Instruction Manual - Cole
Contents
1. Part Number 6111 218 must be used 16 17 18 Megger Limited 4271 Bronze Way Dallas Texas Archcliffe Road Dover 75237 1088 USA Kent CT17 9EN England T 1 800 723 2861 T 0 1 304 502101 T 1214 333 3201 F 0 1 304 207342 F 1214 331 7399 Megger OTHER TECHNICAL SALES OFFICES Megger Megger Z A Du Buisson de la Couldre 23 rue Eugene Henaff 78190 TRAPPES France T 33 1 30 16 08 90 F 33 1 34 61 23 77 Toronto CANADA Sydney AUSTRALIA Madrid SPAIN Mumbai India and the Kingdom of BAHRAIN Megger products are distributed in 146 countries worldwide This instrument is manufactured in the United Kingdom The company reserves the right to change the speci Megger is a registered trademark Part No 6172 660 V03 Printed in England 1103 www megger com ation or design without prior notice2. cable appearing endless Open or short circuits will reflect all the pulse and a large reflection will be displayed At an open or short circuit all the transmitted energy is reflected and the CFL510F will not see the cable beyond that fault As a pulse travels down a cable the size and shape of that pulse is gradually attenuated by the cable The pulse reduces in amplitude and becomes more elongated or stretched The level of attenuation or losses is determined by the cable type the condition of the cable and any connections along its length The limit of how far you can see is determined by the point beyond which you will not be able to see or distinguish a reflection To help identify small reflections especially at greater distance the CFL510F has an adjustable gain setting By increasing the gain small reflections become more obvious The CFL510F can be used on any cable consisting of at least two insulated metallic elements one of which may be the armouring or screen of the cable The CFL510F has internal matching networks to allow testing of 25 50 75 and 100 cables These typically correspond to power coaxial data and data telecoms cable By selecting the CFL510F impedance closest to that of the cable under test maximum power can be transmitted into the cable allowing long cables to be tested The velocity factor of the CFL510F must be adjusted to match that of the cable under test allowing an accurate distan
3. need to take and could prevent damage to yourself and the instrument The CFL510F is an advanced instrument capable of identifying a wide range of cable faults The instrument uses a technique called Pulse Echo also known as Time Domain Reflectometry or TDR A pulse is launched into a cable from one end This can be on either a pair of conductors or a conductor and the screen The pulse travels down the cable at a velocity determined by the insulation between the conductors and this resistance to the flow of the pulse is characterised as impedance for the cable Any changes in cable impedance will cause a proportion of the pulse to be reflected The pulse velocity is normally described as a fraction of the speed of light and is called the Velocity Factor By measuring the time between the transmitted pulse and the reception of the reflected pulse and multiplying this by the speed of light and the velocity factor the actual distance to the reflection point can be established Reflections are caused by changes in the cables characteristic impedance such as poor joints or discontinuities Faults showing an impedance higher 4 than that of the cables normal impedance will cause a reflection of the same polarity i e positive whilst faults with an impedance lower than that of the cable will cause an inverse negative going reflection Matched cable terminations absorb all the pulse hence no end of cable reflection will occur the
4. to set the correct values Refer also to Velocity factor later in this text Connection to Cable Under Test Connect the test lead to the cable under test Connection may be made to a live system with a voltage to earth ground less than 300V with an installation over voltage category of III or lower This means that the instrument may be connected to any fixed wiring of a building installation but not to primary supply circuits such as overhead cables A Fused Lead Set must be used to connect to energised live systems Refer to the accessories section for options When selecting 25 cable impedance an internal 50Hz 60Hz filter is automatically switched in Measuring distance to fault Ensure that the whole length of the cable can be seen on the display and that the range selected is correct Find key The Find key searches for the furthest major change of impedance This may be a fault or the end of the cable if this is a short or open circuit When found the event is displayed and the cursor placed on the leading edge The gain zoom and cursor position may need to be adjusted for accurate measurement Note that Find does not adjust the TxNull or Velocity Factor To enable difficult to see faults to be identified the gain of the instrument can be adjusted With the gain at minimum small changes of cable impedance may be overlooked By increasing the gain the fault becomes more obvious If no faults are obvi
