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Radiodetection 3300 Скачать руководство пользователя страница 26

When testing a section of cable where different types of

cable are spliced together, use the independent cursors and

the correct VOP for each section of cable to yield the most

accurate readings.

3.4 Cable Impedance

Any time two metallic conductors are placed close together,

they form a transmission line which has a characteristic

impedance. A TDR tests for a change in impedance which

can be caused by cable damage, water ingress, change in

cable type, improper installation, taps and “tees”, and even

manufacturing flaws.

The insulating material that keeps the conductors separated

is called the cable dielectric. The impedance of the cable

is determined by the conductor diameter, the spacing of

the conductors from one another, and the type of dielectric

or insulation used.

The Model 3300 uses an output pulse balance circuit that

cancels the output pulse out of the waveform display and

matches the instrument to the cable under test. Model 3300

still displays fault reflections which occur in this region.

3.5 Velocity of Propagation (VOP)

Determining the VOP

Knowing the correct velocity of propagation is one of the

most important factors in successfully finding the distance

to a fault. A quick reference VOP card is included with

each instrument.

The VOP of a cable not listed on the VOP card can be

obtained from the manufacturers’ catalog specifications or

by contacting the manufacturer. If you cannot obtain the

VOP of a particular type of cable, the VOP can be deter-

mined by the following method:

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Содержание 3300

Страница 1: ...Model 3300 Twisted Pair Metallic Time Domain Reflectometer Operation Manual 250 0023 03 ...

Страница 2: ...commitment to quality and excellence and will do our best to continue to provide you with test equipment to meet your needs Please read the operator s manual thoroughly to ensure the best results from your TDR As always Radiodetection welcomes your comments and suggestions Radiodetection 28 Tower Road Raymond ME 04071 USA Tel 1 207 655 8525 Toll Free 1 877 247 3797 Fax 1 207 655 8535 Email rd sale...

Страница 3: ...irst time Start Up 25 3 2 Cable Connection 25 3 3 Cable Check 25 3 4 Cable Impedance 26 3 5 VOP 26 3 6 PulseWidths 28 3 7 Noise Filter Powered Cable 29 SECTION 4 APPLICATION NOTES 30 4 1 Locating Splits and Resplits 30 4 2 Locating BridgedTaps 31 4 3 Moisture in Twisted Pair 40 4 4 Locating Intermittent Faults 42 SECTION 5 WAVEFORM EXAMPLES 44 SECTION 6 MAINTENANCE 53 SECTION 7 SPECIFICATIONS 55 A...

Страница 4: ...ore using review all safety precautions Note and ob serve all warning and caution statements on the equipment and in the documentation Do not operate this instrument near flammable gases or fumes Do not modify any part or accessory of this instrument If the unit is damaged do not use Make sure the product is secured from use by others To avoid electric shock do not remove covers or any parts of th...

Страница 5: ... fault locator Model 3300 is designed to quickly and easily locate cable faults in metallic cables primarily on non loaded twisted pair cable in the telecom munications industry Using time domain reflectometry or cable radar the Model 3300 transmits a signal down the cable Impedance dis continuities along the length of the cable reflect some or all of the signal energy back to the instrument These...

Страница 6: ...S 2 1 Theory of Operation A Time Domain Reflectometer TDR works on the same basic principle as radar Pulses of energy are transmitted down the cable under test If the cable has a constant im pedance and is properly terminated all of the energy will be absorbed If the pulse reaches an impedance discontinuity part or all of the pulse energy is reflected back to the instrument If the cable is an open...

Страница 7: ... are out of phase or downward Inductive faults cause the TDR to display an impedance higher than the characteristic impedance of the cable be ing tested Capacitive faults cause the TDR to display an impedance lower than the characteristic impedance of the cable The Model 3300 displays the cable under test as a digi tized waveform and a numeric distance readout on the Liq uid Crystal Display The di...

