Megger TDR900 User manual

T
ime Domain Reflectometer
Megger TDR900
USER’S
MANUAL
© Copyright 2003 Fine Instruments Corp. All right reserved.
Specifications subject to change without notice.
Litho in Korea.
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Basic Specifications
Maximum Range : Depends upon the V.O.P of the cables under test.
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 %
Range Selection : Automatic range control
Resolution : 20 inches (50 cm)
Accuracy : ± 2 % of reading + 20 inches (50 cm) < 300 ft
(100 m)
± 2 % of reading > 300 ft (100 m)
This accuracy i s effective for C oaxial Cables up to 8,000 ft, Telephony
Cab l es up to 6,000 ft, and Structured Wiring up to 3,000 ft.
Output Impedance : 25, 50, 75, 100, 125 or 150 ohms
Impedance Selection : Automatic output impedance control
Velocity Factor : Adjustable from 1.0 % to 99.9 %
Tone Generator : Oscillating 810 - 1100 Hz (5 V
p-p
unloaded)
Cable Library : 39 standard cable types
Memory Location : 20 for custom cable types
Connector : BNC
Input Protection : 250 V RMS
Line Voltage Detection : 6.5 V
SOURCES LIKE SMALL HAND-HELD RADIO
TR ANSCEIVERS, FIXED STA TION RA DIO
AND TELEVISION TRANSMITTERS, VEHICLE
RA DIO TR ANSM ITTERS AND CEL LUL AR
PHONES GENERATE ELECT ROMAGNETIC
RADIATION THAT MAY INDUCE VOLTAGES
IN THE TEST LEADS OF THE MULTIMETER.
IN SU CH CASES THE ACCURA CY OF T HE
MULT IMETER C ANNO T BE GUARAN TEED
DUE TO PHYSICAL REASONS.
WARNING!
Warning
The product should not be connected to any energized
circuits. Connection to mains supply voltages will damage
the Meter and could be hazardous to the user.
The product contains parts that can be damaged by static
disc harge. Disc harge the c able to be te st ed be fore
connecting the product to the cable.
Read “Safety Information” before using this Meter.
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1. Safety Information 3
2. The TDR Cable Length Meter 4
3. Controls, Indicators, and Buttons Overview 5
4. Meter Operation 8
4.1 Principles of operation 8
4.2 How to connect a cable to the Meter 8
4.3 How to set the cable type 9
4.3.1 Selecting a library cable type 9
4.3.2 Cable library for 39 standard cable types 10
4.3.3 Testing cables not included in library 12
4.4 How to determine unknown V.O.P settings 14
4.4.1 Expanding cable library
for custom cable types using nonvolatile memory 15
4.5 How to measure cable length 19
4.6 How to check networks (Thin Ethernet) 19
5. Changing the measurement scale between English and Metric 20
6. Measurement accuracy 21
7. Theoretical and actual V.O.P 22
8. Special features 23
8.1 Low battery indication 23
8.2 Overrange indication 23
8.3 Enable or disable the auto-power-off mode 24
8.4 Tone Generator mode 25
8.5 Line Voltage Detection mode 25
9. Maintenance 26
10. Specifications 27
Repair and Warranty
CONTENTS
Safety Warnings
This Me ter c omplies with the safety requiremen t s of IEC 1010-1 : 2001. I t is
designed for use on de-energized circui t s only, however this Meter is protec t ed
against telephone networking voltages (EN 60950 : 1999 Sec. 2.3). Connection to
any mains supply voltages may result in damage to the Meter and/or a hazard to
the user. Hence the user must assume responsibility for ensuring his or her own
safety.
International Symbols used on the Meter
Caution! Refer to the explanation in this manual.
Double insulation or Reinforced insulation
Battery
Meter complies with current EU Directives.
International Standards
Safety : IEC 1010-1 : 2001
EMC : EN 61326 : 1997
+
A 1 : 1998
1. Safety Information
EMC Standard Category of Pass
ESD IEC 1000-4-2 A
EM IEC 1000-4-3 A
Burst IEC 1000-4-4 A
Surge IEC 1000-4-5 A
Conducted RF IEC 1000-4-6 A
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The Meter is a handheld and battery operated instrument capable of measuring
cable lengths and finding distance to an open or a short using TDR(Time Domain
Reflectometry) techniques, given access to one end only.
