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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1

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

3

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

4

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.

5

The controls of the TDR have been arranged such that the
instrument is easy to use. The instrument controls consist of
the following:

1) L1 Sockets:

The sockets are designed to accept the leads supplied with the
instrument, or the optional mains blocking filter. Line 1 is

usually connected to the faulty line or the line under test. In
Xtalk mode, this is the transmitting terminal.

2) Contrast:

This is a rotary control that lets the user correct the display
contrast for user preference and adjust for the extremes of
temperature.

3) Balance:

This is a rotary control that allows the user to match the
impedance of the internal balance circuit to that of the cable
under test. When balanced, the transmitted pulse can be nulled
out and cable features close to the leads can be detected.

4) L2 Sockets:

The sockets are designed to accept the leads supplied with the
instrument, or the optional mains blocking filter. They allow a
second cable to be tested simultaneously for direct comparison
or are used on a known good line to null out the transmitted
pulse instead of using the internal balance circuit. In Xtalk
mode, this is the receiving terminal.

5) Instrument Display:

The display shows the user the current settings of the
instrument and the reflected energy trace from the cable(s)
connected. It can also display the menu and help screens and
stored traces.

6) Cursor Left:

This control moves the cursor left or, if in a menu screen,
selects a lower value.

Features and Controls

6

1 2 3 4

5

7

11
1716

14 15

18

9 10

6 8

12 13

7) Range / Configuration:

Pressing this button changes the instrument range to the next
lower range. If this button and the shift key are pressed
together then the CONFIG menu is invoked.

8) Cursor Right:

This control moves the cursor right or, if in a menu screen,
selects a higher value.

9) Power:

Pressing this button will turn the instrument on or off depending
on the current state.

10) Velocity factor:

This control is a bi-directional switch and can be used to
increase or decrease the velocity factor. When in a menu
screen it will also navigate up and down the screen.

11) Mode:

This control cycles round the display modes, L1 only, L1 and
L2, L1 - L2 and Xtalk.

12) Gain:

This control is a bi-directional switch and can be used to
increase or decrease the gain of the instrument in 6dB steps
from 0dB to 90dB. When in a menu screen it will also navigate
up and down the screen.

13) Backlight:

Pressing this button will toggle the backlight on and off.

14) Print / PC:

Pressing this key sends the current screen to an attached
EPSON compatible printer as a screen dump. If pressed with
the shift key then the instrument will go to computer controlled
operation where a computer running the appropriate download
program can upload / download saved traces and also change
the instruments language.

15 Display / Diff:

This key changes the display from the entire range
to a zoomed in view, or if pressed with the shift key
changes the TDR from dual trace mode to difference mode.

16) Mem / Save:

This key allows access to the save and recall of traces.
Pressing the key with the shift key allows the trace to be saved.
Pressing it without the shift key allows a saved trace to be
recalled.

17) Shift:

Pressing this key in conjunction with another will result in an
alternate function, it the key is dual purpose.

18) Help:

Pressing this key toggles the instrument in and out of help
mode. In help mode, the instrument will display key sensitive
help information.

Battery cover:This is on the back of the instrument and
provides the user with access to the batteries. The cover must
not be removed while the instrument is on or connected to a
cable. The instrument must not be operated with the cover
open.

7

Ensure the test leads are firmly fitted into the sockets of the
instrument. Ensure the cable(s) under test is (are) de-energised
before connecting the test leads. If working on live power
cables, a blocking filter(s) must be used to isolate the
instrument from the live line(s).

Switch the instrument on and the instrument will display the
start screen for a couple of seconds. The TDR will then display
a trace. The instrument will have powered up, set to the last
used mode, range and velocity factor. If the settings are
different for the cable under test (C.U.T) then first use the mode
key to cycle through the available modes and select the
required one. Next, use the VF bi-directional key to set the
velocity factor for the C.U.T. (If this is unknown then follow the
steps detailed in the Velocity Factor section.) Finally, cycle
through the available ranges until you select a range long
enough to see the whole cable length of the C.U.T.

With the gain set at the lowest level required to easily identify
the cable feature, e.g. an open or closed circuit, move the
cursor to the very beginning of the reflection. To locate the start
of the reflection more accurately, press the DISPLAY key to
zoom in around the current cursor position. The cursor is now
fixed and using the cursor left and cursor right keys, the trace
will move relative to that point. The current zoom location with
respect to the whole trace range is shown at the top of the
display. The distance is then directly read from the display. The
distance calculation is performed using the current velocity
factor. If this velocity factor is not correct, the displayed
distance will be incorrect.

