Underground Cable Tracing Earth Return (Sheath) Fault Locating [...

1

Underground Cable Tracing

&

Earth Return (Sheath) Fault Locating

[ Basic Concept ]

Prepared By:Roger C. ValenciaU.S. & International Technical Service Engineer3M Test & Measurement Systems3M Austin CenterAustin, TX, USA - March 1996

2

INTRODUCINGThe New And Most Advanced Cable & Earth Return (Sheath) Fault Locators

A GLOBAL PRODUCT

FOR

GLOBAL SOLUTIONS

3

Dynatel 2200 Series Cable & Earth Return (Sheath) Fault Locators

TRANSMITTER RECEIVER

Off

On

Dynatel TM 2273 Trace

Output Level

ACCESSORY COMPARTMENT

TM

Dynatel TM 2273

cm

On

Off Hz

Ref

Trace Frequency

Gain Adjust Depth/Current

Fault / Tone

Volume

4

THE RADIO BROADCAST SYSTEM

RADIOTRANSMITTER

RADIO SIGNALRADIO

RECEIVER

??TRANSMITTER??RECEIVER

BY USING A UNI-DIRECTIONAL ANTENNA IN THE RECEIVER, THE DIRECTION AND LOCATION OF THE SIGNAL SOURCE CAN EASILY BE DETERMINED.

THE BASIC CONCEPT OF CABLE TRACING IS THE SAME AS THE ONE USED IN A RADIO BROADCAST SYSTEM.

BOTH SYSTEMS MAKE USE OF THE FOLLOWING:

5

Basic Concept of Cable Tracing

? In cable tracing, the trace conductor is connected to the output of the Transmitter. The CABLE and EARTH (SOIL) must form an electrical circuit where signal current can flow through.

? As the current flows through the cable, its entire length radiates a signal allowing one to trace the cable path using a Receiver.

? Also, as the signal travels further out, its strength gradually deteriorates due to the increasing resistance of the conductors and the capacitances between them.

Ground Rod

Cable Shield

SoilBlack Clip

Far-EndGroundNear-End

GroundRemoved

Red Clip

Current Flow

Current Flow

Strong Signal Decaying Signal

Transmitter

Receiver

6

TERMS COMMONLY USED IN CABLE TRACING

? TRACE CONDUCTOR - any metallic component of a cable which is used to trace the cable path. (Ex: Cable Shield, a conductor of a power cable, or a telephone wire or pair inside a telephone cable, etc.)

? TRACE FREQUENCY - is the selected transmit frequency (Audio or RF) to trace the cable path.

? NEAR-END GROUND - is the grounding point of the trace conductor which is located closer to the Transmitter.

? FAR-END GROUND - is the remote grounding point of the trace conductor which is located further away from the Transmitter.

? TARGET CABLE - the cable being traced.

7

? CONTINUOUSLY GROUNDED CABLE - a cable having its entire outer metallic sheath in direct contact with Earth (Soil). (Ex: A lead cable having no outer insulating jacket).

? CENTER / INNER CONDUCTOR - Any conductor other than, but within, the metallic shield of a cable. (Ex: the center conductor of a coax cable (CATV or a shielded power cable) a wire or a pair of conductors within a shielded telephone cable, etc.).

? EARTH RETURN FAULT - An electrical leakage path between any cable conductor and Earth (Soil).

? SHEATH FAULT - The same as EARTH RETURN FAULT but the current leakage path is between the cable SHIELD andEarth (Soil).

TERMS COMMONLY USED IN CABLE TRACING(con’t ...)

8

CABLE TRACING MODES

? PEAK? NULL?

DIFFERENTIAL? SPECIAL PEAK

9

CABLE TRACING - PEAK MODE

2 1 3

PEAKTRACE

RECEIVER

SOIL

TARGET CABLE

Note:In this mode, a flag appears below the PEAK symbol on top of the LCD display.

Display Indications:?Location #1:??Bargraph - moves to max.

closed position towards center of the display.

??Numeric Indicator -Higher compared to the reading in either location #2 or #3. ??Audio Tone -Stronger compared to that of location #2 or #3.?Location #2:??Bargraph - Opens up or moves

away from center of display.??Numeric Indicator - Lower

compared to that location #1.??Audio Tone - Weaker

compared to that of location #1.?Location #3:??Bargraph - Opens up or moves

away from center of display.??Numeric Indicator - Lower

compared to that of location #1.

??Audio Tone - Weaker compared to that location #1.

