U.S. patent application number 17/232246 was filed with the patent office on 2021-07-29 for system and apparatus for detecting faults in an insulation layer of a buried conductor.
The applicant listed for this patent is Radiodetection Limited. Invention is credited to Charles ALEXANDER, Peter MANN, Mark MARSDEN, Jeff THOMPSON.
Application Number | 20210231722 17/232246 |
Document ID | / |
Family ID | 1000005523159 |
Filed Date | 2021-07-29 |
United States Patent
Application |
20210231722 |
Kind Code |
A1 |
MARSDEN; Mark ; et
al. |
July 29, 2021 |
System and Apparatus for Detecting Faults in an Insulation Layer of
a Buried Conductor
Abstract
Methods, systems and locators for detecting faults in an
insulation later of an insulated conductor buried beneath a ground
surface are described. The locator comprises a magnetometer
arranged to detect a magnetic field generated by the alternating
current and to generate a current signal on the basis of the
detected magnetic field, and an Alternating Voltage Gradient
receiver comprising a pair of probes arranged to make electrical
contact with the ground surface, which is arranged to generate a
voltage signal indicative of a voltage between the pair of probes.
A processor is configured to substantially synchronously sample the
current signal and the voltage signal. This enables improved
detection of faults in the insulation layer of the insulated
conductor.
Inventors: |
MARSDEN; Mark; (Bristol,
GB) ; MANN; Peter; (Bristol, GB) ; ALEXANDER;
Charles; (Bristol, GB) ; THOMPSON; Jeff;
(Bristol, GB) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
Radiodetection Limited |
Bristol |
|
GB |
|
|
Family ID: |
1000005523159 |
Appl. No.: |
17/232246 |
Filed: |
April 16, 2021 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
|
16349894 |
May 14, 2019 |
|
|
|
PCT/GB2017/053430 |
Nov 15, 2017 |
|
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17232246 |
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Current U.S.
Class: |
1/1 |
Current CPC
Class: |
G01R 31/083
20130101 |
International
Class: |
G01R 31/08 20060101
G01R031/08 |
Foreign Application Data
Date |
Code |
Application Number |
Nov 15, 2016 |
GB |
1619334.4 |
Claims
1. A locator for detecting faults in an insulation layer of an
insulated conductor buried beneath a ground surface, the insulated
conductor carrying an alternating current, the locator comprising:
a magnetometer arranged to detect a magnetic field generated by the
alternating current and to generate a current signal on the basis
of the detected magnetic field; an Alternating Voltage Gradient
receiver comprising a pair of probes arranged to make electrical
contact with the ground surface, the Alternating Voltage Gradient
receiver being arranged to generate a voltage signal indicative of
a voltage between the pair of probes; a processor configured to
simultaneously sample the current signal and the voltage signal;
and a user interface configured to simultaneously display the
sampled signals.
2. A locator according to claim 1, wherein the processor is
configured to determine a phase difference between the current
signal and voltage signal.
3. A locator according to claim 2, comprising a memory, wherein the
processor is configured to store in the memory current measurements
based on the processed current signal, voltage measurements based
on the processed voltage signal and a phase measurement based on
the determined phase difference between the current signal and
voltage signal.
4. A locator according to claim 3, comprising a position locating
device arranged to determine a position of the locator, wherein the
processor is configured to store, in the memory, position
information relating to the position of the locator when stored
current and voltage measurements were measured.
5. A locator according to claim 4, wherein the processor is
configured to determine a rate of phase difference with respect to
distance determined on the basis of the position information.
6. A locator according to claim 3, comprising a communications
interface for communicating with a portable computing device,
wherein the processor is configured to transmit the current and
voltage measurements to the portable computing device.
7. A locator according to claim 4, wherein the processor is
configured to transmit the current and voltage measurements to the
portable computing device in real time.
8. A locator according to claim 2, wherein the processor is
configured to, in use, obtain survey measurement data, the survey
measurement data comprising, for each of a plurality of different
positions along a survey path traversed by the locator, a current
measurement based on the current signal and a voltage measurement
based on the voltage signal.
9. A locator according to claim 8, wherein the survey measurement
data further comprises, for each of the plurality of different
positions along the survey path traversed by the locator, a phase
difference measurement of the phase difference between the current
signal and the voltage signal.
10. A locator according to claim 9, wherein the processor is
configured to determine, based upon a variation in the phase
difference measurements with distance over a section of the survey
path, information regarding the length of a fault located in an
insulation layer of an insulated conductor buried beneath the
ground surface under the survey path.
11. A locator according to claim 10, wherein the information is an
estimate of the length of the fault.
12. A locator according to claim 9, wherein the locator comprises a
display and the processor is configured to cause a plot of at least
one of: the current measurements; the voltage measurements; and the
phase difference measurements against distance to be displayed on
the display.
13. A locator according to claim 8, comprising a communications
interface for communicating with an external computing device,
wherein the processor is configured to transmit the current and
voltage measurements to the portable computing device.
14. A locator according to claim 12, wherein the external computing
device is a portable computing device.
15. A locator according to claim 10, wherein the alternating
current carried in the insulated conductor has a low frequency
component and a relatively higher frequency component, and wherein
the magnetometer is arranged to detect the magnetic field generated
by the low frequency component.
