in line with the targeted cable The A frame receiver must be placed as shown in figure 3 5 for synchronization and for unit to operate correctly Push the A Frame spikes into the ground Switch the Receiver ON wait until arrow flashes Figure 3 5 Positioning of A Frame Receiver for Synchronization White Band Black Band LCD...

Страница 12: ...ed off The Reference number indicates the potential gradient associated with the fault at the synchronization location 5 The Active number will be displayed at the same time as the Reference number but it will change when the A frame spikes are pulled out The Active number will decrease when you move away from the synchronization location and will increase as you get closer to the fault on the cab...

Страница 13: ...10 Figure 3 6 Locating the Cable Fault with A Frame Receiver ...

Страница 14: ...feet until the arrow changes direction again 5 Move the A Frame across the cable until a slight movement causes the arrow to change direction The fault is located at the center of the A Frame 6 Check entire cable for multiple faults If more faults are present check the Active number at each fault site and compare it to the Reference number The higher the Active number the larger the fault If you h...

Страница 15: ...reception Which can be determined by turning to the locating equipment off and on We suggest the user try to eliminate the interference by one or more of the following measures Reorient or relocate the receiving antenna Move the equipment away from the Receiver Plug the equipment into an outlet on a circuit different from that to which the Receiver powered If necessary the user should consult the ...

Страница 16: ...pment included is the following Part Model Description Remarks 11206 4 8Hz 83 kHz Transmitter 400D108 83 kHz 50 60 Hz Receiver 10498 4 8Hz A Frame Receiver 400A140 Conductive attachment 10873 Vehicle Mount Charger 12 Volts DC power lead for Transmitter 11207 Operating Manual ...

Страница 17: ...gure 4 1 Standard Equipment Standard Equipment 1 480B SFL Transmitter 2 480B Receiver 3 Conductive Attachment 4 Ground Rod 5 Vehicle Mount 12 Volt DC Power Lead 6 Operation Manual 7 Bracket 8 SFL2Dx A Frame ...

Страница 18: ... the 480B SFL2 Sheath Fault Locator are listed below Part Model Description Remarks 4290 2 MetroClamp For Inductive Coupling 4490 4 MetroClamp For Inductive Coupling 400A132 100 Ground Lead Extension SON830 Small Sonde SONH83K High Power Sonde 4810 Inductive probe ...

Страница 19: ...Fault and Line Locate mode Fault Metering Continuous fault resistance monitoring 0 to 5M Ohm Nominal Output Power Inductive Mode 1watts across the loop Conductive Mode 125 watts across 2 7kOhm Fault and Line Locate Mode 1 75 watts across 10K Battery Type Rechargeable Battery Life Induce 70 hours Line only locate 55 hours Fault and Line Locate 10 hours Battery Check Automatic in the Fault Line Loca...

Страница 20: ...cates signal level each bar 6dB Numerical LCD Active Displays potential gradient to pinpoint and differentiate multiple faults Reference Displays maximum potential gradient at synchronization location and can be compared to Active number for pinpointing major fault Battery 9 V NEDA 1604 or equivalent Battery Life 100 hours continuous use Battery Test Automatic at power on Weight 4 4 lb 2 0 kg Dime...

Страница 21: ...ceiver Frequencies Active 83kHz Passive 50 60Hz Battery Type Six size C Alkaline Cells Battery Life 250 hrs average Headphone Impedance 2K ohms usable at 100 ohms and up Dimensions 11 63 L x 9 H x 3 13 D 29 5 cm x 23 cm x 8 cm Weight 4 5 lb 1 9 kg ...

Страница 22: ...al shock will result See Figure 4 2 for location of Transmitter controls and indicators described below Figure 4 2 Transmitter Control Panel 1 External Charging LED 2 Locate Power LED 3 LCD Display 4 SFL Conductive Attachment Output Jack 5 High Voltage LED 6 Selector Knob ON OFF and Locate method 7 Clamp and standard conductive attachment output Jack 8 Charge Jack 1 2 3 4 5 6 7 8 ...

Страница 23: ...ention of connecting the black cable to the grounding spike and the black lead to the back input Connect the red cable to the sheath under test and the red lead to the red input Failure to do so will cause the A frame to point toward the ground spike and away from the fault HIGH VOLTAGE LED The high voltage LED super RED will flash when the Mode Switch is set to the Fault Line Locate Mode The flas...

Страница 24: ...s TWO types of information BATTERY STATUS First 3 seconds the amount of Transmitter battery charge is indicated by the number of bars illuminated CIRCUIT RESISTANCE The number of bars indicate in ohms the amount of signal resistance on your conductor and your faulted cable ...

Страница 25: ...he bar graph will display the direction to the fault and the number of bars displayed reflect the magnitude of the fault Active The Active LCD will display in numbers the potential gradient at points along the cable with a maximum value at the greatest fault Reference The Reference LCD will remember the potential gradient at the synchronization location Figure 4 3 A Frame Controls and Indicators B...