10

Cable Tracing - Peak Mode

ONOFF Hz

Trace Frequency Fault/Tone

RefVolume Depth/CurrentGain Adjust

DynatelTM 2273

Cable

Receiver

11

Cable Tracing - Peak Mode

ONOFF Hz



DynatelTM 2273

Cable

Receiver

12

CABLE TRACING - NULL MODE

2 1 3

NULLTRACE

SOIL

TARGET CABLE

RECEIVER

Note:In this mode, a flag appears below the NULL symbol on top of the LCD display.

Display Indications:

Location #1:

? Bargraph - Moves to max. closed position towards center of

display.??Numeric Indicator - Lower

compared to that of location #2 or #3.

? Audio Tone - Weaker compared to that of location #2 or #3.Location #2:

? Bargraph - Opens up away from center of display.

? Numeric Indicator - Higher compared to that of location #1.

? Audio Tone - Stronger than that of location #1.

Loaction #3:

??Bargraph - Opens up away from center of display.

??Numeric Indicator - Higher compared to that of location

#1. ??Audio Tone - Stronger compared to that of location #1.

13

Cable Tracing - Null Mode

ONOFF Hz



DynatelTM 2273

14

Cable Tracing - Null Mode

ONOFF Hz



DynatelTM 2273

15

DIFFERENTIAL MODE(Basic Theory)

Note:In DIFFERENTIAL mode, two sets of

antennas are used, UPPER (Peak & Null coils) and the LOWER (Peak & Null coils).

The “D”istance between the two antenna sets was precisely calculated so that when the RECEIVER is positioned directly over the TARGET CABLE, the UPPER antenna set should receive exactly 50% of whatever signal level the LOWER set is receiving.

In this situation, this signal phase relationship between the two sets of antennas is considered to be at ZERO VALUE.

D

Upper AntennaSet

Lower AntennaSet

TARGET CABLE

SOIL

Null Coil

Peak Coil

16

DIFFERENTIAL MODE(Basic Theory - con’t ...)

??Location #1 - Zero Value Receiver is exactly over target

cable and the UPPER antenna set is receiving exactly 50% of whatever signal level is being received by the LOWER set.

??Location #2 - Positive Value Receiver is moved to the LEFT of the target cable.

??Location #3 - Negative Value Receiver is moved to the RIGHT of the target cable.

3 SIGNAL PHASE VALUES

1 32

TARGET CABLE

SOIL

RECEIVER

POSITIVE

NEGATIVE

ZERO

17

12 3

ZERO-VALUEPOSITIVE

VALUE NEGATIVEVALUE

SOIL

TARGET CABLE

RECEIVER

UPPERANTENNA SET

( Peak & Null Coils)

LOWERANTENNA SET


Location #1: ZERO-VALUE

? Bargraph - moves to a maximum closed position towards the center of the display.

? Numeric indicator -reads higher

compared to location #2 or #3.? Directional Arrows -

both Left & Right arrows appear at the center of the LCDdisplay.

? Audio Tone - solid (not warbling)

DISPLAY INDICATIONS

CABLE TRACING - DIFFERENTIAL MODE (Basic Theory - con’t . . . )

18

Cable Tracing - Differential Mode

ONOFF Hz



DynatelTM 2273

19

12 3

CABLE TRACING - DIFFERENTIAL MODE (Basic Theory - con’t . . . )

ZERO-VALUEPOSITIVE

VALUE NEGATIVEVALUE

SOIL

TARGET CABLE

RECEIVER

UPPERANTENNA SET


LOWERANTENNA SET


Note:When the RECEIVER is moved away from the TARGET CABLE to the LEFT (location #2), the signal phase relationship changes into a POSITIVE VALUE.

Location #2: Positive Value? Bargraph - Opens up and

moves away from the center of the display.

? Numeric Indicator - reads lower compared to location #1.

? Directional Arrow - the RIGHT arrow will appear in the display, meaning the RECEIVERshould be moved to the right.

? Audio Tone - Low, warbling.

DISPLAY INDICATIONS

(con’t...)

20


ONOFF Hz



DynatelTM 2273

21

12 3

CABLE TRACING - DIFFERENTIAL MODE (Basic Theory - con’t...)

ZERO-VALUEPOSITIVE

VALUE NEGATIVEVALUE

SOIL

TARGET CABLE

RECEIVER

UPPERANTENNA SET


LOWERANTENNA SET


Note:When the RECEIVER is moved away from the TARGET CABLE to the right, the signal phase relationship between the two antenna sets changes to a NEGATIVE VALUE. .

Location #3: Negative Value

??Bargraph - Opens up away from the center of the display.

??Numeric Indicator -Lower reading compared to location #1.