16. A locator according to claim 15, comprising two magnetic field
sensors each configured to generate a magnetic field signal in
response to a magnetic field generated by the high frequency
component, wherein the processor is configured to determine a depth
of the insulated conductor based on the generated magnetic field
signals.
17. A locator according to claim 1, wherein the simultaneous
sampling causes a survey to be done quicker by being performed in
one pass of the buried conductor.
18. A locator according to claim 1, wherein the current signal is
used to determine a current in the buried conductor.
19. A locator according to claim 10, wherein the locator comprises
a detector for locating the insulated conductor and the
magnetometer is affixed to the detector and the Alternating Voltage
Gradient receiver is mounted in a frame separate to the detector,
wherein, in use: the detector is to be carried in a first hand of
an operator; and the frame is to be held in a second hand of the
operator, different to the first hand.
20. A method for detecting faults in an insulation layer of an
insulated conductor buried beneath a ground surface, the method
comprising: applying an alternating current to the buried
conductor; simultaneously (i) detecting a magnetic field generated
by the alternating current with a magnetometer located above the
ground surface and (ii) measuring a voltage between a pair of
probes in electrical contact with the ground surface; generating
(i) a current signal indicative of a current in the buried
conductor based on the detected magnetic field and (ii) a voltage
signal indicative of the measured voltage; and simultaneously
displaying the current and voltage signals at a user interface.
Description
CROSS REFERENCE TO RELATED APPLICATIONS
[0001] This application claims priority to and is a continuation of
U.S. patent application Ser. No. 16/349,894, filed May 14, 2019,
which is a National Stage of International Patent Application No.
PCT/GB2017/053430, filed on Nov. 15, 2017, and claims priority to
United Kingdom Patent Application No. 1619334.4, filed on Nov. 15,
2016, the contents of which are hereby incorporated by reference in
their entirety.
TECHNICAL FIELD
[0002] The present invention relates to detecting faults in an
insulation layer of an insulated conductor buried beneath a ground
surface.
BACKGROUND
[0003] Buried metal pipelines are typically coated with a layer of
insulating material to act as a barrier to current flow between the
pipe and ground, in order to minimise the possibility of
electrolytic corrosion. To add further protection, the conventional
use of cathodic protection systems applies a standing DC voltage of
negative potential to the pipe, in order to ensure that any
electrolytic corrosion that does occur in the event of coating
defects or damage is confined to so-called ground beds which act as
sacrificial anodes, and the positive terminals for the voltage.
Such ground beds typically cover an area of tens of square metres
near the cathodic protection application point.
[0004] Over extended periods of time, faults in the insulating
material can result in degradation of the pipeline, and so the
condition of pipelines is typically surveyed regularly. Such
surveys involve comparative measurement of resistance to ground of
pipeline sections; by storing the information gained from
successive surveys, any change in the condition of the pipeline can
be detected, and corrective action taken.
[0005] Various methods of surveying are known. In one such survey,
an alternating current is injected into the pipe, and a hand-held
receiver is used firstly to locate the position of the pipe and
then, by measuring depth and signal strength, to determine the
amplitude of the injected signal current at each position. From
these measurements at known distances along the pipe, the rate of
loss of signal voltage and current can be plotted to identify
faults in the insulating material.
SUMMARY
[0006] According to a first aspect of the present invention, there
is provided locator for detecting faults in an insulation layer of
an insulated conductor buried beneath a ground surface, the
insulated conductor carrying an alternating current, the locator
comprising:
[0007] a magnetometer arranged to detect a magnetic field generated
by the alternating current and to generate a current signal on the
basis of the detected magnetic field;
[0008] an Alternating Voltage Gradient receiver comprising a pair
of probes arranged to make electrical contact with the ground
surface, the Alternating Voltage Gradient receiver being arranged
to generate a voltage signal indicative of a voltage between the
pair of probes; and
[0009] a processor configured to substantially synchronously sample
the current signal and the voltage signal.
[0010] According to a second aspect of the present invention, there
is provided a system for detecting faults in an insulation layer of
an insulated conductor buried beneath a ground surface, the system
comprising:
[0011] a locator comprising:
[0012] a magnetometer arranged to detect a magnetic field generated
by the alternating magnetic current and to generate a current
signal in response to detecting the magnetic field;
[0013] an Alternating Voltage Gradient receiver comprising a pair
of probes arranged to make electrical contact with the ground
surface, the Alternating Voltage Gradient receiver being arranged
to generate a voltage signal indicative of a voltage between the
pair of probes; and
[0014] a processor configured to process the current signal and the
voltage signal substantially simultaneously; and
[0015] a signal generator arranged to apply an alternating current
to the buried conductor.
[0016] According to a third aspect of the present invention, there
is provided a method of detecting faults in an insulation layer of
an insulated conductor buried beneath a ground surface, the method
comprising:
[0017] applying an alternating current to the buried conductor;
[0018] simultaneously detecting a magnetic field generated by the
alternating current with a magnetometer located above the ground
surface and measuring a voltage between a pair of probes in
electrical contact with the ground surface;
[0019] generating a current signal on the basis of the detected
magnetic field and generating a voltage signal indicative of the
measured voltage; and
[0020] processing the current signal and the voltage signal
substantially simultaneously.