5. F have been arranged such that the instrument is easy to learn and use The instrument controls consist of the following Instrument Display The display shows the user the current settings of the instrument and the reflected energy trace from the cable connected PER Transmission pulse gl Reflection mawa Eu 0 TS Gain Range Distance to cursor Impedance Tx Null This rotary control allows the user to match the internal balance circuit of the CLF510F to that of the cable under test When correctly adjusted the majority of the displayed transmitted pulse can be nulled out allowing cable features close to the start of the cable to be identified Refer to section TX Null for further details Cursor Left Moves the distance cursor to the left Auto repeats if held down VA Cursor Right Moves the distance cursor to the right Auto repeats if held down USER CONTROLS AND DISPLAY O Find key Automatically moves the cursor to the first potential fault change of impedance Power Pressing this button will turn the instrument on or off depending on its current state Range A bi directional button allowing range adjustment from 10m 30ft to 3km 10 O00ft in 6 steps The bi directional feature allows ranges to be selected forward and backward without having to scroll through all the ranges in one direction Gain This control is used to increase or decrease the gain of the instrumen
6. Megger CFL510F Cable Fault Locator USER MANUAL ASAFETY WARNINGS Although this tester does not generate any hazardous voltages circuits to which it can be connected could be dangerous due to electric shock hazard or due to arcing initiated by short circuit While every effort has been made by the manufacturer to reduce the hazard the user must assume responsibility for ensuring his or her own safety For use on energised systems rated up to 300 V Installation Category HI the fused clip set Megger Part Number 6111 218 must be used Relates to the transient over voltages likely to be met in fixed wiring installations 4mm plug to BNC Adaptor This 4mm plug to BNC adapter is intended for use with telecomm network cables only it is not designed or intended for direct connection to an energised mains supply However in normal use it may be subject to telecom network voltages TNV as defined by IEC 60950 3rd edition 1999 04 The BNC plug and socket are by necessity accessible The outer sheath for this connector is normally at SELV levels however under single fault conditions it may carry hazardous voltages The operator must therefore verify that the accessible plug or socket is at SELV levels prior to touching or alternatively wear appropriate insulated gloves m The instrument should not be used if any part of it is damaged m Test leads probes and crocodile clips must be in good order clean and with no broken or crac
7. air agent Cleaning the instrument should only be done by wiping with a clean cloth dampened with soapy water or Isopropyl Alcohol IPA 13 OPERATION Except where otherwise stated this specification applies at an ambient temperature of 20C General Ranges 10m 30m 100m 300m 1000m 3000m 30ft 100ft 300ft 1000ft 3000ft 10000ft Accuracy 1 of range pixel at 0 67VF Note The measurement accuracy is for the indicated cursor position only and is conditional on the velocity factor being correct Resolution 1 of range nput Protection This instrument complies with IEC61010 1 for connection to live systems up to 300V CAT III Fused leads must be used if the voltage between the terminals exceeds 300V 14 Output pulse 5 volts peak to peak into open circuit Pulse widths determined by range and cable impedance 250 500 750 1000 10m 7ns 7ns 7ns 7ns 30m 20ns 20ns 20ns 20ns 100m 100ns 60ns 100ns 100ns 300m 300ns 120ns 170ns 300ns 1000m 1000ns 520ns 680ns 1000ns 3000m 3000ns 2020ns 2340ns 3000ns Gain Set for each range with four user selectable steps Variable from 0 01 to 0 99 in steps of 0 01 Velocity Factor Impedance matching 25 50 75 100 Tx Null 0 to 120 Selectable from the menu Once per second or three times a second Refresh Rate Automatic after 5 minutes with no key press Power Down SPECIFICATIONS Backlight Stays on for 1 minute when activated C
8. ase Dimensions Batteries Six LR6 AA type batteries Manganese alkali or nickel cadmium or nickel metal hydride cells Instrument weight Nominal voltage Case material 9V for Alkali or 7 2V for NiCad Connectors Battery consumption 100mA nominal 140mA with backlight Test Lead 20 30 hours continuous use depending on backlight use Safety This instrument complies with IEC61010 1 Display for connection to live systems up to 300V CAT II Fused leads must be used if the voltage between the terminals exceeds 300V Environmental EMC Complies with Electromagnetic Compatibility Specifications Light industrial BS EN 61326 1 with a minimum performance of B for all immunity tests Mechanical The instrument is designed for use indoors or outdoors and is rated to IP54 230 mm long 9 inches 115 mm wide 4 5 inches 48 mm deep 2 inches 0 6kg 1 32lbs ABS Two 4mm safety terminals 2 metres long consisting of 2 x 4mm shrouded connector to miniature crocodile clips 128 64 pixel Graphics LCD Operational Temperature 15C to 50C 5F to 122F Storage Temperature 20C to 70C 4F to158F 15 ORDERING INFORMATION CFL510F Included Accessories Test amp Carry case with strap 6420 125 Miniature Clip Test Lead Set 6231 652 User Guide 6172 659 Optional Accessories Fused prod and clip set 6111 218 For use on energised systems rated up to 300V CATIN use the fused prod and clip set Megger