??Directional Arrow - The LEFT arrow appears in the display meaning the Receiver should be moved to the left. ??Audio Tone -High, warbling

DISPLAYINDICATIONS

(con’t...)

22


ONOFF Hz



DynatelTM 2273

23

1 2

CABLE TRACING - PEAK MODE(in a congested environment)

BIG PEAK SMALL PEAK

TARGET CABLEOTHER CABLE

SOIL

Note:In this mode, a flag appears below the

PEAK symbol over the LCD display.

DISPLAY INDICATIONS: LOCATION #1:

When the RECEIVER is over the TARGET CABLE

? Bargraph - moves closest towards center of the display.

? Numeric Indicator - Higher compared to location #2.

? Audio Tone - Stronger compared to location #2.LOCATION #2:

When RECEIVER is moved to the right over the OTHER CABLE.

? Bargraph - Opens up and moves away from center of display.

? Numeric Indicator - Lower than that of location #1.

? Audio Tone - Weaker than that of location #1.

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1 2 3

CABLE TRACING - NULL MODE(in a congested environment)

TARGET CABLE

OTHER CABLE

GHOST CABLE

NULLTRACE

CAUTION:

In NULL mode, the concept is that the Receiver will look for a ZERO (NULL) condition or a point where two or more opposing signals

cancel out.

In congested areas, using NULL can lead into what is commonly called a GHOST CABLE situation.

This means that if there are other cables which are close to the TARGET CABLE, the RECEIVER can be fooled by a “NULL” indication which does not really represent the true location of the cable.

This happens when the signal from the TARGET CABLE and the signal from the OTHER CABLE meet insome area between them and cancel out (NULL), see illustration. This can then be interpreted by the Receiver as the location of the cable but actually it is “not”.

Because of this problem, using NULL in congested areas should be avoided.

If one has to use NULL in such environments, it is strongly suggested that cable location must always be verified using PEAK mode.

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1 2 3

CABLE TRACING - NULL MODE(IN A CONGESTED ENVIRONMENT - CON’T...)


GHOST CABLE

NULLTRACE

Note:In this mode, a flag appears below the NULL symbol on top of the LCDdisplay.

DISPLAY INDICATIONS:

Location #1: Receiver is over the TARGET CABLE

? Bargraph - Opens up away from center of display.

? Numeric Indicator - High compared to location #2 &

#3. ? Audio Tone - Strong compared to location #2 & #3.

Location #2: Receiver is moved to the RIGHTtowards the OTHER CABLE andNULLS

? Bargraph - moves closer towards center of display.

? Numeric Indicator - reading goes down and lower than in location #1 & #3.

? Audio Tone - Level goes down significantly compared to location #1 & #3.

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1 2 3

CABLE TRACING - NULL MODE(IN A CONGESTED ENVIRONMENT - CON’T...)


GHOST CABLE

NULLTRACEDISPLAY INDICATIONS

(con’t ...)

Location #3:Receiver is over the

OTHER CABLE

? Bargraph -Opens up away from center of display.

? Numeric Indicator - Higher compared to that of

location #2 but lower than in location #1.

? AudioTone - stronger than that of location #2 but weaker than that of

location #1.

SOIL

27

CABLE TRACING - DIFFERENTIAL MODE(IN A CONGESTED ENVIRONMENT)

0

( + )

( - )

1 2 3

TARGET CABLE OTHER CABLE

GHOST CABLE

CAUTION:

DIFFERENTIAL mode like NULL has the same problem of creating a GHOST CABLE situation when used in congested areas.

If it is to be used in such environ-ments, one has to verify cable location by using PEAK mode, always.

DISPLAY INDICATIONS:

LOCATION #1: Positive Value (Receiver is over the TARGET CABLE)??Bargraph - Opens up and

moves away from center of the display.

??Numeric Indication -Lower compared to location #2 but higher than in location #3.

??Directional Arrow - RIGHTarrow will appear on

display. ??Audio Tone - Low and warbling

SOIL

28

CABLE TRACING - DIFFERENTIAL MODE(IN A CONGESTED ENVIRONMENT - con’t...)

0

( + )

( - )

1 2 3

TARGET CABLE OTHER CABLE

GHOST CABLE

LOCATION #2: - Zero-Value (GHOST CABLE location)??Bargraph - moves towards center of

display to max. closed indication.??Numeric Indicator - Higher

compared to location #1 & #3.??Directional Arrows - Both LEFT &

RIGHT arrows will appear on display.