[0021] According to a fourth aspect of the present invention, there
is provided a non-transitory machine-readable storage medium
storing instructions that, when executed by a processor in a
portable computing device, cause the processor to:
[0022] simultaneously receive current and voltage measurements, the
current measurement being based on a current signal generated on
the basis of a magnetic field detected with a magnetometer located
above the ground surface and the voltage measurement being based on
a voltage signal measured between a pair of probes in electrical
contact with the ground surface;
[0023] determining a phase difference between the current signal
and voltage signal; and
[0024] display the current and voltage measurements and the
determined phase difference at the portable computing device.
[0025] According to a fifth aspect of the present invention, there
is provided a non-transitory machine-readable storage medium
storing instructions that, when executed by a processor in a
locator for detecting faults in an insulation layer of an insulated
conductor buried beneath a ground surface, cause the processor
to:
[0026] receive a current signal generated by a magnetometer in
response to the magnetometer detecting a magnetic field;
[0027] receive a voltage signal generated by an Alternating Voltage
Gradient receiver, the voltage signal being indicative of a voltage
between a pair of probes of the Alternating Voltage Gradient
receiver; and
[0028] process the current and voltage signals simultaneously.
[0029] Further features and advantages of the invention will become
apparent from the following description of preferred embodiments of
the invention, given by way of example only, which is made with
reference to the accompanying drawings.
BRIEF DESCRIPTION OF THE DRAWINGS
[0030] FIG. 1 is a schematic diagram showing a system for detecting
faults in an insulation layer of an insulated conductor buried
beneath a ground surface, according to an example;
[0031] FIG. 2 is a schematic diagram showing a fault detector for
detecting faults in an insulation layer of an insulated conductor
buried beneath a ground surface, according to an example;
[0032] FIG. 3 is a block diagram showing electronic components of a
fault detector for detecting faults in an insulation layer of an
insulated conductor buried beneath a ground surface, according to
an example;
[0033] FIG. 4 is a schematic diagram showing a system for detecting
faults in an insulation layer of an insulated conductor buried
beneath a ground surface, according to an example;
[0034] FIG. 5 is a display screen provided by an application
according to an example;
[0035] FIGS. 6a and 6b illustrate plots of various measurements as
a function of distance in respect of a survey over a point fault
and a longer fault respectively;
[0036] FIG. 7 is a display screen provided by an application
according to an example;
[0037] FIG. 8 is a flow diagram showing a method of detecting
faults in an insulation layer of an insulated conductor buried
beneath a ground surface, according to an example; and
[0038] FIG. 9 a schematic diagram showing a processing device
according to an example.
DETAILED DESCRIPTION
[0039] Standard industry practice is to perform multiple surveys on
any given pipeline to confirm the presence of faults in the
insulating material. Typically, after a first survey is performed,
the operator or a suitably trained surveyor, reviews the measured
data to identify potential faults in the insulating material. A
second survey, using a different measurement technique, is then
performed around locations where potential faults in the insulating
material have been identified. For example, a first survey may be
performed using the method described above. The first survey may
identify possible locations of faults in the insulating material.
Then a second survey may be performed using a different or more
accurate fault detection technique. However, surveying a pipeline
in this way relies on the first survey identifying all potential
faults in the insulating material; otherwise the second survey will
not be carried out in locations where a potential fault in the
insulating material is missed and the fault will not be
identified.
[0040] FIG. 1 shows an example system TOO for detecting faults 102
in an insulation layer 104 of an insulated conductor 106 buried
beneath a ground surface 108. The system TOO includes a fault
detector 110 and a signal generator, referred to herein as a
transmitter 112.
[0041] The transmitter 112 is arranged to apply an alternating
current to the buried conductor 106. The signal generated by the
transmitter 112 comprises one or more frequency components. In
certain examples, the transmitter 112 generates one or more
frequency components in a low frequency range for finding faults in
the insulating layer 104, and one or more frequency components in a
relatively higher frequency range (referred to hereinafter as the
high frequency range) for locating the buried conductor 106 and/or
determining the depth of the buried conductor 106 beneath the
ground surface 108.
[0042] In some examples, in the low frequency range, the
transmitter 112 may generate one or more signals having a frequency
less than 10 Hz for finding faults in the insulating layer 104. For
example, the transmitter 112 may generate a 4 Hz signal. In another
example, the transmitter 112 may generate a 4 Hz signal and an 8 Hz
signal.
[0043] In some examples, in the high frequency range, the
transmitter 112 may generate one or more signals having a frequency
higher than 10 Hz for locating the buried conductor 106 and/or
determining the depth of the buried conductor 106 beneath the
ground surface 108. For example, the transmitter 112 may generate a
128 Hz signal. In another example, the transmitter 112 may generate
a 98 Hz signal. In some examples, the transmitter 112 may generate
two or more signals in the high frequency range to enable the
locator 110 to determine the depth at more than one frequency.
[0044] In some examples, the transmitter 112 may be conductively
coupled to an exposed portion of the buried conductor. In this
case, one terminal of the transmitter 112 is connected directly, by
an operator, to the pipe or cable at an access point such as a
valve, meter or end of the conductor and the circuit is completed
by a connection of another terminal of the transmitter 112 to a
ground stake or other ground connection point.