The Meter 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 cables, which correspond to power, telephony, CATV, and LAN,
etc. cables.
The Meter can be closely matched to the cable under test using the menu selection
keys. The V.O.P(Velocity of Propagation) value can be similarly adjusted to match
the cable under test; thus ensuring an accurate distance measurement.
The Meter incorporates an oscillating tone generator, tha t is detectable with a
standard tone probe (not supplied) available in t he marke t places, for use in the
tracing and identification of pairs within a cable .
The Meter displays “ ” message and stops operation i f line vol t age of the cable
under test exceeds 6.5 V when the Meter is t urned on. The B NC terminal is
protected up to 250 V RMS in order to prevent it from being demaged by its
misconnection to live circuits of networking.
You can s tore up to 20 cable test results for custom cable types in internal
nonvolatile memory and the stored cable library provides quick and easy access to
39 standard c able types, which enables accurate measurement without the
necessity of entering V.O.P (Velocity of Propagation).
The on-site measurement scale changing feature enables the Meter to be globally
used for both Metric measurement and English measurement without changing the
measurement scale at factory.
The Meter comes with an Alligator Clip adaptor, a user’s manual and a soft carrying
case.
2. The TDR Cable Length Meter
A lthough this manual describes the operation of the Meter for bo t h Metric
measurement and English measurement, all illustrations and examples assume use
of the Meter for English measurement.
(1)
(3)
(4)
(7)
(5)
(6)
(2)
3. Controls, Indicators, and Buttons Overview
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(3) MENU (on screen) SELECTION BUTTONS
Each setting of the Meter to a measurement function may activate one or more
menu selection button settings on the LCD. Press the corresponding menu
selection button to select the desired measurement.
Setup Mode
Use the menu selection but t ons in order to edit desired se t up values as follows :
(4) POWER ON/OFF BUTTON
Press the POWER button for more than 1 second to turn the Meter on.
Auto-Power-Off
This Meter is completely turned off after 30 minutes of no activities. Press the
POWER button to turn the Meter on again. This feature can be disabled (refer
to Section 8.).
(5) BACKLIGHT ON/OFF BUTTON or EXIT BUTTON
Press this button for more than 1 second to turn the backlight on and press this
button again for more than 1 second to turn it off.
Press this button momentarily to always return to the initial display when the
meter is in either SELECT mode or Memory mode. And also press the button
momentarily to exit the Tone Generator mode.
(6) MEMORY BUTTON or TONE BUTTON
Press this button momentarily to activate the memory mode. The display shows
three menu selections : STORE, RECALL and CLEAR .
Press this button for more than 1 second to activate the Tone Generator mode.
(Press the EXIT button to exit the Tone Generator mode.)
(7) TEST BUTTON
Press this but t on momentarily to measure length, distance to an open or a
short, or V.O.P of cable under test.
(1) DISPLAY
Extra-large backlit (ICON type 7 segment) LCD. When the Meter is turned on,
all display segments and symbols appear briefly (during 1.5 seconds) for a
selftest and then the Meter defaults the following initial display.
Initial Display
When shipped out of factory
The Meter defaults V.O.P of 66.0 % and English scale.
When turned on after having been used in the field
The Meter defaults the V.O.P (e.g. 68.0 %) having been used just before it
was turned off.
(2) BNC
A shielded connector for either coaxial cable or A lligator Clip adaptor (a
standard accessory).
Fig. 1
Fig. 2
Button
Function
Press to step
to next digit in
setting value.
Press to
increase
setting value.
Press to
decrease
setting value.
Press to move t o next
Setup.
Press to save all settings
and e xit Set up Mo de
when setting is ended.
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4.1 Principles of operation
The Meter works by measuring the time taken for a signal to travel to the far end of
the cable (or to an intermediate fault) and to return.