??AudioTone - Solid (not warbling)

LOCATION #3: - Negative Signal Value (Receiver is over the OTHER CABLE)??Bargraph - Opens up and moves

away from center of the display.??Numeric Indicator - Lower than

that of location #2 & #3.??Directional Arrow - LEFT arrow

appears in display which means the RECEIVER should be moved to the left.??Audio Tone - High and warbling

DISPLAY INDICATIONS(CON’T . . . )

SOIL

29

SPECIAL PEAK MODE(NORMAL VS. SPECIAL)

TARGET CABLE

TARGET CABLE

?Upper & Lower PEAK ? Only Lower PEAKantenna are activated. antenna is activated.

? More accurate (much ? Less accurate (broadsharper response). response).

? Less sensitive - used for ? Very sensitive - usedstandard cable depths for weak signals such

as those from very deep cables.

NORMAL PEAK SPECIAL PEAK

LOWERPEAK COIL

UPPERPEAK COIL

LOWERPEAK COIL

BROAD TRACESHARP TRACE

SOIL

30

IDENTIFYING THE CORRECT CABLEUSING DEPTH AND CURRENT MEASUREMENT MODE

6 in

28 in

1 2

A: DISPLAY IN TRACE MODE

OTHER CABLETARGET CABLE

Note:In A: TRACE mode, both Bargraph and

Numeric indications are based on signal strength.

As shown in the illustration, the OTHER CABLE being closer to the Receiver is registering a higher relative signal strength of 113 with the Bargraph moving more closer to the center of the display.

On the other hand, the TARGET CABLE because it is farther away from the Receiver is only registering a lower relative signal strength of 110 with the Bargraph opening wider and moving away from the center of the display.

In this case, it looks like the OTHER CABLE is the correct cable but actually, it is not.

31

IDENTIFYING THE CORRECT CABLEUSING DEPTH AND CURRENT MEASUREMENT MODE

B: DISPLAY IN DEPTH & CURRENTMEASUREMENT MODE

OTHER CABLETARGET CABLE

A: DISPLAY IN TRACE MODE

Note:In B: DEPTH & CURRENT measurement mode, the

NUMERIC indications are based on the magnitude of the current flowing through the cables.

In position #1, the TARGET CABLE has a relative CURRENT measurement of 94 at the depth of 27 inches. Take note that although the cable is deeper it is giving a much higher current reading than in position #2.

In POSITION #2, the OTHER CABLE has a relative CURRENT measurement of only 46 even though the cable is much less deeper and closer (only 5 in.) to the Receiver.

The indications in the DEPTH & CURRENT measurement mode will therefore positively identify the correct cable.

6 in

28 in

in

1 2

in

32

1. INCHES2. FEET AND INCHES3. CENTIMETERS (cm)

CABLE DEPTH AND CURRENT READOUTS

DEPTH MEASUREMENT OPTIONS

TYPICAL DEPTH & CURRENT READOUTDEPTH = 26 in.CURRENT = 94 (relative)

UNRELIABLE READING

inin

33

TRACING RANGE2200-SERIES CABLE LOCATORS

(Typical Conditions - Direct Connect With Far-End Of Cable Grounded)

FREQUENCIES RANGE

? 577 Hz 577 Hz 49,000 feet (15 Km)

? 8 kHz 8 kHz 19,600 feet (6 Km)

? 33 kHz 33 kHz 9,800 feet (3 Km)

? 200 kHz 133 kHz 4,900 feet (1.5 Km)

US MODEL EXPORT MODEL

34

TIPS IN SELECTING TRACE FREQUENCIES

? Audio frequencies (577Hz or 8kHz) can only be used if the trace circuit resistance is 3000 ohms or less, otherwise use the RF frequencies (33kHz, 133kHz, or 200kHz).

? Higher frequencies are much easier to induced into nearby cables. To minimize induction of unwanted signals to other cables in congested areas, use the lowest possible trace frequency.

? If a CONTINUOUSLY GROUNDED conductor is used for tracing (Ex: uninsulated outer “lead” sheath of a Lead Cable), use DIRECT CONNECT METHOD and the lowest possible trace frequency (577Hz).

35

1. DIRECT CONNECT METHOD2. DYNACOUPLER METHOD3. INDUCTION METHOD

TRANSMITTER HOOKUPS

36

DIRECT CONNECT METHOD( ACCESSORIES USED )

Off

On

Dynatel T M 2273Trace

Output Level

GROUND ROD

DIRECT CONNECT CABLE

2273 CONTROL PANEL

RED CLIP

BLACK CLIP

37

DIRECT CONNECT HOOKUP

1. Place the GROUND ROD into soil and connect the BLACK clip to it.2. Remove the NEAR-END GROUND and connect the RED clip to the cable SHIELD.3. Turn the unit ON in the OHMS function and check for any voltages that may exist on the cable shield. Check the circuit resistance to ground.