[0045] FIG. 2 shows an example of a fault detector 200. The fault
detector 200 includes a locator 202. The locator 202 comprises a
housing 204 which contains components for detecting a buried
conductor as described below with reference to FIG. 3. The housing
204 comprises a handle 206 which is held in one hand of a user
during use of the fault detector 200. Adjacent to the handle 206 is
a display 207 for displaying information to the user is while
holding the locator 202. The housing 204 has a section which
extends from the handle 206 towards the ground surface 108 during
use, which may contain antennas for detecting high frequency
magnetic fields, such as a 128 Hz magnetic field, generated by
current flowing in a buried conductor, such as the current applied
by the transmitter 112.
[0046] A foot unit 208 is connected to the locator 202. The foot
unit 208 houses a magnetometer 210 which is arranged to detect low
frequency magnetic fields, such as a 4 Hz magnetic field, generated
by current flowing in a buried conductor, such as the current
applied by the transmitter 112. The foot unit 208 contains a
ball-and-socket joint 212 and the magnetometer 210 is electrically
connected to components within the housing 204 via an electrical
connection 214. The ball-and-socket joint 212 allows the foot unit
208 to remain in the same orientation with respect to the ground
surface 108 if the locator 202 is moved relative to the plane of
the ground surface.
[0047] The fault detector 200 also comprises an Alternating Voltage
Gradient receiver, referred to herein as a voltage A-frame 216. The
voltage A-frame 216 comprises a pair of probes 218. The probes 218
are arranged to make electrical contact with the ground surface
108, and to generate a voltage signal indicative of a potential
difference between the probes 218. The voltage A-frame 216 also
comprises a handle 220 by which the voltage A-frame 216 is held in
a second hand of the user during use of the fault detector 200. The
voltage A-frame is electrically connected to components within the
housing 204 by a cable 222.
[0048] In some examples, the foot unit 208 and/or the voltage
A-frame 216 are disconnectable from the locator 202. In other
examples, the foot unit 208 and/or the voltage A-frame 216 are
integral with the locator 202.
[0049] FIG. 3 shows the electronic components of the fault detector
200. The locator 202 comprises a pair of vertically spaced antennas
comprising a top antenna 300 and a bottom antenna 302 that are
arranged to detect high frequency magnetic fields generated by
current applied by the transmitter 112. The antennas 300, 302 are
arranged with their axes parallel and spaced apart so that in use
the bottom antenna 302 will be directly below the top antenna 300,
their axes being horizontal. Each antenna 300, 302 produces an
electrical signal which is received by a respective
analogue-to-digital converter (ADC). A first ADC 304 converts
electrical signals from the top antenna 300 into a first digital
signal and a second ADC 306 converts electrical signals from the
bottom antenna 302 into a second digital signal. The processor 308
is configured to receive the first and second digital signals and
to calculate an estimate of the depth of the buried conductor based
on the relative magnitudes of the magnetic fields represented by
the first and second digital signals (i.e. detected by the top and
bottom antennas 300, 302).
[0050] The processor 308 is configured to receive input data from
an input module 310. For example, the input module 310 may be a key
pad, or a touch-screen input device via which the user can input
commands. The processor 308 is connected to the display 207 and may
cause the display 207 to display information to the user. In some
examples, the display 207 and the input module 310 may be a single
touch-screen display.
[0051] The locator 202 comprises a magnetometer interface 312 for
receiving a current signal from the foot unit 208 and an ACVG
interface 314 for receiving a voltage signal from the voltage
A-frame 216. The foot unit 208 comprises an ADC 316 for digitising
the current signal for sending to the processor 308 via the
magnetometer interface 312. Similarly, the voltage A-frame 216
comprises an ADC 318 for digitising the voltage signal for sending
to the processor 308 via the ACVG interface 314.
[0052] The processor 308 executes instructions stored in a memory
320 contained within the locator 202. In order to operate the fault
detector 200 to detect faults such as the fault 102 in the
insulation layer 104 of the insulated conductor 106, the user may
select a fault detection mode of the locator 202 by inputting an
appropriate input to the input module 310. To use the fault
detector 200 in the fault detection mode, the user carries the
locator 202 to which the foot unit 208 is connected in one hand and
carries the voltage A-frame 216 in another hand. Having located the
buried conductor 106, the user carries the locator 202 and the
voltage A-frame 216 along the path of buried conductor 106. In some
examples, in the fault detection mode, the user may be required to
stop at regular distance intervals to take current and voltage
measurements. In other examples, the fault detector 200 may sample
current and voltage measurements at regular time intervals.
[0053] In the fault detection mode, the processor 308 is arranged
to process the current signal received from the foot unit 208 and
the voltage signal received from the voltage A-frame
simultaneously. Current and voltage measurements that are
simultaneously processed by the processor 308 are stored in the
memory 320 by the processor 308. In some examples, the processor
may be configured to simultaneously display the current and voltage
amplitude and phase measurements to the user in real time (i.e. as
the user is operating the fault detector 200).
