Megger TDR500/3, CFL510G Operating Manual

TDR1000/3 TDR1000/3P CFL510G TDR500/3

Time Domain Reflectometers

User Manual

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CONTENTS

Introduction ...........................................................................................................................................................................................................5

Overview.................................................................................................................................................................................................................7

Instrument layout and display .......................................................................................................................................................................7

Controls...................................................................................................................................................................................................................9

Rotary switch....................................................................................................................................................................................................9

Range and cursor control.............................................................................................................................................................................10

Backlight and hold.........................................................................................................................................................................................11

Setup................................................................................................................................................................................................................12

Operation..............................................................................................................................................................................................................13

General testing procedure............................................................................................................................................................................13

Operating modes ...........................................................................................................................................................................................13

Connection to cable under test ...................................................................................................................................................................14

Velocity factor................................................................................................................................................................................................16

Pulse widths....................................................................................................................................................................................................17

Techniques............................................................................................................................................................................................................18

Test the cable from both ends.....................................................................................................................................................................18

Care and maintenance.........................................................................................................................................................................................18

Battery ...................................................................................................................................................................................................................19

Battery replacement.......................................................................................................................................................................................19

Battery indicator ............................................................................................................................................................................................20

Specifications........................................................................................................................................................................................................21

Waste electrical and electronic equipment.......................................................................................................................................................23

Test Lead selection..............................................................................................................................................................................................25

Repair and warranty ............................................................................................................................................................................................26

Megger contact information ..............................................................................................................................................................................29

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G SAFETY WARNINGS

■ Safety warnings and precautions must be read and understood before the instrument is used. All Safety warnings and

precautions must be observed during use.

■ The circuit under test must be switched off, de-energised, securely isolated and proved safe before test connections are

made.

■ Use the correct lead set. On power systems the Megger fused lead set must be used. Refer to the Test Lead selection page

in this user guide to identify the correct lead set.

■ The operator must verify that the circuit is safe before testing and take the appropriate precautions.

■ Ensure that hands remain behind guards of probes/clips when testing.

■ The instrument should not be used if any part of it is damaged. Also all test leads, probes and crocodile clips must be in

good order, clean and with no broken or cracked insulation.

■ Disconnect the test leads before removing the battery cover. The battery cover must be in place whilst conducting tests.

■ This product contains no user service parts.

■ All relevant safety procedures must be followed.

THE INSTRUMENT MUST ONLY BE USED BY SUITABLY

TRAINED AND COMPETENT PERSONS

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Symbols

The following symbols are used on this instrument

CAUTION: RISK OF DANGER

EQUIPMENT PROTECTED THROUGHOUT BY DOUBLE INSULATION OR REINFORCED

INSULATION

EQUIPMENT COMPLIES WITH RELEVANT EU DIRECTIVES

EQUIPMENT COMPLIES WITH AUSTRALIAN EMC REQUIREMENTS (C-tick) (NOT FOR SAFETY)

THIS EQUIPMENT SHOULD BE RECYCLED AS ELECTRONIC WASTE

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Introduction

Thank you for purchasing this 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 need to take and could prevent damage to yourself and the instrument.

This 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 cable’s construction will determine its characteristic impedance and the velocity a pulse travels down the cable.

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 cable’s characteristic impedance, such as poor joints or discontinuities. Faults showing impedance higher than that of the cables normal impedance will cause a reflection of the same polarity, i.e. positive, while faults with impedance lower than that of the cable will cause a negative going reflection. Matched cable terminations absorb all the pulse hence no “end of cable” reflection will occur, the 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 TDR 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 loss) 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 instrument has an adjustable gain setting. By increasing the gain small reflections become visible

The velocity factor of the TDR must be adjusted to match that of the cable under test, allowing an accurate distance 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 TDR adjusted until the correct cable length is displayed.

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The instrument can be used on any cable consisting of at least two separate conductive elements, one of which may be the armouring or screen of the cable. It has internal matching networks to allow testing of 25 Ω, 50 Ω, 75 Ω and 100 Ω cables. (These typically correspond to power, coaxial data and data/telecoms cable). By selecting the TDR impedance closest to that of the cable under test, maximum power can be transmitted into the cable allowing long cables to be tested. If the impedance of the cable under test is unknown, the auto-impedance function may be used to determine the cable impedance and set-up the TDR automatically.

The distance units can be changed between metres and feet. Display contrast is automatically adjusted for temperature, but can be adjusted further for optimum display. A backlight aids viewing in low ambient light conditions.

The instrument can be powered by manganese alkali, or nickel-metal-hydride battery. All cells must be of the same type.

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Overview

Hold key

Four Way Joy Switch

Rotary Switch

Backlight

Backlit

Left & Right Arrows

There is an audible tone on key

Instrument Layout & Display

presses. A low tone means the key is invalid

256 x 128

dot matrix display

used in setup

Mainly controls range and cursor

Turn to OFF to switch the instrument off. Turn to any other position to turn the instrument on

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Display

Range

Velocity Factor

Impedance

Battery

Distance Between

Cursor 2

Cursor 1 Cursor 2

Position

Cursor 1

Hold Indicator

State Indication

Position

Cursor 1 & 2

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Controls

Auto

Setup

*Cursor 2

*Cursor 1

*where fitted

Rotary Switch

Turn the switch from OFF to another position to turn the instrument on. The instrument may be turned off, by switching to OFF, or the instrument may switch itself off if it has not been used for 5 minutes or the battery is exhausted.

The other selections are

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