?? If circuit resistance is 3000 ohms or less, a solid tone is emitted from the speaker. This means any or all of the trace frequencies can be used. Audio frequencies will have longer range and induced signal to other cables is minimal.If “ALL” is selected, set the transmitter to

“High output..?? If circuit resistance is between 3000 ohms to less than 10,000 ohms, an interrupted tone is emitted from the speaker. Use higher trace

frequencies (8kHz, or 33kHz or 200kHz). The transmitter can be set to “High” output.?? If circuit resistance is more than 3000 ohms but less than 10,000 ohms, an interrupted tone is emitted from the speaker. Use higher trace

frequencies (8kHz, or 33kHz or 200kHz). For stronger signal, set transmitter to “High” output.

CABLE SHIELD

NEAR-END GROUNDREMOVED

FAR-ENDGROUND

RED CLIP

BLACK CLIP

GROUND ROD SOIL

CURRENT FLOW

TRANSMITTERCURRENT FLOW

T1 T2

SOIL

38

DIRECT CONNECT HOOKUP

CABLE SHIELD FAR-ENDGROUND

RED CLIP

BLACK CLIPGROUND

ROD

SOIL

CURRENT FLOW

TRANSMITTER

CURRENT FLOW

SOIL

INNER CONDUCTOR

39

DIRECT CONNECT HOOKUP( DO’S & DON’TS )

1. If far-end of cable is open or not accessible for grounding - use the highest RF trace frequency, only.Note:

This procedure is only applicable if length of cable is long enough (few hundred feet/meters) to permit the highest RF CURRENT to flow through the accumulated distributed capacitance of the cable.

OPEN-END

SOIL

GROUNDROD

BLACK CLIP

RED CLIP

TRANSMITTER

CABLE SHIELD

CURRENT FLOW

DISTRIBUTED CABLE CAPACITANCE

C C C C C C C

40

DIRECT CONNECT HOOKUP( DO’S & DON’TS - CON’T... )

To trace very short lengths of cable, less than 100 feet (30 m):??The far-end of the trace conductor must always be grounded to EARTH SOIL

(illustration A).?? If EARTH/SOIL is not accessible, a WIRE can be used as the current return path, but it must be placed 50 feet (15m) or more away from trace conductor (illustration B).

SHORT CABLE SHORT CABLE

GROUNDROD

BLACK CLIP

RED CLIP

BLACK CLIP

CURRENT FLOW

CURRENT RETURN WIRE

RED CLIP

TRANSMITTERTRANSMITTER

CURRENT FLOW

SOIL

[ A ] [ B ]

FAR-ENDGROUND

FAR-ENDWIRE

CONNECTION

50 FEET (15 m)

41

DYNA-COUPLER METHOD( ACCESSORIES USED )

DYNA-COUPLER

DYNA-COUPLERCABLE

22273 CONTROL PANEL

Off

On

Dynatel T M 2273

Output Level

Trace

42

DYNA-COUPLER HOOKUP

NOTE:??Do not remove NEAR-END and/or FAR-END GROUNDS. Doing so will

break or open the trace circuit and “no” current will flow.??Only the frequencies (8kHz, 33kHz, 133kHz or 200kHz) will work with

the Dyna-Coupler. 577Hz will “not”.

CABLE SHIELD

NEAR-ENDGROUND

FAR-ENDGROUND

SECONDARY CURRENT FLOW

DYNA-COUPLER

SOIL

TRANSMITTER

PRIMARY CURRENT

FLOW


T1 T2

43

DYNA-COUPLER HOOKUP[ DO’S AND DON’TS ]

NOTE:1. If one end of the cable is open or not accessible for grounding to SOIL, it is still possible to trace the cable if it is

long enough (several hundred feet/meters or more) to have the necessary accumulated distributed capacitance which permits the highest trace frequency current to pass through ( ex: 133kHz or 200kHz ).

2. Also, the Dyna-coupler must always be placed close to the grounded end of the cable (illustration “A”).3. Never place the Dyna-coupler at the un-grounded end of the cable (illustration B). It will not work. No secondary

current will flow.