[0054] As explained above, prior art methods of surveying buried
conductors for faults in their insulation typically require two or
more surveys to be conducted at different times and/or by different
operators. One reason for this is that prior art apparatus for
conducting different types of survey only allow for one type of
measurement to be performed and processed at a time.
[0055] Measuring current and voltage signals simultaneously enables
a phase difference between the current and voltage at a given
location to be determined. For example, the phase difference
between current and voltage signals at 4 Hz may be determined. Such
phase information is not available where current and voltage
signals are measured separately, at different times.
[0056] In some examples, the phase difference may be used to
evaluate the length of a fault 102 in the insulation layer 104. The
voltage phase undergoes a polarity transition before and after the
fault 102. A small fault may result in a distinct phase change
and/or a rapid rate of phase change around the fault 102, whereas a
larger fault (extending along a greater length of the conductor
106) may result in a phase change that is highly disturbed and/or
extends over a greater distance.
[0057] In some examples, the processor 308 is configured to, in
use, obtain survey measurement data, the survey measurement data
comprising, for each of a plurality of different positions along a
survey path traversed by the fault detector 200 during a survey, a
current measurement based on the current signal and a voltage
measurement based on the voltage signal.
[0058] The survey measurement data obtainable by the processor 308
may further comprise for each of the plurality of different
positions along the survey path a phase difference measurement of
the phase difference between the current signal and the voltage
signal.
[0059] The processor 308 may be configured to determine, based upon
how the phase difference measurements vary with distance over a
section of the survey path, information regarding the length of a
fault (for example, an estimate of the length of the fault) located
in an insulation layer of an insulated conductor buried beneath the
ground surface under that section of the survey path.
[0060] In some examples, the locator 202 may comprise a location
determining unit, such as a global positioning unit (GPS) 322. In
such examples, the processor 308 may be arranged to store position
information corresponding to a position where current and voltage
measurements were simultaneously measured in the memory 320.
[0061] In certain examples, the locator 202 may comprise one (as
shown) or more communications interfaces 324. The one or more
communications interfaces 324 may be arranged to transmit and/or
receive data to and/or from other computing devices. For example,
the one or more communications interfaces 324 may enable
communications via Bluetooth, WiFi, WiMAX, and/or any other kind of
proprietary communications and signalling technologies. The one or
more communications interfaces 324 may include a transceiver. The
transceiver may provide radio and signal processing as needed to
transmit and/or receive data to and/or from other computing devices
or to access a network.
[0062] FIG. 4 shows another example of a system 400 for detecting
faults in an insulation layer of an insulated buried conductor.
Similar to the system described above with reference to FIG. 1, the
system comprises a fault detector, such as the fault detector 200
described above with reference to FIG. 2, and a transmitter
112.
[0063] In some examples, the fault detector 200, with the locator
202 set in fault detection mode, may send a command to the
transmitter 112 to cause the transmitter 112 to generate the low
frequency component. In some examples, the command may be sent via
the one or more communications interfaces 324.
[0064] In some examples, the fault detector 200 (e.g. the locator
202) may be connected to one or more computing devices 402 via the
one or more communications interfaces 324. For example, the locator
202 may be paired with a portable computing device, such as a
tablet or smartphone, via a Bluetooth connection and/or any other
kind of proprietary communications and signalling technologies. In
another example, the locator 202 may be networked with a portable
computing device, such as a laptop personal computer, via a WiFi
connection and/or any other kind of proprietary communications and
signalling technologies.
[0065] The computing device 402 may execute an application for
receiving data from the fault detector 200. In some examples, the
application may process and/or analyse data received from the fault
detector 200, as described below with reference to FIG. 8. This may
provide a larger, or higher quality, display on which to display
information relating to detected faults to the user.
[0066] In some examples, the computing device may be arranged to
connect to a communications network. The communications network may
include one or more of a cellular network, a wireless local area
network, a wired local area network, a wide area network, a wired
telecommunications network, and the internet 404. For example, the
communications network may include one or more of Global System for
Mobile Communications (GSM), Universal Mobile Telecommunications
System (UMTS), Long Term Evolution (LTE), 5G (5th generation mobile
networks or 5th generation wireless systems), fixed wireless access
(such as IEEE 802.16 WiMax), wireless networking (such as IEEE
802.11 WiFi and IEEE 802.15 ZigBee) and/or any other kind of
proprietary communications and signalling technologies. Data
relating to data received from the fault detector 200 may be
transmitted via the communications network and stored remotely for
off-site review and/or analysis.
[0067] In some examples, the computing device 402 may comprise a
position determining unit, such as a GPS unit instead of or in
addition to the GPS unit 322 described above in relation to FIG. 3.
In some examples, the computing device 402 may store position
information corresponding to a position where current and voltage
measurements were simultaneously measured in a memory of the
computing device 402. Such position information may be used to
confirm or augment the accuracy of previously stored position
information, or provide position information where that information
has not been recorded by the locator 202; for example, where the
locator transmits current and voltage measurements to the computing
device 402 in real time without position information.
[0068] In some examples, the computing device may be additionally
or alternatively paired with a dedicated GPS device 406, and the
computing device 402 may store position data based on position
information provided by the GPS device 406. This may, for example,
provide more accurate information regarding the position where
current and voltage measurements were simultaneously measured.
