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- Full autoranging for measuring the length
of power, telephony, CATV and LAN
cables, provides distance to an open or
short.
- Extra large, high resolution backlit LCD.
- Automatic output impedance control of
25, 50, 75, 100, 125 or 150 ohms.
- User-friendly menu on screen operation.
- Cable length calibration function.
- Internal library of 39 standard cable
types.
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The Megger TDR900 is an advanced instrument capable of
measuring cable lengths and finding distance to an open
or a short using Time Domain Reflectometry. It offers
exceptional features and a range capability normally
associated with far more expensive instruments. The
measurement range spans from 15 feet (5 m) to 10,000 feet
(3 km) with a minimum resolution of 20 inches (50 cm).
The TDR900 can be used for any cable consisting of at
least two insulated metallic elements, one of which may
be the sheath or shield of the cable. The Meter has
automatic internal matching networks to allow testing of
25, 50, 75, 100, 125, or 150 Ohmscables. (These
correspond to power, telephony, CATV, and LAN cables.)
The Meter can be closely matched to the cable under test
using the menu selection keys. The propagation velocity
value can be similarly adjusted to match the cable under
test; thus ensuring an accurate distance measurement.
The other user adjustable setting is changing the distance
measurement units (feet or meters).
The Meter is housed in a rugged ABS enclosure which is
dust and weatherproof to IP 42. The unit also comes with a
soft carrying case and an alligator clip adapter. It is
powered by 4 AA (NEDA 15A or NR 6) batteries, which
are stored in a compartment on the back of the Meter.
The batteries are held in a carrier for quick and easy
replacement. |
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APPLICATIONS
Telephony
Installation and Repair technicians desire a portable test set
for testing service drops and inside wiring during trouble
ticket dispatches. The TDR900 connects to service drops or
inside wiring and determines single or multiple cases of
trouble to the customers’ services. The Meter detects and
displays cable issues, which do not meet the provider’s
facility criteria during the maintenance process. The
TDR900 displays test results including: open, short, voltage
detection and distance to fault in feet (meters). A tone
generator is also built into the Meter for pair identification
and tracing.
Construction and Maintenance technicians can benefit
greatly from an easy-to-use test set capable of testing OSP
cabling systems. The TDR900’s exceptional measurement
range accommodates testing in the subscriber network.
Contractors/Installers
The TDR900 fills various applications ranging from cable
verification and fault location, panel mapping to cable
stock control. The Meter supports either electrical
contractors or telecom/datacom contractors.
Contractors can verify cable lengths on buried service
drops before billing service providers.
Electric Power
Street Lighting: To install street lighting, short lengths of
cable run from lamppost to lamppost. It is important that
joints are accessible as the cable runs underground. The
TDR900 is used initially to ensure there is enough cable on
the drum to give a continuous run and then utilized to
check the installation is correct.
Mining
Due to Ex ‘d’ (Explosion proof) regulations most countries
do not allow TDRs down mines, however, as the mine
deepens, shafts are dug from the surface and umbilical
cables are dropped down. These carry power for the tools
and telecommunication needs. Due to the distances
involved, these cables especially the telecom, become
stretched and are likely to fail. The TDR900 can easily be
justified as a maintenance tool to check cable integrity.
Broadcasting
Outside broadcasting: Outside broadcast vehicles carry
an enormous amount of cables depending on the situation,
e.g. sporting events can use ten or more different camera
locations. Due to the temporary nature of the installation,
cables get damaged and a low cost, simple to read TDR
can easily be justified to quickly locate failures.
Studio Broadcasting: Cameras in a studio have a trailing
group of cables, which are dragged around the floor, as
the cameras move. This puts a strain both on the cable
and in the joints, as quality of the signal is very important.
Aerials: The signals from broadcasting companies are
transmitted through aerials and large drops of cable are
used due to the height of these aerials. The cables
become stretched especially around the joints, giving poor
service.
Stocktaking
A simple application is stocktaking. Any company that
purchases reasonable amounts of cable or any company
that produces cable needs to know how much they are
buying or have on the shelf. Traditional graphic TDRs
have had limited success in this area due to cost and
waveform interpretations. The TDR900 provides both
simplicity and accuracy.
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- CE-Certificated
- Accurate to 20 inches (50 cm) throughout the entire
range
- Extra-large backlit (ICON type 7 segment) LCD
- Automatic output impedance control, auto-range, autozero,
and auto-sensitivity allows for closely matching to
a wide range of cables under test. Only V.O.P (velocity
of propagation) settings required.
- Displays cable length if the cable’s V.O.P (velocity of
propagation) is known or displays V.O.P (velocity of
propagation) if a cable’s length is known.
- 20 internal memory locations store up to 20 custom
cable V.O.P settings.
- n Internal library of 39 standard cables allow for quick and
easy measurements for industry standard cable types.
- Tone Generator (oscillating 910 to 1100 Hz; 5 V peak to
peak) for cable identification and tracing.
- Line Voltage Detection: Displays “OUCH” message and
stops operation if line voltage exceeds 6.5 V.
- Safety Protection (up to 250 V RMS)
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| Cable Length Measurements |
| Ranges: |
12,000 ft (3.7 km)@ V. O. P 99.9
9,800 ft (3.0 km)@ V. O. P 80.0
8,000 ft (2.4 km)@ V. O. P 66.0
6,200 ft (1.9 km)@ V. O. P 50.0 |
| Accuracy: |
± 2 % of reading + 20 inch (50 < 300 ft (100 m)
± 2 % of reading > 300 ft (100 m)
* This accuracy is effective for Coaxial Cables up to 8,000 feet,
Telephony Cables up to 6,000 feet, and Structured Wiring up to
3,000 ft. |
| Resolution: |
20 inches (50 cm) |
| V.O.P (Velocity of Propagation): |
Adjustable from 1.0 % to 99.9
(in 0.1 % step) |
| Cable Length Calibration Function |
| Allows you to measure the V.O.P, given as a percentage of the
speed of light, of a known cable length.
Required minimum length of sample cable: 30 ft (10 m) |
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