A

B

TRANSMITTER

CABLE SHIELD

TRANSMITTER DYNA-COUPLER

OPEN-END


DISTRIBUTED CABLE CAPACITANCE

SOIL

GROUNDEDEND

CABLE SHIELD

SOIL

OPEN-ENDDYNA-COUPLERGROUNDED

END

C C C C C C

NO SECONDARY CURRENT FLOW

PRIMARYCURRENT FLOW

44

INDUCTION METHOD & HOOKUP

Note:

? To achieve best results, Transmitter must be placed over and as close as possible to the cable and should be in-line with cable path.? NEAR-END and FAR-END of the trace cable/conductor must be GROUNDED to SOIL to maintain continuity of the trace circuit.? Use the high frequencies 133kHz or 200kHz and switch Transmitter to high output.? Induction Method is not recommended in congested areas because the signal can be easily induced to other cables or pipes which is close and in

parallel to the target cable.? Operate the Receiver no less than 50 feet (15 meters) from Transmitter to avoid direct reception of signal.

TRANSMITTER

INTERNAL

TRANSMIT COIL

CABLE SHIELD

NEAR-END

GROUND

FAR-END

GROUND

SOIL


PRIMARY

CURRENT FLOW

45

Ref

Ref

Gain Adjust

Gain Adjust

If signal is too weak.

If signal is too strong.

Reference Gain Level

Reference Gain Level

One Touch Gain AdjustJust press once and you’ve got it...No need for multiple key presses… No Guessing…No Trial & Error...

PEAK PEAK

PEAKPEAK

46

EARTH RETURN (SHEATH) FAULT LOCATE - BASIC THEORY

NOTE:?? In FAULT-LOCATE, the Transmitter forces current to flow through the FAULT/S. It is important that current

flow must be concentrated into the FAULT/S only. To do this, all GROUND or SOIL connections to the trace cable or conductor must be temporarily disconnected.??As the CURRENT enters the SOIL, it creates a VOLTAGE GRADIENT (slope) on the SOIL’s surface (see

illustration on next page).??For best results, the GROUND ROD should be placed into the SOIL, in-line with the cable path.

Off

GROUND ROD

BLACK CLIPRED CLIP

TRANSMITTER

GROUNDINGREMOVED

GROUNDINGREMOVED

VOLTAGEGRADIENT

VOLTAGEGRADIENT

SOIL

CABLE SHIELD

CURRENT FLOW

CURRENT FLOW

47

+9 +8+8 +7 +6 +5 +4 +3+7+6+5+4+3+2 +2

Dynatel T M 2273 Dynatel T M 2273 Dynatel T M 2273

EARTH RETURN (SHEATH) FAULT LOCATE - BASIC THEORY[ CON’T... ]

NOTE:??As the CURRENT enters the SOIL, a VOLTAGE GRADIENT (slope) is created on the soil’s surface.

The A-FRAME is then plugged into the Receiver and it is used to sense voltage potentials along the cable path.The A-FRAME has two probe tips, one is marked RED and the other is GREEN.

??The goal here is to determine when the RED and GREEN tips senses a NULL , a condition where the voltagepotentials at the RED and GREEN tips are the same or zero).

??Once NULL is achieved, the center of the A-FRAME will then represent the location of the FAULT (position #2).

A- FRAME A- FRAME

FAULT

RED

GRN

S O I L R E S I S T A N C E S O I L R E S I S T A N C E

C U R R E N T F L O W C U R R E N T F L O W

1 2 3

Location #1:Red Leg = +3VGreen Leg = +6VBargraph at Green -

Move forward

Location #2:Red Leg = +7VGreen Leg = +7VBargraph floats - NULL

Stop - Fault located

Location #3: Red Leg = +6VGreen Leg = +3VBargraph at Red - Move

back.FROM TRANSMITTER

48

Off

Dynatel T M 2273 Dynatel T M 2273 Dynatel T M 2273

MULTIPLE EARTH RETURN (SHEATH) FAULT LOCATE

NOTE:??A reference must be established by placing the A-FRAME one pace away from the GROUND

ROD (position #1).??Take a reading and press the GAIN/REF ADJUST key to store reference into memory.

Position #1Reading = 124 (Reference)Position #2 Reading = 118 (Major Fault)Position #3 Reading = 90 (Minor Fault)

1 32

VOLTAGEGRADIENT

TRANSMITTER CABLE SHIELD

MAJOR FAULTMINOR FAULT

R

E

D

G

R

N

G

R

N

G

R

N

R

E

D

R

E

D

VOLTAGEGRADIENT

VOLTAGEGRADIENT

CURRENT FLOW

49

2200 SERIES CABLE / EARTH RETURN (SHEATH) FAULT LOCATORS

OPTIONAL

ACCESSORIES

50

ACCESSORIES(CON’T..)