[0069] In some examples, the transmitter 112 may be provided with a
position determining unit, such as a GPS unit. In such examples,
since the position of the transmitter 112 is generally fixed during
a fault detection survey, the position of the transmitter 112 may
be determined with a high degree of accuracy and a differential
position measurement (such as a differential GPS measurement) may
be made by comparing position information determined by the GPS
unit of the locator 202, or the computing device 402, or the GPS
device 406, with the position of the transmitter 112.
[0070] FIG. 5 shows a first example of a display screen 500 that
may be provided by an application running for processing the
current and voltage measurements.
[0071] In FIG. 5, current measurements 502, based on magnetic field
measurements made using the magnetometer 210, and voltage
measurements 504 made using the voltage A-frame 216, are plotted as
a function of distance and simultaneously displayed to the user.
This data may be retrieved from the memory 320 of the locator 202
after a survey has been completed, or may be displayed in real time
(i.e. during a survey) to the user of the fault detector 200,
either on the display 207 of the locator 202 or on a display of a
computing device 402 such as a tablet or smartphone.
[0072] In some examples, the current and voltage amplitude and
phase measurements are displayed in units of degrees, dBmA and dBmV
to compensate for higher current flowing in the buried conductor
106 at locations closer to the transmitter 112 and conversely lower
current flowing in the buried conductor 106 at locations further
from the transmitter 112. Consequently, using the unit of current
measurement, equal sized faults yield substantially equal changes
in the current and voltage measurements.
[0073] As shown in FIG. 5, faults 102 in the insulation layer 104
appear in the current measurements 502 as changes in gradient 506
of the graph of current as a function of distance. Faults 102 in
the insulation 104 appear in the voltage measurements as distinct
minima 508 in the graph of voltage as a function of distance.
[0074] Plotting both current, voltage and phase simultaneously
provides the user with more data with which to diagnose faults 102.
In contrast with prior methods of surveying a buried conductor,
since the current and voltage measurements are taken
simultaneously, only one pass of the buried conductor is required.
Furthermore, taking both current and voltage measurements
simultaneously reduces the likelihood of a fault being missed in a
first survey and therefore not being investigated further by a
second survey.
[0075] Referring now to FIGS. 6a and 6b, there are illustrated
plots of (1) current measurements 900, based on magnetic field
measurements made using the magnetometer 210; (2) voltage
measurements 902 made using the voltage A-frame 216, and (3) phase
difference measurements 904 between the current measurements and
the voltage measurements, all three as a function of distance over
a section of a survey path traversed by the fault detector 200
during a survey. Each individual measurement is represented as a
dot in the plots. The fault detector 200 may comprise any suitable
distance measurer, for example, an accelerometer, for measuring
distances between measurement points. This distance measuring
function may, for example, be performed by the processor 308 and/or
any required additional hardware and may be in addition to or
instead of any of the GPS functionality described above. In these
examples, the distance between measurement points is in the range 5
cm to 50 cm, for example, and is preferably in the range of 10 cm
to 30 cm, and is preferably around 20 cm.
[0076] As shown in FIG. 6a, a point or relatively short fault in
the insulation layer of a buried conductor under the survey path
shows in the plot of current measurements 900 as a change in
gradient over a short section, in the plot of voltage measurements
902 as a trough, and most noticeably, in the plot of phase
difference measurements 904, as a relatively large peak.
[0077] As shown in FIG. 6b, a non-point like fault or a longer
fault in the insulation layer of a buried conductor under the
survey path shows in the plot of current measurements 900 as a
change in gradient over a relatively long section, in the plot of
voltage measurements 902 as a sequence of three troughs, and most
noticeably, in the plot of phase difference measurements 904, as a
sequence of three relatively large peaks.
[0078] In general, the change or variation in the phase difference
measurements taken along the region of a point like or short fault
in an insulation will be sharp and well defined whereas the change
or variation in the phase difference measurements taken along the
region of a longer fault in an insulation will be more random or
chaotic but repeatable.
[0079] Accordingly, in some examples, the processor 308 is
configured to analyse the variation in the phase difference
measurements with distance and generate information regarding the
length of a detected fault. For example, the processor 308 may
generate an estimate of the length of the fault or categorise the
fault as being a point fault or a longer fault. This information
may be presented to an operator on a display screen of the locator
202.
[0080] In other examples, a plot of at least the phase difference
measurements as a function of distance may be presented to a user
on a display of the fault detector 200 and the user may estimate
the length of a fault his or herself based on the plot.
[0081] As already discussed above, in some examples, the data
obtained by the fault detector 200 may be transmitted to a portable
computing device and this device may process/analyse the data and
present to a user on a display a plot of at least the phase
difference measurements as a function of distance from which a user
can estimate the length. Additionally, or alternatively, the
portable computing device may generate the information regarding
the length of a detected fault, for example, an estimate of the
length of the fault or categorise the fault as being a point fault
or a longer fault.
[0082] It should be appreciated that repeat surveys taken at
different times will enable a user to monitor the state of a fault
over time and identify whether a fault is stable or changing. For
example, a comparison of the plots of the phase difference
measurements as a function of distance in the region of a fault
taken at different times may indicate that a fault is stable (i.e.
the plots are relatively similar), a point fault is corroding into
a longer fault (i.e. an earlier plot looks like FIG. 6a but a later
plot like FIG. 6b for example) or that a long fault is increasing
in length over time (i.e. the chaotic region in an earlier plot
extends over a smaller distance than it does in the later
plot).
