Megger TDR2000 User Manual

User Guide

MEGGER

®

Time Domain Reflectometer
MEGGER

®

CFL535E - TDR2000

Advanced Test Equipment Rentals

www.atecorp.com 800-404-ATEC (2832)

®

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Safety Warnings 3
Introduction 4
Features and Controls 6
Operation 8
Instrument Features 9

Balance Control 9
Velocity Factor 9
Pulse Widths 9
Memory Features 10
Configuration Menu 11
Techniques to Improve Accuracy 13
Care and Maintenance 13

Specification 14
Repair and Warranty 16

MeterCenter [phone] www.MeterCenter.com

Caution: Refer to accompanying
notes.

Equipment protected throughout by
double or reinforced insulation

Instrument flash tested to 3.7kV
r.m.s. for 1 min.

Equipment complies with current EU
directives

Symbols used on the instrument are:

Contents

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SAFETY WARNINGS

★ This instrument meets the safety requirements of IEC 61010 part 1 to 150V cat III. If it is to be used in

situations where hazardous live voltages may be encountered then an additional blocking filter must be
used.

★ CAUTION (Risk of electric shock)
★ 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.

★ The instrument should not be used if any part of it is damaged.
★ Test leads, probes and crocodile clips must be in good order, clean and with no broken or cracked insulation.
★ Check that all lead connections are correct before making a test.
★ Disconnect the test leads before accessing the battery compartment.
★ Refer to operating instructions for further explanation and precautions.
★ Safety Warnings and Precautions must be read and understood before the instrument is used. They must

be observed during use.

NOTE

THE INSTRUMENT MUST ONLY BE USED BY SUITABLY TRAINED AND COMPETENT PERSONS

Thank you for purchasing this quality AVO product. Before
using 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.

Your TDR2000 is a very advanced instrument capable of
identifying a wide range of cable faults. The instrument uses a
technique called Time Domain Reflectometry (TDR) which in
many ways is similar to radar. Narrow pulses of electrical
energy are transmitted along a pair of conductors in a cable.
The pulse travels through the cable at a velocity determined by
the insulation between the conductors and the resistance to the
flow of the pulse is characterised as impedance for the cable.
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 given.

Faulty cables, poor joints or discontinuities will all cause a
change in impedance. Impedance’s higher than the cable’s
cause a normal reflection. Impedance’s lower than the cable’s
cause an inverse reflection. Matched terminations absorb all the
pulse hence no reflection will occur, the cable appearing
endless. Open or Short circuits will reflect all the pulse energy
and the TDR will not ‘see’ the cable beyond that fault.

As a pulse is transmitted down a cable, the size and shape of
that pulse is gradually attenuated by losses in the cable: the
pulse gets smaller in height and more spread out. The level of
attenuation 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 discern a reflection. To maximise the instruments range, the
TDR2000 has an adjustable gain setting on its input that can
apply up to 90dB of gain to the reflected signal to allow you to
discern a reflection from farther away. By combining this
variable gain with increasing pulse widths, the TDR2000 can
discern faults up to 16Km away.

The MEGGER TDR2000 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 balancing circuit,
which is described in the Operating Instructions, can balance
for any cable with a characteristic impedance of 0-120Ω. Dual
inputs and the large graphic display allow a wide range of
comparative tests to be performed between cable pairs or
stored results. The instrument has 15 trace memories, enabling
previous test results to be displayed and compared with “live”
results. This allows the gradual ageing of a cable to be
monitored or characteristic changes to be detected between
periodic tests, for example if the cable has suffered water
ingress or has been tapped and split.

Introduction

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There are four modes of operation to get “live” results, and
these are:

[L1] & [OFF] Trace is acquired from L1 only, internal

balance circuit used.

[L1] & [L2] Traces are acquired from L1 & L2 for

comparison, internal balance circuit used.

The

DIFF key selects whether both are displayed
or the difference between them is displayed.

[L1-L2] & [OFF] The displayed trace is the difference between

L1 & L2, L2 acts as the balance circuit for L1.

[Xtalk] & [OFF] A pulse is transmitted on L1 and any

reflection is looked for on L2, only L2 is
displayed.

A setup disk changes the stored language via the serial link,
and various user options can be tailored via the CONFIG menu
on the instrument. The download feature allows transfer of the
waveform data to a computer, for analysis and storage for
future reference. Other setting options 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. Abacklight aids viewing in low
ambient light conditions. Should use of the instrument prove
difficult then on screen, key sensitive help is available.

The batteries to power the instrument are housed in the
compartment on the case back, the cover is held in place with
two screws. The batteries are held in a carrier, which hold the
batteries securely, and allow rechargeable battery packs to be
quickly changed. The instrument can be powered by
manganese-alkali, nickel-cadmium or nickel-metal-hydride
batteries. All cells must be of the same type.

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