577 Hz33 kHz

Alert

Batt TestOff

Dynatel2205

T MPWR

TOP VIEW

2200

RECEIVER

Dynatel2205

T MPWR 577 Hz

33 kHzAlert

Batt TestOff

2205DEDICATED

EMS MARKER LOCATOR2205

51

Pwr

Wtr

WWtr

TelGas

Batt Test Dynatel2206

T M

CT

577 Hz

33 kHzAlert

Off


TOP VIEW

2200

RECEIVER

2206EMS ALL-MARKER

LOCATOR PwrWtr

WWtrTel

Gas

577 Hz33 kHz

Alert

Batt TestOff

Dynatel2206

T M

CT

TOP VIEW

2206

52

ELECTRONIC MARKER SYSTEM ( E M S )

Basic Theory:

1. Initially , the 2205 / 2206 unit is turned ON in TRANSMIT mode, transmitting a signal to

the MARKER.2. The MARKER in return, absorbs and stores the

received signal energy from the 2205 /2206.3. After the TRANSMIT phase, the 2205 / 2206 unit

switches to RECEIVE mode and then the stored energy in the MARKER starts to discharge.

4. As the signal energy discharges, the MARKER acts as a TRANSMITTER and starts transmitting the signal back to the 2205 / 2206.

5. Once the 2205 / 2206 unit detects the incoming signal from the MARKER, the 2200 RECEIVER emits a continuous audible TONE.The TONE is strongest when the 2205 / 2206 is exactly over the MARKER. Also, theBARGRAPH will move towards the center of the display and indicate its maximum closed position.

6. The cycle is then repeated over and over again until the 2205 / 2206 unit is turned OFF.

CABLE SPLICE CABLE SPLICE

BALLMARKER

BALLMARKER

SOIL SOIL

2200RECEIVER

TONE

2205/2206SIGNAL

MARKERSIGNAL

22052206

22052206

53


ACTIVE DUCT PROBE ( SONDE )

33 kHz RF Signal

SCOTCHMARK ADP

54

ACTIVE DUCT PROBE (SONDE)ACTIVE DUCT PROBE (SONDE)

2200RECEIVER

33 kHz SIGNAL

PLASTIC PIPE

THE APPLICATION:

LOCATING BLOCKAGES OR OBSTRUCTIONS INSIDE PLASTIC DUCTS AND CONDUITS

NOTE:THE ADP SIGNAL MUST BE TRACED IN PEAK

MODE. TO DO THIS, THE 2200 RECEIVER SHOULD BE POSITIONED PERPENDICULAR TO THE ADP.

33 kHz SIGNAL

2200RECEIVER

DENT

PLASTIC PIPE

55

Cable & Pipe Locating TechniquesCable & Pipe Locating Techniques

DynatelDynatel 22002200--Series Cable/Fault LocatorsSeries Cable/Fault Locators

56

Locating NonLocating Non--metallic Pipemetallic Pipe

SignalWire’s distributed

capacitance to earth/soil

Heavy gauge wireFish tape or Snake

Note:

One end of pipe must be accessible. Push a heavy gauge wire, snake or fish tape into the pipe. Because the signal current must pass through the wire’s distributed capacitance toearth/soil, use any of these frequencies (8 kHz, 33 kHz or 200 kHz). Also, set transmitter to ‘HIGH” output, if a stronger signal is required.

Ground Rod

TransmitterSignal Return Path

Earth/Soil

Non-metallic pipe

2250 or 2273

57

Applying Signal To A PipeApplying Signal To A Pipe[Dyna-Coupler Method]

Note:

With the Dyna-Coupler, you can use any of these frequencies (8 kHz, 33kHz or 200kHz)and set the Transmitter to “High” output.

If both far-ends of a pipe section can be or are grounded. The Dyna-Coupler can be placed in any location (1, 2 or 3) along the pipe section.

SignalSignal

Earth Soil

Earth Ground Earth Ground

Dyna-Coupler

1 2 3

Screwdriver Screwdriver

58

Applying Signal To Pipe And Controlling Signal DirectionApplying Signal To Pipe And Controlling Signal Direction[Dyna-Coupler Method]

Screwdriver

Earth Ground

Insulated PipeEarth/Soil

Signal

Note:

With the Dyna-Coupler, you can use any of these frequencies (8 kHz, 33kHz or 200kHz) and set the Transmitter to “HIGH” output.

If the Dyna-Coupler is placed to the right of the Earth Ground, the signal goes to the right.

If the pipe’s far-end to the right is “NOT” grounded, the Dyna-Coupler must be placed as close as possible to the location of the Earth Ground.

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Applying Signal To Pipe And Controlling Signal DirectionApplying Signal To Pipe And Controlling Signal Direction[Dyna-Coupler Method]

Screwdriver

Earth Ground

Signal

Insulated Pipe

Earth/Soil

Note:

With the Dyna-Coupler, you can use any of these frequencies (8 kHz, 33kHz or 200kHz) and set the Transmitter to “HIGH” output.