[0083] FIG. 7 shows a second example of a display screen 600 that
may be provided by an application running for processing the
current and voltage measurements. In FIG. 7, positions 602 at which
current and voltage measurements were simultaneously made are
displayed on a map of the surveyed area. This enables the user to
easily and accurately indicate the points on the buried conductor
where faults are suspected for future maintenance or repair.
[0084] FIG. 8 shows a method 700 of detecting faults in an
insulation layer of an insulated conductor buried beneath a ground
surface, according to an example.
[0085] At block 702, an alternating current is applied to the
buried conductor. The alternating current may comprise one or more
frequency components in a low frequency range for finding faults in
the insulating layer 104, and one or more frequency components in a
high frequency range for locating the buried conductor 106 and/or
determining the depth of the buried conductor 106 beneath the
ground surface 108.
[0086] In some examples, in the low frequency range, one or more
signals having a frequency less than 10 Hz may be generated for
finding faults in the insulating layer 104. For example, a 4 Hz
signal may be generated. In another example, a 4 Hz signal and an 8
Hz signal may be generated by the transmitter.
[0087] In some examples, in the high frequency range, one or more
signals having a frequency higher than 10 Hz may be generated for
locating the buried conductor 106 and/or determining the depth of
the buried conductor 106 beneath the ground surface 108. For
example, a 128 Hz signal may be generated. In some examples, two or
more signals in the high frequency range may be generated to enable
the depth to be determined at more than one frequency.
[0088] At block 704, a magnetic field generated by the alternating
current is detected with a magnetometer located above the ground
surface and simultaneously, a voltage between a pair of probes in
electrical contact with the ground surface is measured.
[0089] At block 706, a current signal is generated on the basis of
the detected magnetic field and a voltage signal indicative of the
measured voltage is generated.
[0090] At block 708, the current signal and the voltage signal are
processed simultaneously. For example, the current signal and the
voltage signal may be stored as current and voltage measurements
corresponding to a single location in a memory. In another example,
the current signal and the voltage signal may be transmitted as
current and voltage measurements corresponding to a single location
to a computing device for analysis.
[0091] As described above, certain methods and systems as described
herein may be implemented by a processor that processes computer
program code that is retrieved from a non-transitory storage
medium. For example, the method 700 may be implemented by computer
program code that is implemented by a computing device 402.
[0092] In this context, FIG. 9 shows an example of a processing
device 800 comprising a machine-readable storage medium 802 coupled
to a processor 804. In certain cases the processing device 800 may
comprise a stand-alone computing device, such as a desktop computer
or server communicatively coupled to fault detector; in other cases
the processing device 800 may comprise part of a fault detector.
The machine-readable medium 802 can be any medium that can contain,
store, or maintain programs and data for use by or in connection
with an instruction execution system. Machine-readable media can
comprise any one of many physical media such as, for example,
electronic, magnetic, optical, electromagnetic, or semiconductor
media. More specific examples of suitable machine-readable media
include, but are not limited to, a hard drive, a random access
memory (RAM), a read-only memory (ROM), an erasable programmable
read-only memory, or a portable disc. In FIG. 8, the
machine-readable storage medium comprises program code to implement
the methods described above.
[0093] At block 806, the processor 800 simultaneously receives
current and voltage measurements. The current measurement is based
on a current signal generated on the basis of a magnetic field
detected with a magnetometer located above the ground surface. The
voltage measurement is based on a voltage signal measured between a
pair of probes in electrical contact with the ground surface.
[0094] At block 808, the processor 800 displays the current and
voltage measurements at the portable computing device.
[0095] Additionally, the various aspects of the disclosure may be
implemented in a non-generic computer implementation. In one
aspect, the various processors may be implemented as fault
detection processors, surveying processors, location detection
processors, and the like. Moreover, the various aspects of the
disclosure set forth herein improve the functioning of the system
as is apparent from the disclosure hereof. Furthermore, the various
aspects of the disclosure involve computer hardware that is
specifically programmed to solve the complex problem addressed by
the disclosure. Accordingly, the various aspects of the disclosure
improve the functioning of the system overall in its specific
implementation to perform the process set forth by the disclosure
and as defined by the claims. Additionally, the disclosure provides
meaningful limitations placed upon the application of the claimed
operations to show that the claims are not directed to performing
mathematical operations on a computer alone. Rather, the
combination of elements impose meaningful limits in that the
mathematical operations are applied to improve an existing
technology by improving fault detection to extend the usefulness of
the technology.