Страница 26: ...hes 10 hours of battery life Figure 4 4 Battery Status Indication 4 7 2 Battery Access Plate Located on the underside of Receiver control panel Remove the two thumbscrews to release the plate See Figure 9 1 4 7 3 Conductive Pads The A Frame Receiver is shipped with two protective foam pads with large washers attached to the Receiver probes These pads are used for tracing on dry hard surfaces Prote...

Страница 27: ...tical The cable equivalent of sealing off the pipe is to lift all connections at both ends of the cable creating a high resistance open condition The water in this case is the current flowing through the cable towards the fault We look for the current leak with an A Frame Both ends of the cable must be disconnected from ground The SFL Transmitter applies a low frequency signal 4 8 Hz between and i...

Страница 28: ...25 Figure 5 1 Typical SFL 2 Transmitter Connection 1 Black Lead 2 Red Lead 3 Ground Rod 4 Fault 5 Faulty conductor open on both ends 1 2 3 4 5 ...

Страница 29: ...e LCD display indicates the relative distance to the fault and it is size 5 1 1 Earth Voltage Gradient Note in Figure 5 2 that the gradient pattern appears to be concentric circles near the fault Properly interpreting this pattern is the key to successful operation of the 480BSFL unit 5 1 2 Equipotentials The circles shown in Figure 5 2 represent lines of equal voltage The boxes show what the bar ...

Страница 30: ...turn toward the Transmitter the zero point was a fault As you continue they will increase until you reach the fault Nearly 70 of the signal exists within the last 1 3 of the distance between the ground spike and the fault The amount of signal measured and displayed by the A Frame is proportional to the number of field lines in Figure 5 2 between the A Frame spikes Thus the maximum signal point occ...

Страница 31: ...g the procedure described in Section 7 7 We recommend that multiple faults be attacked one at a time i e whenever a fault is positively located it should be repaired before looking for the other faults F1 F2 Figure 5 3 Multiple Fault Signal Patterns 5 1 4 Distortion Due to Adjacent Conductors Whenever an un insulated adjacent conductor lies between a fault and the ground return point the return cu...

Страница 32: ...CD will display the battery charge status If the indicator does not show at least 5 replace or recharge the batteries Turn the Transmitter OFF Turn the A Frame Receiver ON The Active and Reference LCD display will show a battery indication Each number represents the hours of battery life If the BA 10 appears replace the battery 1 ea 9 volt 2 Connect the Test Cables Connect the test cables to the e...

Страница 33: ...the transmitter Mode switch to FAULT LINE LOCATE Look at the battery level for battery condition 5 Synchronize the Receiver Hold the A Frame so the black spike is closest to the ground connection Push the A Frame into the ground 6 Push the Receiver On Off Switch to ON The A Frame Receiver will repeat the battery test After the battery test the arrow facing the simulated fault red test clamp flashe...

Страница 34: ...ult CAUTION Do not place a shorting bar across external Output Jacks or connect the two leads together Damage to the Transmitter may result 7 4 Attach the Transmitter to the conductor and check the fault resistance 1 Turn the Transmitter OFF 2 Plug the Black and Red leads into the Transmitter 3 Clamp Red lead to target conductor sheath Make sure the red clamp does not make contact with any leaves ...

Страница 35: ...ault At the ground rod the black A Frame spike must be nearest the ground rod At a fault the white A Frame spike must be nearest the fault 1 Hold the A Frame so the black spike is closest to the ground rod 2 Push the A Frame spikes into the ground 3 Switch the Receiver ON Wait until the arrow flashes 4 If the arrow points away from the ground spike there is a fault 5 If the arrow points towards th...

Страница 36: ...33 Figure 7 2 Fault Confirmation ...

Страница 37: ... good physical ground connection is needed to receive strong signal 4 When the arrow changes direction back track Check the Active number and compare it to the Reference number If both Active and Reference numbers have the same or similar value you have found the major fault 5 Insert the A Frame every two feet until the arrow changes direction again then turn it 90 degrees Check for obvious causes...

Страница 38: ...d the A Frame parallel to the cable path As you move away from the ground rod the bar graph and the Active number will gradually decrease until reaching the midpoint It will then increase until reaching the fault When the A Frame center passes a line perpendicular to the sheath fault the directional arrow indicators will rapidly change positions and the bar graph and Active number will drop to zer...

Страница 39: ...Surface Cable Fault Figure 8 2 Triangulation Method To find an equipotential circle see Figure 8 3 insert the A Frame into the ground and pivot around one spike Rotate the A Frame back and forth until the exact point is found where the flashing arrows change direction The A Frame is now on an equipotential circle and is perpendicular to the fault By marking this line and repeating the process with...

Страница 40: ...rtionally reduced This condition can lead to problems if the signal levels are reduced to the point that they can no longer be detected by the A Frame Whenever working with weak signals due to long distance faults or other reasons increased sensitivity can be obtained by extending the distance between the A Frame spikes using the extension cable This extension method can be applied to any of the p...

Страница 41: ... the ground point The higher the impedance of the fault the closer you must be to detect it For Example If the A Frame only reliably points away from the ground connection within 10 feet then the A frame will only detect the fault within about 10 feet Outside this distance the signal is too weak to reliably detect For this reason we highly recommend tracing and marking the line before searching ou...