Страница 8: ...i n e 1 P u l s e 1 0 0 n s e c V O P V G a i n 4 x V O P 6 5 L 1 1 5 d B R L t t a B e c n a l a B P r e s s f o r m e n u 1 3 1 f t 200 1 0 2 BACK LIGHT CONTRAST CONTRAST ZOOM OUT ZOOM IN V GAIN V GAIN RANGE RANGE CURSOR CURSOR WAVEFORM POSITION ...

Страница 9: ...in Range Use the two range keys to increase and decrease the cable distance displayed on screen Pulse width and vertical gain are automatically adjusted for each range Cursor Use the two arrow keys to move the cursor left and right A menu will pop up when the asterisk key is pressed The unlabeled icon keys control a selection cursor for choosing the desired instrument control Once the control is s...

Страница 10: ...Back panel description RS 232 CHARGER LINE 1 LINE 2 12V ...

Страница 11: ...ck is charged by plugging the external battery charger into the charging socket and AC power The Model 3300 may be operated while the batter ies are charging as long as the charge level is above the minimum level Twisted pair cables are connected to the Model 3300 by way of the telco test leads Test leads connect to the Line 1 and Line 2 banana jack connectors ...

Страница 12: ...he Liquid Crystal Display LCD are A MESSAGE CENTER The message center displays various information about the status of the instrument and waveform display modes Additional messages are dis played when utilizing the standard and optional waveform storage functions B PULSE WIDTH Model 3300 has selectable pulse widths for testing various lengths of cable L i n e 1 P u l s e 1 0 0 n s e c VO P V G a i...

Страница 13: ...TWEEN CURSORS Model 3300 au tomatically calculates and displays the distance between the 1st and 2nd cursors or between a cursor and the zero distance reference depending on the setup configuration See Setup Options Menu in Section 2 3 Each time the cursor placement is changed or the VOP is adjusted the DISTANCE BETWEEN CURSORS reading will auto matically update I BATTERY LEVEL INDICATOR A horizon...

Страница 14: ...se the key to store a waveform to an available storage location Recall Use the key to recall a stored waveform from memory and display the list of the stored waveforms Overlay Use the two icon keys to adjust the trace separa tion in dual waveform display modes This control is only available when two waveforms are displayed Mode Use the two icon keys to cycle through the available display modes for...

Страница 15: ...rough a menu of cable types in order to obtain the correct VOP of the cable being tested P r e s s t o s e l e c t P u l s e O v e r l a y V O P M o d e B a l a n c e P r i n t F i l t e r S e a r c h S e t u p C a b l e S t o r e R e c a l l ...

Страница 16: ...ce of cable The transmitted pulse is on the left side of the screen and the cable span is shown to the right The exact length of cable on the screen for each range will be relative to the VOP being used When using Range you still have complete manual control and can change the pulse width zoom level and other key func tions as needed With the distance format set in feet mode and a 65 VOP the range...

Страница 17: ...transmitted pulse to the cursor Accuracy of the distance reading is dependent on the placement of the cursor and an accurate VOP Dual Cursor Operation When a test is initiated the independent cursors are used to measure the distance to a fault or to the end of the cable The cursors are interchangeable but to reduce confusion use the 1st cursor to mark the point you are measuring from and the 2nd c...

Страница 18: ... reading always zoom in on the reflected pulse and adjust cursor placement manually The distance between the cursors is displayed on the LCD Remember that the distance measurement is not from the transmitted pulse but from the first cursor to the second cursor Accuracy of the distance reading is dependent on the placement of the cursors and an accurate VOP 2 3 3 Display Modes There are a number of...

Страница 19: ...djusted repositioned zoomed in and out and the cursors moved without affecting the IFD function The Model 3300 will monitor the cable waiting for an intermittent fault to occur Upon entering the intermittent fault mode The LCD s waveform area displays and saves the maximum and minimum reflections of the wave form trace The auto off 10 minute timer is disabled so the instrument does not turn off in...