To enable partial cable faults to be identified, i.e. those faults
that only reflect part of the signal back to the instrument, the

gain of the instrument can be adjusted. With the gain at the
minimum required to see the end of the cable on the trace, if a
minor fault is suspected then increase the gain until the fault is
more visible.

Below are shown two typical trace displays. The top one is an
open circuit cable, the open circuit at 1200m away, the second
is a short circuit at 1200m away and the instrument is
displaying the low battery warning.

Operation

8

Balance Control

Without Balance Control (see point 3 in the User Controls and
Display section) the transmitted pulse would be visible at the
beginning of the trace, swamping any reflections within the
pulse length (the dead zone). The balancing circuit attempts to
match 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
and allows cable features much closer in to be detected.
Alternatively, using the [L1-L2] & [OFF] mode, where L2 is
connected to a known good length of the cable under test, L2 is
used instead of the balancing circuit to automatically null the
transmitted pulse.

NOTE: In many cases, it will be impossible to completely null

the transmitted pulse.

Velocity Factor

The velocity factor is the scalar that is used to convert the
measured time interval into an actual length of cable. It can be
displayed in one of two ways: a ratio of the transmitted pulse
speed to the speed of light, or as a distance per microsecond.
When it is displayed as the distance per µs (either m/µs or
ft/µs) the velocity factor will be indicated as half the speed of
the pulse in the cable. This is because the pulse in fact has to
go along the cable to the cable feature and back again which is
twice the distance to the feature.

The table of velocity factors in the HELP pages of the
instrument is a rough guide and in practice, the settings are

subject to many variable factors. If the exact length of a piece
of cable of the same type as the C.U.T is known and the
reflection from the cable end is visible then a more accurate
value can be determined:

1. 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.

2. Locate the start of this reflection as described in the

Operation section of this manual.

3. Adjust the velocity factor until the correct cable length is
shown.

The measurement of the distance to the fault can now be made
with more confidence that the measurement will be correct. The
ability of the instrument to accurately measure the distance to a
cable feature relies on the velocity factor being correct, any
percentage errors in the velocity factor are directly proportional
to distance measurement errors. Hence, the TDR2000 uses the
velocity factor to three decimal places to reduce any errors.

Pulse Widths

The TDR2000 pulse widths range from 20ns to 16µs to
overcome signal attenuation and enable the instrument to see
further down a length of cable. In distance terms for the size of
the transmitted pulse, this represents a transmitted pulse from
as small as 4.0m to 3199m! (This assumes a velocity factor of

0.667.) Without Balance Control, this would be an enormous

dead zone, but with the instrument correctly balanced, faults
can be seen well within the pulse width.

9

Instrument Features:

As the measured distance is taken at the start of the reflected
pulse, the size of the pulse width does not affect the accuracy
of the measurement. However, if the first feature does not give
a complete reflection such that the instrument can see beyond
it to a second feature, the ability to discern between features is
affected by the pulse widths. If there are multiple features, the
instrument can only fully discern between them if the features
are more than the pulse width apart. Hence, for discerning
multiple features, the instrument should be used with the
smallest pulse width that can see both features.

When using the RANGE key to change the instrument’s range,
the pulse widths are set to the instrument’s default for that
range. If the attenuation of the C.U.T is too high or there are
multiple cable features which the default pulse width can not
discern between, the user can override the default by entering
the CONFIG Options menu.

Memory Features

The TDR2000 has 15 memory locations, which can be used to
store traces from previously tested cables. These may be
stored for future analysis or be downloaded to the
TRACEMASTER software for analysis on a PC. Each memory
location stores the graphical trace along with the gain, range
and mode settings. With the TRACEMASTER software, the
stored trace can be annotated and kept on file for future
reference. You can also upload a trace to the instrument using
the TRACEMASTER software, including the first 64 characters
of any annotation applied to that trace.

With the extensive dual trace and difference modes available to
the TDR2000, memory locations can be used as comparisons
for live traces. This is useful if the known good cores that would
normally be used in the [L1]-[L2] mode are two far away from
the C.U.T. Instead, a memory trace of a known good cable can
be compared against the C.U.T.

10

CONFIGURATION MENU

There are two configuration menus - options and setup. The Options menu includes all those settings that will be adjusted in the
everyday use of the instrument. The Setup menu includes those settings that are more for the user preferences and calibration and
will only be accessed occasionally. The top line of both menus is the Configuration Menu setting that allows the user to toggle
between the Options and Setup menus.