9. ce measurement to be read directly from the instrument Where the VF of a cable is not known but the length is the cursor can be set to the end of the cable and the VF on the CFL510F adjusted until the correct cable length is displayed Other configuration settings include changing the distance units between metres and feet changing the propagation velocity units between a ratio and a distance per microsecond Display contrast is fully adjustable to compensate for all viewing conditions A backlight aids viewing in low ambient light conditions The instrument can be powered by manganese alkali nickel cadmium or nickel metal hydride batteries All cells must be of the same type BATTERY FITTING AND REPLACEMENT When the low battery symbol d_ appears in the display window the cells are nearly exhausted and should be replaced as soon as possible Use alkaline cells IEC LR6 AA 1 5V or 1 2V rechargeable cells only To install or replace the cells switch the instrument off Disconnect the test leads loosen the battery cover retaining screws and remove the cover Lift out and disconnect the battery holder Replace the cells ensuring that correct polarity is observed shown on the battery holder Incorrect battery cell polarity can cause electrolyte leakage resulting in damage to the instrument Refitting the battery holder is the reverse of removing it USER CONTROLS AND DISPLAY The controls of the CFL510
10. displayed The Units in which the distance to To select a function use the GAIN key to scroll up or down the menu To change the units us the LEFT or RIGHT cursor keys Options m metres or ft feet VF Format CFL510F velocity factor the cable under test which should be adjusted to match RATIO m us or ft us Impedance Output impedance of the CFL510F 25 50 75 100 Test Rate Refresh rate 1 second or 3 second 11 OPERATION TX Null Without the TX Null control the transmitted pulse would be visible at the beginning of the trace swamping any reflections within the pulse length the dead zone The TX Null circuit matches the characteristic impedance of the cable under test to produce an equivalent pulse Subtracting this equivalent pulse from the transmitted pulse effectively removes the dead zone from the display and allows near end reflections to be seen NOTE In some cases it may not be possible to completely null the transmitted pulse Unbalanced Balance edusted 12 Velocity Factor The velocity factor is used by the instrument to convert the measured time for a pulse to be reflected into a distance It can be displayed as a ratio of the speed of light eg 0 660 66 of the speed of light or as a distance per microsecond in ft us or m us If the exact length of cable is known and the reflection from the cable end is visible then an accurate vel
11. ked insulation a Check that all lead connections are correct before making a test a A Fused Lead Set must be used to connect to energised live systems Refer to the accessories section for options m Disconnect the test leads before accessing the battery compartment a Refer to operating instructions for further explanation and precautions m Safety Warnings and Precautions must be read and understood before the instrument is used They must be observed during use NOTE THE INSTRUMENTS MUST ONLY BE USED BY SUITABLY TRAINED AND COMPETENT PERSONS CONTENTS Asafety Warnings 3 Introduction 5 General description Battery replacement User Controls and Display 8 Operation Layout and functions 10 General Testing procedure Line Feed Connection to cable under test Measuring distance to fault Menu TX Null Velocity Factor Pulse widths Techniques to improve accuracy Care and Maintenance 15 Specifications 16 Symbols used on the instrument are A A CE Caution Refer to accompanying notes Equipment protected throughout by double or reinforced insulation Instrument flash tested to 3 7kV rms Equipment complies with current EU directives INTRODUCTION Thank you for purchasing the CFL510F cable fault locator Before attempting use of your new instrument please take the time to read this user guide ultimately this will save you time advise you of any precautions you