Страница 20: ...a minimum safe level the instrument will turn itself off to prevent possible battery damage 3 Waveforms can be stored and taken back to the office for downloading to a serial printer for archiving Storing an IFD Waveform To store an IFD waveform select Store from the pop up menu while in the IFD mode The instrument will save the intermittent waveforms in a dedicated IFD memory loca tion If a wavef...

Страница 21: ... the waveform display Increasing the ver tical gain of the waveform display allows the user to see smaller reflections or minor faults on the cable signature 2 3 8 Setup Options Menu Before using the Model 3300 there are several setup op tions you can choose from The options chosen will re main selected even when the instrument is turned off Options available Distance format FEET or METERS Distanc...

Страница 22: ...e test leads Note Always use the test leads provided Using test leads of a different length will result in erroneous distance measurements The serial printer option is used to select the type of serial printer for RS 232 printing The options available are Seiko DPU 411 thermal printer and the Citizen PN60 plain pa per printer 2 3 9 Waveform Storage and Recall Model 3300 s SUPER STORE waveform stor...

Страница 23: ...RECALL is highlighted A memory selection list will appear allowing the user to select the desired memory location If any waveforms are currently stored in memory the op erator may choose the stored waveform by scrolling to the desired number When the desired location number is high lighted press to select the stored waveform to be dis played with the live waveform All instrument functions will ope...

Страница 24: ... limits battery charge current As the batteries ap proach maximum charge the charging rate is decreased Do not leave the batteries charging for long periods of time their useful life will be shortened The Model 3300 can be charged with either an AC or DC power source with cor rect voltage and current specifications The Model 3300 will operate while charging as long as the battery level indicator i...

Страница 25: ...nana jack connector provides the ver satility to test in and adapt to various kinds of environ ments and industries 3 3 Cable Check Do a quick check of the cable Get as close to the sus pected fault as possible Use common sense when exam ining the area near the suspected fault For example if there is a new fence or sign post that is probably where the prob lem is located One method for verifying t...

Страница 26: ...d by the conductor diameter the spacing of the conductors from one another and the type of dielectric or insulation used The Model 3300 uses an output pulse balance circuit that cancels the output pulse out of the waveform display and matches the instrument to the cable under test Model 3300 still displays fault reflections which occur in this region 3 5 Velocity of Propagation VOP Determining the...

Страница 27: ...CEDURE 1 Procedure 1 assumes only one fault per cable length If there are extreme changes in the VOP set ting multiple faults may be present or the cable route may be incorrect Testing a cable from both ends is the most common and most accurate method of eliminating VOP error Using a cable locator and measuring wheel deter mine the length and path of the cable being tested Test the cable from both...

Страница 28: ...ted and therefore the further the signal will travel down the cable NOTE Always start the fault finding procedure in the shortest pulse width available the fault may be only a short distance away Use the zoom and gain controls If the fault is not located switch to the next larger pulse width and retest Keep switch ing to larger pulse widths until the fault is located Cable Loss Cable has loss A si...

Страница 29: ...t The POWERED CABLE WARNING will appear in the message center If you must test a powered cable the Model 3300 features NOISE FILTERS which allow the testing of cables with some signal or power present If the Model 3300 is con nected to a cable with power present the microprocessor automatically filters the power signal and displays only the normal waveform of the cable under test When the NOISE FI...

Страница 30: ...ent types of signals that can be present on the cable They range from 50 60 Hz power to audio frequency to data in the 1 to 100 MHz range to RF No single filter will eliminate all of these signals Riser Bond Instruments waveform TDRs have multiple types and lev els of filters which eliminate almost any type of problem In a filtering application it is necessary for the operator to step through vari...

Страница 31: ... split pair to Line 1 and the other pair to Line 2 Set the Model 3300 to display Line 1 and adjust the 1st cursor to the 0 distance marker Cycle the Model 3300 display mode to the Crosstalk mode The Crosstalk mode transmits the TDR pulse on Line 1 and receives on Line 2 If any energy is coupled from pair 1 to pair 2 split or resplit it will return to the instrument and be displayed on the waveform...