The velocity at which the signal is transmit t ed (Velocity of Propagation , that is,
V.O.P) will depend upon the characteristics of the cable to be tested.
The length is computed from the following formula :
travel time X (9.84 X 10
8
) X V.O.P (English measurement)
travel time X (3 X 10
8
) X V.O.P (Metric measurement)
The V.O.P is specified for standard cable types in this manual. However, do not rely
solely on the specified V.O.P because variations of up to 20 % can occur between
batches of cable. There f ore, if accuracy is critical to your situation, y ou must
determine the ac t ual V.O.P of each cable. Verify the length measurement by
measuring a sample cable (longer than 30 ft, or 10 m) of the same cable type you
will be testing.
4.2 How to connect a cable to the Meter
Ensure that no power supply or equipment is connected to the cable to be tested.
Ensure that the far end of the cable to be tested is either open or shorted (not
fitted with a terminator).
Connect the Meter to one end of the cable to be tested.
The cable connection to the Meter is via a BNC connector located at the top of the
Meter. For unterminated cables use the Alligator Clip adaptor as follows.
Coaxial cable : Connec t the red clip to the center wire and the black
clip to the shield.
Shielded cable : Connect the red clip to a wire adjacent to the shield of
the cable and the black clip to the shield.
Unshielded twisted
pair cable : Separate one pair out and connect the two clips to the
two wires of a pair.
Unshielded multi-core
cable : Connect the two clips to any two wires.
4.3 How to set the cable type
The Meter needs to be set for the cable type to be tested before being used to take
measurements.
If the cable type is listed in the library, setting up is simply a matter of selecting the
appropriate cable type from the library.
4.3.1 Selecting a library cable type
The library cable type you will select determines the information about V.O.P and
the abbreviated trade name of the cable to be tested.
1. Turn the Meter on.
2. The Meter will display the previously selected cable se t ting (see Fig. 1 and
Fig. 2) with its V.O.P.
3. P ress the SELECT but t on then the Meter will display both t he LIBRARY
symbol (blinking) and the V.O.P symbol.
4. Press the OK button to set the Meter to the LIBRARY mode. The Meter will
display the information of the LIBRARY No. 1, when the “ ” will be blinking.
4. Meter Operation
Fig. 3
98
“ blinking ”
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5. Scroll through the library using the ,and buttons to find the required
cable type. The types are displayed in the Library Number order. The 39
standard cable types are listed in Section 4.3.2 and Section 4.3.3 will explain
you how to make the library of 20 cus t omer cable types using t he memory
mode.
6. Press the OK button to set the Meter to the required cable type.
The center line segments of 6 digits in the lower display will be blinking until
the TEST button will be depressed.
7. Connect the cable to be tested to BNC connector of the Meter.
8. Press the TEST button to take the required measurements.
The displayed V.O . P will be remained on the LCD even after the TEST
button was depressed in order to inform the user of the V.O.P of the cable
to be tested.
When the Meter will be continuously set to the just same cable type as the
preceding cable type , the Meter will show the preceding display until the
TEST button will be newly depressed.
When t he Meter is turned off it au t oma t ically stores the last setting and will
display this setting when powered up.
Fig. 4
1110
“ blinking ”
4.3.2 Cable library for 39 standard cable types
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4.3.3 Testing cables not included in library
If the cable type to be tested is not in the library, it can s t ill be t ested if t he V.O. P is
known . If the V.O.P is unknown, refer to Sec t ion 4.4.
1. Turn the Meter on.
2. The Meter will display the previously selected cable se t ting [see Initial Display of
Sec t ion 3.(1)] with i t s V .O.P.
3. Press the SELECT button then the Meter will display both the LI B RARY symbol
(blinking) and the V.O. P symbol (see Fig. 3).
4. Press the button then the LIBR A RY symbol will stop blinking and the V.O.P
symbol will be blinking.
5. Press the OK button t o set the Meter to the V.O.P adjusting mode, when the
LIBRARY symbol will disappear, the V.O.P symbol will stop blinking, and the “ ”
segments will start to blink.