12. ocity factor can be determined m Locate the reflection caused by the end of the known length of cable with the instrument set on the shortest possible range to see the end of the cable Locate the start of this reflection as described in the Operation section of this manual a Adjust the velocity factor until the correct cable ength is shown m Note the VF value for future reference The measurement of the distance to the fault can now be made with more confidence The ability of the instrument to accurately measure the distance to a cable feature relies on the velocity factor being correct Any errors in the velocity factor are directly related to distance measurement errors OPERATION Pulse Widths As the RANGE and IMPEDANCE matching of the CFL510F are adjusted so the duration of the transmitted pulse changes The pulse widths range from 7ns to 3ps to overcome signal attenuation and enable the instrument to see further down a length of cable The greater the range selected on the CFL510F the wider the transmitted pulse The accuracy of the Distance to fault is not affected by the length of the pulse However if two or more features exist close together excluding open or short circuits then the second or subsequent feature may be partially masked by the reflection from the first fault Hence for potential multiple features the instrument should be used with the shortest suitable range and so the smalle
13. ous adjust the gain until any major reflections appear Open and short circuits should easily be identified Partial faults can be less obvious If no significant reflections can be seen use the TX Null to minimise the effect of the output pulse on any potential near end faults refer to section on TX Null OPERATION In the event of no reflections being visible increase gain until any reflection can be easily identified If no reflections can be seen try shorting or earthing the far end of the cable to ensure that you are seeing the whole length of the cable The cursor can also be moved using the LEFT and RIGHT cursor keys Move the cursor to the beginning of the reflection The distance to the fault can then be directly read from the display NOTE The distance calculation is performed using the velocity factor set in the CFL510F If this velocity factor is not correct for the circuit under test the displayed distance will be incorrect Opposite are shown two typical trace displays The top shows an open circuit at 2000m away the second a short circuit at 2000m away 10 OPERATION Instrument Features Menu The Menu key allows the user to change the units of measurement for Distance Velocity factor Impedance and Test Rate By pressing the Menu key the CFL510F will display Distance Unit VF Format Impedance Test rate Available options Description Distance Unit fault is
14. st pulse width that can see both features For output pulse characteristics refer to output pulse data in the CFL510F Specification at the end of this guide Techniques To improve on the accuracy of the measurement numerous techniques can be used depending on the situation encountered Not every situation can be described but the following points are effective and the most common and easily implemented methods Test the cable from both ends When fault finding a cable it is good practice to take measurements from both ends Particularly in the case of open circuit faults when the true end of the cable is not visible If the measurement is made from both ends then the combined answer should equal the expected length of the cable Even when the true end of the cable is visible on the display the reflections after the fault may be too obscure to analyse clearly In this case measurement from both ends yields a clearer picture as well as improved accuracy It is also good practice to follow the cable route with a cable tracer as not all cable runs will be straight It can save a great deal of time if the exact route of the cable is known as faults are often found at these points and can be accredited to third party intervention Care and Maintenance Other than replacing the batteries the instrument has no user serviceable parts In case of failure it should be returned to your supplier or an approved Megger Limited rep
15. t This helps the user identify faults over the entire cable length Velocity Factor Adjusts the Velocity Factor VF of the instrument to match that of the cable under test IMPORTANT The VF value must match the VF of the cable under test to give an accurate distance measurement Menu Allows the user to change the units of measurement for Distance Velocity Factor Impedance and Test Rate Refer to menu section later in this text Backlight Pressing this button will toggle the backlight on and off The backlight will automatically switch off after 1 minute the display contrast to suit local ambient Contrast Allows the user to manually correct lighting conditions Output Sockets 4mm shrouded sockets designed to accept the leads supplied with the instrument Battery cover Located on the back of the instrument and provides the user with access to the battery compartment The cover must not be removed while the instrument is switched on or connected to a cable The instrument must not be operated with the cover open OPERATION General Testing procedure Ensure the correct test leads are firmly fitted into the sockets of the instrument Switch on the instrument The CFL510F will display the start screen for a couple of seconds followed by a trace The instrument will be set to the range and velocity factor last used If these settings are different for the cable under test C U T then use the RANGE and VF keys
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