Страница 32: ...ridged tap to the subscriber will be referred to as the lateral Figure 1 is a common waveform which results from testing a section of cable containing a bridged tap from which a lateral extends to the subscriber Referring to Figure 1 you might assume the following Point A the TDR s point of connection to the cable Point B downward reflection the point of a bridged tap on the main cable Point C the...

Страница 33: ... 1b show two different cable plant layouts However the resulting waveforms are identical Figure 1a Figure 1b In Figure 1a the length of the lateral is shorter than the end of the main cable circuit In Figure 1b the length of the lateral is longer than the main cable circuit LESSON Do not assume the first upward reflection after a bridged tap is always the end ...

Страница 34: ...ged taps and their corresponding laterals A great deal of information is displayed in the waveform Therefore a thorough study of the waveform and cor rect cursor placement becomes very important In the following examples we will use the cable layout as shown in Figure 1a where the first downward reflec tion is the bridged tap the next upward reflection is the end of the lateral and the last upward...

Страница 35: ...istance from the TDR to the end of the lateral The distance between the two cursors is the distance from the TDR to the end of the main cable There is no need to subtract the length of the lateral This is an advantage of a TDR over an open locator ...

Страница 36: ...The distance between the two cursors is the length of the lateral The distance between the two cursors is the distance from the bridged tap to the end of the main cable ...

Страница 37: ...igure 2 The fault could be in either the lateral or the main cable Figure 2 Figure 3 is a waveform from the cable plant layout in Figure 1a The reflection caused by a fault is obviously located in the main cable beyond the point of the bridged tap and not the lateral It is always a good idea to go to the bridged tap point and test both the lateral and the main cable beyond the point of bridged tap...

Страница 38: ...m function to show only a specific section of cable in Figure 4 The amount of cable shown on the display is not enough to see the end of the lateral or the end of the cable Figure 4 Figure 5 Remember when testing with a TDR always start the test in the shortest pulse width or range possible Con tinue to increase the pulse width or range until the entire waveform has been viewed This procedure will...

Страница 39: ...lly ends at Point D Referring to the cable plant layout in Figure 6b the ghost is caused when the signal returning from Point D passes Point B The signal splits some energy returning straight to the TDR Point D and some energy traveling down the lateral reflecting from the end and returning to the TDR Point E after the reflection of the end of the cable Figure 6a A B C D Figure 6b ...

Страница 40: ...ad ability is reduced from that point outward If you can normally test 6 000 feet in a particular pulse width or range you may only be able to see 3 000 feet beyond due to the bridged tap 4 3 Moisture in twisted pair A subscriber complained about a noisy telephone line The noise was traced to the drop The subscriber had a 2 800 foot two pair drop to the home along a country road ditch through the ...

Страница 41: ...in the cable or splice case In air core or pulp cable moisture can migrate along the cable By testing the cable from both ends and recording the distance to fault in all pairs it is possible to determine approximately how much cable is affected When testing through water measurements up to the water are very accurate After the water distance read ings may be erroneous due to a VOP change caused by...

Страница 42: ...ittent faults The first indication of an intermittent fault is when a telephone customer com plains of noisy static or no dial tone The problem is usually a high resistance series fault or intermittent connectors Many times the customer calls with a noisy telephone line However by the time the trouble crew is deployed there is no trouble found When there is no loop current the fault heals itself A...

Страница 43: ...nue to keep the butt set con nected to the pair with the silent termination 5 Switch on the TDR by touching the I O key 6 Initiate the IFD mode by cycling through the various display modes 7 Wait for the fault to occur The Model 3300 will dis play a live waveform while monitoring the line for any intermittent waveforms If an intermittent fault occurs the trace of the fault area will be superimpose...