Trace 1 & 2: This option determines which waveforms will be acquired for display as traces 1&2. Though the MODE key can
select between the four basic modes of operation (see the introduction), the user has more ability to select modes of operation and
can allocate a memory trace to either trace 1 or 2. Trace 1 can be set to L1, L2, L1-L2, Xtalk and any memory trace M1-M15. Trace
2 can be set to L2 and any memory trace M1-M15.

11

CONFIGURATION - OPTIONS

CONFIG MENU [OPTIONS]

TRACE 1 [L1]

TRACE 2 [L2

PULSE WIDTHS [200Ns]

DISTANCE UNITS [m]

AVERAGING [x1]

UNIT RANGE [200m]

CONFIGURATION - SETUP

CONFIG MENU [SETUP]

VF DISPLAY [RATIO]

ZERO POINT (nS) [20]

POWER DOWN (mins) [5]

BACKLIGHT OFF (mins) [2]

LANGUAGE [1]

PRINTER DELAY (mS) [05]

Pulse Widths: This option allows the user to override the

default pulse width set by the instrument for a
particular range and select an alternative
pulse width available within the range. (See
the Specification section for the table of pulse
widths and the section under Instrument
Features for more details.)

Distance Units: This option allows the user to select whether

the cursor distance will be displayed in
metres, feet or nano-seconds.

Averaging: When trying to locate cable features when a

high gain is required, any noise on the C.U.T
will be amplified as well as the reflected
pulse. This noise may make accurate location
of the cable feature more difficult. To
overcome this, the TDR2000 has the ability to
have averaging where the cable is over­sampled and any random noise should be
greatly reduced. This option allows this to be
set at 1x, 2x, 3x or 4x over-sampling.

Note: A high over-sample rate can reduce

the battery lifetime.

VF Display: The velocity factor can be displayed as a
ratio

of pulse speed to the speed of light or as a
distance per microsecond. This option selects
the display type. Please refer to the

Instrument Feature section for more details.

Zero Point: This setting enables the zero point of the

instrument to be set at the end of the test
leads, so the test lead length is automatically
deducted from any distance calculation. The
nominal zero point setting for the standard
test leads is 20ns, however to zero non
standard test leads please take the following
steps:

1. From the Config Menu - Options set the Range to a
range suitable for the test leads.

2. Set the Distance Units to nS.

3. From the Config Menu - Setup set the Zero Point to 0.

4. Press the MODE key to exit the Config menu and
display a trace.

5. Measure the distance (in nS) to the ends of the test
leads, to identify this open circuit and close circuit the
lead end.

6. In the Config Menu - Setup set the Zero Point to this
measured time.

All measured distances will now be shown relative to the end of
the test leads.

Power down: This allows the user to set the power down to

5, 10 or 15 minutes after the last key press.

12

Backlight off: This allows the user to set the backlight auto

turn off to 1, 2 or 5 minutes.

Language: This allows the user to select either language

1 or 2. Language 1 is always English but
language 2 is set by which language the user
uploads to the instrument with the
TRACEMASTER software.

Printer Delay: The serial port on this instrument is fully

opto-isolated as part of the over-voltage
category protection. As a result there is no
hardware handshaking available, so to allow
a line printer to keep up with the instrument
a variable delay set by this setting is added
between each block of data sent to the
printer.

Techniques to improve accuracy

To improve on the accuracy of the measurement, numerous
methods 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 test the cable
from both ends. Particularly in the case of open circuit faults,
the true end of the cable is not visible, Thus it is harder to
estimate whether the answer obtained is realistic. If the
measurement is made from both ends, then the combined
answer should add up to the expected length of the cable.

Even in the case when the true end of the cable is still visible,
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
will usually be found at points were human intervention has
occurred, junction boxes, splices, recent ground excavation etc.

Care and Maintenance

Other than replacing the batteries, the instrument has no user
serviceable parts. In the event of failure if should be returned to
your supplier or an approved AVO repair agent.
Cleaning the instrument should only be done by wiping with a
clean cloth dampened with soapy water or Isopropyl Alcohol
(IPA).

13

Except where otherwise stated, this specification applies at an
ambient temperature of 20°C.

Ranges: 50m, 100m, 200m, 400m,

1km, 2km, 4km, 8km, 16km.

Resolution: 0.1m up to 200m

0.2m up to 400m

0.1% of range above 400m

Measurement Accuracy: 0.1% of Range

[Note – The measurement accuracy is for the indicated cursor
position only and is conditional on the velocity factor being
correct.]

Input Protection: The inputs will withstand 150Vdc or

150Vac up to 500Hz.