The Meter can enter into the Calibrate Cable function to determine the
V.O.P for a known length of cable by pressing any button out of and
buttons when the Meter is in the V.O.P adjusting mode. Then, the will
appear replacing the and “ 30.00 ” will be blinking to alert the user that
a sample cable longer than 30 ft (10 m) is necessary.
Fig. 5
6. Press the OK button again then the default V.O.P value of 66.0 % will start to
blink.
7. Scroll through the V.O.P value between 1.0 % and 99.9 % by using the ,
and buttons to find the required V.O.P value.
8. Press the OK button t o set the Meter to the required V . O . P value.
9. Connect the cable to be tested to BNC connector of the Meter.
10. Press the TEST button to take the required measurements.
For example, the Meter can have the following display .
Fig. 6
Fig. 7
1312
“ blinking ”
“ blinking ”
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4.4 How to determine unknown V.O. P settings
The Calibrate Cable function allows you to determine the V.O.P for a known length
of cable and save i t for additional measurements of unknown lengths of the same
type o f cable. V.O . P settings are stored in nonvolatile memory.
To calibrate a cable manually, per f orm the following steps :
1. Take a sample of the c able at least 30 ft (10 m) in length to obtain the
specified accuracy (longer leng t hs improve accuracy).
2. Measure i t s length by direct measurement .
3. Repeat the step 1 to step 5 of Section 4 . 3.3 then press the button or the
button in order to set the Meter to the Calibrate Cable function, when the
will appear replacing the and “30.00” will be blinking to let you remind that
the length of a sample cable should be at least 30 ft (10 m).
4. Connect the sample cable to the Meter and set t he actual length of the sample
cable using the , and buttons.
NOTE
Lengths measurements are only as accurate as t he V.O. P
setting for the cable to be measured. V.O.P values can vary
substantially between cable manufacturers as well as between
cable lots.
Measure and record the V.O.P of a sample length of cable for
each cable manufacturer, then mark the V.O.P on each cable
drum before installation.
Fig. 8
5. Press the OK button.
6. Press the TEST button to read the V.O.P of the sample cable, when the center
line segment of 6 digits will blink waiting for the next measurement.
For example,
7. Connect the cable to be tested to the Meter.
8. Press the TEST button to take the required measurement.
4.4.1 Expanding cable l ibrary for custom cable types us i ng nonvolatile
memory
The nonvolatile memory of this Meter allows you to store V.O.P values measured in
Section 4.4 to expand the cable library up to 20 custom cable types.
Use the memory mode to store and recall the measured V.O.P values. Press the
MEMORY button momentarily in order to activate the memory mode. The display
shows three menu selections : STORE, RECALL and CLEAR .
For example, if the below display was obtained in Section 4.4,
Fig. 9
Fig. 10
1514
“ blinking ”
“ blinking ”
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STORE : This Meter has 20 internal memory locations from 01 to 20. P ress the
STORE button to store the nex t available memory location when the memory
locations has been partially occupied. Then, the MEM symbol will appear and the
currently available location number will be blinking.
For example, if the location 04 was occupied, the display shows as the Fig. 11.
When all the memory locations are not occupied, the V.O.P segments will display
“ ”.
A particular memory location can be selected using the , and buttons.
Press the OK button to prepare storing the V.O.P value measured in Section 4.4 in
the location 05. Then, the display shows as the Fig. 12.
P ress the STORE button then the Meter will display blinking “ ” while the
measured V.O.P is being stored. The Me t er will display “ ” replacing “ ”
af t er the V . O . P has been stored.
Fig. 11
If you want to cancel storing the V.O.P setting, press the EXIT button to have
the Meter exit memory mode.
RECALL : Select RECALL to review the stored value pressing the RECALL button
after having the Meter enter into the memory mode. The upper display will show the
V.O.P value of the memory location 01 and the 01 (blinking). Select the required
memory location number using the ,and buttons. Press the EXIT button to
exit the memory mode.
For example, if the memory location 05 would be selected, the Meter will display as
follows :
If you want to cancel this RECALL function, press the EXIT button again to exit
the memory mode.
Fig. 12
Fig. 13
16 17
“ blinking ”
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