Страница 44: ...ent will look different on a short length of cable than it will on a long length of cable Various industries cable types and components produce many different waveforms The TDR s pulse width hori zontal zoom and vertical gain settings all affect how a waveform will appear Practice testing various known cable segments with and without components Become familiar with how each seg ments looks prior t...

Страница 45: ...dicates a fault with SHORT low impedance tendencies The reflection shown at the second cursor is a DEAD SHORT L i n e 1 P u l s e 1 0 0 n s e c V O P V G a i n 4 x V O P 6 5 L 1 1 0 d B R L B a l a n c e B a t t P r e s s f o r m e n u 5 0 6 f t 2 1 L i n e 1 P u l s e 1 0 0 n s e c V O P V G a i n 4 x V O P 6 5 L 1 1 0 d B R L B a l a n c e B a t t P r e s s f o r m e n u 5 0 6 f t 2 1 ...

Страница 46: ...hm series resistance fault at the 2nd cursor 1000 feet followed by a complete open at 2000 feet L i n e 1 P u l s e 1 0 0 n s e c V O P V G a i n 2 4 x V O P 6 5 L 1 3 2 d B R L B a l a n c e B a t t P r e s s f o r m e n u 5 0 7 f t 2 1 L i n e 1 P u l s e 1 0 0 n s e c V O P V G a i n 4 8 x V O P 6 5 L 1 1 5 d B R L B a l a n c e B a t t P r e s s f o r m e n u 1 0 0 3 f t 2 1 ...

Страница 47: ...cursor is trapped by the Intermittent Fault Detection IFD Mode L i n e 1 P u l s e 2 5 n s e c V O P V G a i n 2 x V O P 6 5 L 1 0 9 d B R L B a l a n c e B a t t P r e s s f o r m e n u 2 6 f t 2 1 L i n e 1 P u l s e 2 5 n s e c V O P A m p 4 x V O P 5 4 B a l a n c e B a t t P r e s s f o r m e n u 1 3 1 f t 2 1 ...

Страница 48: ...NWARD reflection similar to a SHORT followed by a smaller positive reflection L i n e 1 P u l s e 1 u s e c V O P V G a i n 8 x V O P 6 5 L 1 1 0 d B R L B a l a n c e B a t t P r e s s f o r m e n u 1 5 0 1 f t 2 1 L i n e 1 P u l s e 1 0 0 n s e c V O P V G a i n 1 0 x V O P 6 5 L 1 2 8 d B R L B a l a n c e B a t t P r e s s f o r m e n u 4 9 7 f t 2 1 ...

Страница 49: ...sted pair cable Increasing the pulse width and vertical gain is necessary to see a distant fault L i n e 1 P u l s e 5 n s e c VO P V G a i n 4 x V O P 6 5 L 1 1 4 d B R L B a l a n c e B a t t P r e s s f o r m e n u 4 9 f t 2 1 L i n e 1 P u l s e 1 u s e c VO P A m p 5 2 x V O P 5 4 L 1 3 5 d B R L B a l a n c e B a t t P r e s s f o r m e n u 6 0 3 0 f t 2 1 ...

Страница 50: ... both ends to eliminate this problem Description of test setup measuring from the near end L i n e 1 P u l s e 1 0 0 n s e c V O P V G a i n 3 2 x V O P 6 5 L 1 2 6 d B R L B a l a n c e B a t t P r e s s f o r m e n u 5 0 5 f t 2 1 Test First series Second series End of point resistance series cable Point A at 500 ft resistance at 2000 ft 5 Ohm at 1500 ft Point B 30 Ohm ...

Страница 51: ...L i n e 1 P u l s e 1 0 0 n s e c V O P V G a i n 3 2 x V O P 6 5 L 1 10 d B R L B a l a n c e B a t t P r e s s f o r m e n u 5 0 5 f t 2 1 Test First series Second series End of point resistance series cable Point A at 500 ft resistance at 2000 ft 30 Ohm at 1500 ft Point B 5 Ohm ...