If the Dyna-Coupler is placed to the left of the Earth Ground, the signal goes to the left.

If the pipe’s far-end to the left is “NOT” grounded, the Dyna-Coupler must be placed as close as possible to the location of the Earth Ground.

Dyna-Coupler

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Applying Signal to PipeApplying Signal to Pipe[Dyna-Coupler Method]

TransmitterSignal CurrentReturn Path

Ground Rod

Metallic Service Line (insulated)

Note:

With the Dyna-Coupler, you can use any of these trace frequencies (8 kHz, 33kHz or 200kHz) and set the Transmitter to “HIGH”output.

In this illustration, the far-end may or may not be grounded. It works either way.

Gas Meter

2250 or 2273

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Applying Signal To Primary Cables[Dyna-Coupler Method]

Dyna-Coupler

Signal

Concentric Neutrals

Earth Ground

Signal Current Return Path

Signal

Signal

Signal

Three-Phase Primary Elbows

Note:

Use Dyna-Coupler to put trace signal to energized primary cables.

Where the Dyna-Coupler is clamped is very important.On three-phase primary cables, the Dyna-Coupler should be clamped on all concentric neutrals and as close as possible to earth ground.With this setup, the signal is coupled onto each cable equally.

Use any one of these trace frequencies (8 kHz 33kHz or 200kHz) and set the Transmitter to “HIGH” output.

Note (con’t):

Do not place the Dyna-Coupler on any individual concentric neutral.

Since the cables are buried in the same trench, the signal goes one way on one cable and comes back the opposite way on the other two. This causes signal cancellation.

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Applying Signal To Primary CablesApplying Signal To Primary Cables[[DynaDyna--Coupler Method]Coupler Method]

Dyna-Coupler

Signal

Concentric Neutrals

Earth Ground

Signal Current Return Path

Single-Phase Primary Elbows

IN

OUT

Signal

Note:

On single-phase primary cables used in a loop configuration, signal cancellation is not a problem.

The signal can be applied with the Dyna-Coupler to the individual concentric neutral of the cable.

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Applying Signal To Tracer WiresApplying Signal To Tracer Wires[Direct[Direct--Connect Method]Connect Method]

Gas Meter

Signal

Signal Current Return PathTransmitter

Service Tracer Wire Main Tracer Wire

Non-metallic Main

Electrical Connection

Twisted

Non-Electrical Connection

Non-metallic pipeSignal

Ground Rod

Far-endEarth Ground

Note:

For best results, ground the far-end and check the circuit resistance to ground using the built-in ohmmeter.

If resistance to ground is 3000 ohms or less, use the lowest trace frequency (577Hz). If it is more than 3000 ohms but less than 10K ohms, you can use 8kHz. If it is 10K ohms or higher, use 33kHz or 200kHz.

Signal

Gas Meter

Non-metallic pipe

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Signal

Signal Current

Return Path

Service Tracer Wire

Non-metallic MainElectrical Connection

Twisted


Signal

Ground Rod

Far-endEarth Ground

Far-end

Earth Ground

Main Tracer

Wire

50%

50%

Transmitter

Note:

If both far-ends of the pipe are grounded, the signal will divide towards each end.

For best results, use 577Hz or 8kHz.

Signal

Non-metallic pipeNon-metallic pipe

Gas Meter

Gas Meter

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Signal Current

Return Path

Service Tracer Wire


Twisted


Signal

Ground Rod

Far-end Ground #1

(removed)Far-end Ground #2

Main Tracer

Wire

Transmitter

Note:

If far-end ground #1 is removed, signal flows towards far-end ground #2.

Measure circuit resistance to ground. If it is 3000 ohms or less, use 577Hz. If it is more than 3000 ohms but less than 10k ohms, use 8kHz. If it higher than 10K ohms, use 33kHz or 200kHz

Signal

Non-metallic pipeNon-metallic pipe

Gas Meter

Gas Meter

2250 / 2273

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Applying Signal To Tracer WiresApplying Signal To Tracer Wires[Direct-Connect Method]

Signal

Signal Current

Return Path

Service Tracer Wire


Twisted


Signal

Ground Rod

Far-end Ground

Main Tracer

Wire

Transmitter

Note:

If the RF frequencies (33kHz or 200kHz) are used in this illustration, all the trace wires will carry the signal through both direct and capacitivecoupling.

Signal

Non-metallic pipe

Non-metallic pipe

Gas Meter

Gas Meter

2250 / 2273

Underground Cable Tracing Earth Return (Sheath) Fault Locating [...

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