Output pulse: 14 volts peak to peak into open

circuit, 7 volts peak to peak
into 120Ω

Pulse width user selectable:

50m range: 20ns, 40ns, 60ns, 80ns, 100ns
100m range: 20ns, 50ns, 800ns, 100ns, 140ns
200m ranges: 20ns, 60ns, 100ns, 140ns, 200ns
400m range: 40ns, 80ns, 160ns, 200ns, 400ns
1km range: 80ns, 160ns, 260ns, 500ns, 1µs
2km range: 160ns, 260ns, 500ns, 1µs, 2µs
4km range: 250ns, 500ns, 1µs, 2µs, 4µ s
8km range: 500ns, 1µs, 2µs, 4µ s, 8µ s
16km range: 1µ s, 2µs, 4µ s, 8µ s, 16µ s

Gain: 0 to 90dB in steps of 6dB
Velocity Factor: Variable from 0.300 to 0.999 in steps

of 0.001

Repetition rate: Burst of 256 pulses every 1 or 10

seconds.

Output impedance: Balanced 120Ω
Balance Adjustment: 0Ω to 120Ω
Update Rate: Once per second.
Power Down: Automatic after 5, 10 or 15 minutes

with no key press, user selectable.

Backlight: Stays on for 1, 2 or 5 minutes when

activated, user selectable.

Specification

14

Communications Port: RS-232C compatible

1 start bit, 8 data bits, 1 stop bit and
no parity, 9 600 baud standard

Batteries:

Eight LR6 (AA) type batteries, manganese-alkali or nickel­cadmium or nickel-metal-hydride cells.

Nominal voltage: 12V for Alkali or 9.6V for NiCad and NiMH.
Low battery warning occurs at 9.4V (alkali) and 8.56V

(rechargeable).
Battery consumption 150mA nominal, 240mA with backlight

(10/20 hours continuous use depending on backlight
dependency)

Safety:

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.

EMC:

Complies with Electromagnetic Compatibility Specifications
(Light industrial)
BS/EN50081-1-1992
BS/EN50082-1-1992

Mechanical

The instrument is designed for use indoors or outdoors and is
rated to IP54.

Case Dimensions: 250 mm long

200 mm wide
110 mm deep

Instrument weight: 1.5kg (3.3lbs)
Case material: ABS
Connectors: Two pairs of 4mm safety terminals.

9 way D-type connector for serial
communication.

Display: 256 x 128 pixel Graphics LCD.

Environmental

Operational Temperature: -15°C to +50°C (5°F to 122°F)
Storage Temperature: -20°C to 70°C (-4°F to158°F)
Operational Humidity: 95% at 40°C (104°F)

Included Accessories

Test and carry Pouch 6420-114
Miniature Clip Test Lead Set 6231-654
Carry Strap for Pouch 6220-611
User Guide 6172-446

OptionalAccessories

Blocking Filter 6220-669

15

The instrument contains static sensitive devices, and care must
be taken in handling the printed circuit board. If an instrument’s
protection has been impaired it should not be used, but sent for
repair by suitably trained and qualified personnel.

The protection is likely to be impaired if for example; it shows
visible damage; fails to perform the intended measurements;
has been subjected to prolonged storage under unfavourable
conditions, or has been subjected to severe transport stresses.

NEW INSTRUMENTS ARE GUARANTEED FOR 3 YEARS

FROM THE DATE OF PURCHASE BY THE USER.

NOTE: Any unauthorized prior repair or adjustment will
automatically invalidate the Warranty.

INSTRUMENT REPAIR AND SPARE PARTS

For service requirements for MEGGER Instruments contact:

AVO INTERNATIONAL or AVO INTERNATIONAL

Archcliffe Road Valley Forge Corporate Centre
Dover 2621 Van Buren Avenue
Kent, CT17 9EN. Norristown, PA19403
England. U.S.A.

Tel: [phone] Tel: [phone]
Fax: [phone] Fax: [phone]

For sales Contact: MeterCenter [phone] www.MeterCenter.com

Approved Repair Companies

A number of independent instrument repair companies have
been authorised for repair work on most MEGGER instruments,
using genuine MEGGER spare parts. Consult the Appointed
Distributor/Agent regarding spare parts, repair facilities, and
advice on the best course of action to take.

Returning an Instrument for Repair

If returning an instrument to the manufacturer for repair, it
should be sent freight pre-paid to the appropriate address. A
copy of the invoice and of the packing note should be sent
simultaneously by airmail to expedite clearance through
Customs. Arepair estimate showing freight return and other
charges will be submitted to the sender, if required, before work
on the instrument commences.

Repair and Warranty

16