Страница 52: ...Only the pulse width setting of the instrument has been changed L i n e 1 P u l s e 5 n s e c V O P V G a i n 4 x V O P 6 5 L 1 1 5 d B R L B a l a n c e B a t t P r e s s f o r m e n u 5 0 f t 2 1 L i n e 1 P u l s e 1 0 0 n s e c V O P V G a i n 4 x V O P 6 5 L 1 0 d B R L B a l a n c e B a t t P r e s s f o r m e n u 5 0 f t 2 1 ...

Страница 53: ... Periodic Inspection To maintain the TDR in peak operating condition periodi cally inspect the instrument and accessories to make sure there is no damage worn or missing parts or deformations in the enclosure If the unit is regularly operated in harsh dusty or wet envi ronments inspect after every use The instrument should be inspected and cleaned periodi cally Inspect the front panel connectors f...

Страница 54: ...uments or another authorized repair facility Warning To avoid risk of electric shock do not perform service of any type to the instrument or any accessory Instrument Disposal This instrument is equipped with non user serviceable Nickle Metal Hydride batteries Should this instrument need to be disposed of please consult your local regula tions as to the standard disposal procedures ...

Страница 55: ...to 500 C 320 F to 1220 F Storage Temperature 200 C to 600 C 40 F to 1400 F Humidity 95 maximum relative non condensing DistanceAccuracy 0 5 ft 0 15 m plus 0 01 of reading Safety EN61010 1 Display 320 x 240 dot matrix liquid crystal display with electroluminescent backlighting Power Battery Internal rechargeable 7 2V Nickel Metal Hydride Charging Source External 12 VAC transformer 1 3 A Operating T...

Страница 56: ...6x 32x 64x 128x Averaging Input Protection 400 V AC DC from DC to 400 Hz decreasing to 10 V at 1 MHz Velocity of Propagation Two user selectable display formats VOP with 2 digit precision ranging from 30 to 99 V 2 with 3 digit precision feet or meters per microsecond ranging from 45 to 148 in meters mode or from 148 to 487 in feet mode Standard Accessories Operator s manual 12 VAC charger padded c...

Страница 57: ...N60 Pocket Printer Riser Bond Instruments Model 3300 will print to the Citizen PN60 Pocket Printer through the Epson LQ 860 command set The printer setup parameters are as follows Language English Font Roman Font Lock Off Line Spacing 6 LPI Character Set Italics Code Page USA Space Skip Enable Stylewriter Auto Protocol DTR Emulation Epson Pitch 10 CPI Compress Off Form Length 11 letters Slash Zero...

Страница 58: ... to trans mit The serial printer cable connections are as follows 9 Pin 26 Pin 3300 Printer 2 15 Rx 4 18 DTR 5 1 2 GND 7 20 RTS RS 232 pin connections for the Serial I O printer port APPENDIX B VOP Table Twisted Pair CABLE AWG MM VOP PIC 19 912 72 22 643 67 24 511 66 26 404 64 JELLY 19 912 68 FILLED 22 643 62 24 511 60 26 404 58 PULP 22 643 67 24 511 68 26 404 66 ...

Страница 59: ... of merchantability or fitness for a particular purpose This warranty does not cover a Periodic maintenance and repair or parts replacement due to wear and tear b Consumables components that are expected to require periodic replacement during the lifetime of a product such as non rechargeable batteries bulbs etc c Damage or defects caused by use operation or treatment of the product inconsistent w...

Страница 60: ...1 800 665 7953 rd sales ca spx com www radiodetection com Radiodetection Ltd UK Western Drive Bristol BS14 0AF UK Tel 44 0 117 976 7776 rd sales uk spx com www radiodetection com Radiodetection France 13 Grande Rue 76220 Neuf Marché France Tel 33 0 2 32 89 93 60 rd sales fr spx com http fr radiodetection com Radiodetection Benelux Industriestraat 11 7041 GD s Heerenberg Netherlands Tel 31 0 314 66...

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