Страница 42: ... are described below 9 1 Direct Conductive Connection This is the preferred mode of operation because the Transmitter is connected directly to a metallic part of the conductor hydrant meter riser valves sheath tracer wire allowing a strong maximum signal to reach the conductor In this operating mode the Receiver can be closer to the Transmitter and adjacent buried conductor interference is reduced...

Страница 43: ... As you move farther away from the Transmitter you will need to increase the sensitivity It is important to tune the sensitivity as low as possible in order to sharpen the reception and reduce signal bleed off onto adjacent conductors 7 Set the Receiver RANGE knob to NORM adjusting to HIGH when necessary 8 When starting a locate you need to pre locate the targeted conductor by using the broad rang...

Страница 44: ...ll increase as you approach the location of the conductor See Figure 9 2 Figure 9 2 Peak 480B Receiver Response 9 1 2 NULL METHOD To pinpoint the location of the conductor use the NULL method by holding the 480BB Receiver in a flat horizontal position The audio tone will increase and then go silent at the exact location of the conductor See Figure 9 3 Figure 9 3 Null 480B Receiver Response ...

Страница 45: ...possible but you can position a Metroclamp around the conductor you want to trace The Inductive Coupling method uses the 4820 Metroclamp to induce a signal onto the conductor when direct metallic contact is not possible The clamp is placed around the target conductor The Transmitter then induces a signal through the clamp When using the Metroclamp the conductor must be well grounded i e with sheat...

Страница 46: ...signal through the antenna mounted on the transmitter case No ground connection is needed when a signal is induced onto the target conductor SAFETY WARNING Do not operate the Transmitter in the Inductive Mode while it is resting on or near a metal surface or large metal object Incorrect test readings and damage to the transmitter may result 1 Position the transmitter over the buried conductor maki...

Страница 47: ...SITIVITY to SEY If no current is present you will be unable to adjust to SET 4 Hold the Receiver in an upright vertical position with the face of the Receiver facing you and at right angles to the targeted conductor 5 Move the Receiver from side to side over the targeted conductor location until you obtain the maximum PEAK response For better signal reception hold the Receiver close to the ground ...

Страница 48: ...ctor See Figure 4 5 Figure 9 5 Estimating the Depth of a Conductor 3 When you locate the conductor a second time with the Receiver at a 45 degree angle mark the spot on the ground The distance between this second spot and the true location of the conductor A less the distance between the center of the Receiver and the ground B is equal to the depth of the conductor C See Figure 9 5 4 Measurement a...

Страница 49: ...eiver 3 Turn the 480B Receiver SENSITIVITY all the way up and turn the RANGE to HIGH The thumb knob on the 4810 Probe will then control the 480B Receiver sensitivity 4 Turn the 480B Receiver MODE SWITCH to ACTIVE 5 Adjust the 4810 Inductive Probe SENSITIVITY as needed keeping it as low as possible to sharpen the Receiver response 6 Use the same triangulation procedure as described in Section 4 5 E...

Страница 50: ... Metroclamp cable into the jack marked AUX INPUT on the Receiver 3 Set the RANGE switch on the receiver to Norm Set the MODE switch to Active 4 Place the Metroclamp around each conductor in succession making sure that the jaws are fully closed The conductor with the highest field strength indication is the target conductor Figure 9 7 Note This method will work only if there is no cross bonding on ...

Страница 51: ...rse procedure for installing new battery Connector Figure 10 1 A frame Receiver Battery Replacement 10 2 480B Receiver Battery Replacement Open the BATTERY ACCESS door on the front of the unit Extract the battery holder and replace batteries positioning according to the indications shown inside the battery holder Close the battery access panel ensuring that there are no wires caught between the re...

Страница 52: ...t Service Center 1824 Murfreesboro Road Suite 104 Nashville TN 37217 Telephone 800 624 6210 615 366 7323 Fax 615 360 9855 E mail Nashville metrotech com European Service Center Seba Dynatronic Mess Und Ortungs technick GmbH Dr Herbert Iann Str 6 D 96148 Baunach Germany Telephone 49 9544 680 Fax 49 9544 2273 E mail service sebakmt com Internet www sebakmt com Or call the factory for the nearest aut...

Страница 53: ..._______ Gas oil petroleum or other gaseous materials Yellow _______________________________________________ Sewers storm and sanitary drain lines Green _______________________________________________ Water irrigation or slurry lines Blue Note If you have any questions regarding marking requirements or procedures in the United States please call you local One Call Center International customers ple...

Страница 54: ...merchantability and fitness for a particular purpose Metrotech shall not be liable for errors contained herein nor for incidental or consequential damages from the furnishing of this information This manual contains proprietary information that is protected by copyright All rights are reserved No part of this manual may be photo copied reproduced magnetically stored transmitted or translated into ...

Страница 55: ...ther than those approved by Metrotech Warranty does not include batteries Expendable items such as fuses and lamps are excluded Any detection product proved defective under this warranty will be repaired or replaced free or charge at the Metrotech Corporation factory or approved Metrotech repair station The equipment should be returned to our factory by prepaid transportation after requesting and ...

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