[0096] Aspects of the disclosure directed to proprietary
communications and signalling technologies may include
communication channels that may be any type of wired or wireless
electronic communications network, such as, e.g., a wired/wireless
local area network (LAN), a wired/wireless personal area network
(PAN), a wired/wireless home area network (HAN), a wired/wireless
wide area network (WAN), a campus network, a metropolitan network,
an enterprise private network, a virtual private network (VPN), an
internetwork, a backbone network (BBN), a global area network
(GAN), the Internet, an intranet, an extranet, an overlay network,
Near field communication (NFC), a cellular telephone network, a
Personal Communications Service (PCS), using known protocols such
as the Global System for Mobile Communications (GSM), CDMA
(Code-Division Multiple Access), GSM/EDGE and UMTS/HSPA network
technologies, Long Term Evolution (LTE), 5G (5th generation mobile
networks or 5th generation wireless systems), WiMAX, HSPA+, W-CDMA
(Wideband Code-Division Multiple Access), CDMA2000 (also known as
C2K or IMT Multi-Carrier (IMT-MC)), Wireless Fidelity (Wi-Fi),
Bluetooth, and/or the like, and/or a combination of two or more
thereof. The NFC standards cover communications protocols and data
exchange formats, and are based on existing radio-frequency
identification (RFID) standards including ISO/IEC 14443 and FeliCa.
The standards include ISO/IEC 18092[3] and those defined by the NFC
Forum.
[0097] Aspects of the disclosure may be implemented in any type of
computing devices, such as, e.g., a desktop computer, personal
computer, a laptop/mobile computer, a personal data assistant
(PDA), a mobile phone, a tablet computer, cloud computing device,
and the like, with wired/wireless communications capabilities via
the communication channels.
[0098] Aspects of the disclosure may be implemented in any type of
mobile smartphones that are operated by any type of advanced mobile
data processing and communication operating system, such as, e.g.,
an Apple.TM. iOS.TM. operating system, a Google.TM. Android.TM.
operating system, a RIM.TM. Blackberry.TM. operating system, a
Nokia.TM. Symbian.TM. operating system, a Microsoft.TM. Windows
Mobile.TM. operating system, a Microsoft.TM. Windows Phone.TM.
operating system, a Linux.TM. operating system or the like.
[0099] Further in accordance with various aspects of the
disclosure, the methods described herein are intended for operation
with dedicated hardware implementations including, but not limited
to, PCs, PDAs, semiconductors, application specific integrated
circuits (ASIC), microprocessors, programmable logic arrays, cloud
computing devices, and other hardware devices constructed to
implement the methods described herein.
[0100] According to an example, the global positioning unit or
global positioning device may be any type of global navigation
satellite system (GNSS) and may include a device and/or system that
may estimate its location based, at least in part, on signals
received from space vehicles (SVs). In particular, such a device
and/or system may obtain "pseudorange" measurements including
approximations of distances between associated SVs and a navigation
satellite receiver. In a particular example, such a pseudorange may
be determined at a receiver that is capable of processing signals
from one or more SVs as part of a Satellite Positioning System
(SPS). Such an SPS may comprise, for example, a Global Positioning
System (GPS), Galileo, Glonass, to name a few, or any SPS developed
in the future. To determine its location, a satellite navigation
receiver may obtain pseudorange measurements to three or more
satellites as well as their positions at time of transmitting.
Knowing the SV orbital parameters, these positions can be
calculated for any point in time. A pseudorange measurement may
then be determined based, at least in part, on the time a signal
travels from an SV to the receiver, multiplied by the speed of
light. While techniques described herein may be provided as
implementations of location determination in GPS and/or Galileo
types of SPS as specific illustrations according to particular
examples, it should be understood that these techniques may also
apply to other types of SPS, and that claimed subject matter is not
limited in this respect.
[0101] The application described in the disclosure may be
implemented to execute on an Apple.TM. iOS.TM. operating system, a
Google.TM. Android.TM. operating system, a RIM.TM. Blackberry.TM.
operating system, a Nokia.TM. Symbian.TM. operating system, a
Microsoft.TM. Windows Mobile.TM. operating system, a Microsoft.TM.
Windows Phone.TM. operating system, a Linux.TM. operating system or
the like. The application may be written in conjunction with the
software developers kit (SDK) associated with an Apple.TM. iOS.TM.
operating system, a Google.TM. Android.TM. operating system, a
RIM.TM. Blackberry.TM. operating system, a Nokia.TM. Symbian.TM.
operating system, a Microsoft.TM. Windows Mobile.TM. operating
system, a Microsoft.TM. Windows Phone.TM. operating system, a
Linux.TM. operating system or the like.
[0102] Aspects of the disclosure may include a server executing an
instance of an application or software configured to accept
requests from a client and giving responses accordingly. The server
may run on any computer including dedicated computers. The computer
may include at least one processing element, typically a central
processing unit (CPU), and some form of memory. The processing
element may carry out arithmetic and logic operations, and a
sequencing and control unit may change the order of operations in
response to stored information. The server may include peripheral
devices that may allow information to be retrieved from an external
source, and the result of operations saved and retrieved. The
server may operate within a client-server architecture. The server
may perform some tasks on behalf of clients. The clients may
connect to the server through the network on a communication
channel as defined herein. The server may use memory with error
detection and correction, redundant disks, redundant power supplies
and so on.
[0103] The above embodiments are to be understood as illustrative
examples of the invention. Further embodiments of the invention are
envisaged. It is to be understood that any feature described in
relation to any one embodiment may be used alone, or in combination
with other features described, and may also be used in combination
with one or more features of any other of the embodiments, or any
combination of any other of the embodiments. Furthermore,
equivalents and modifications not described above may also be
employed without departing from the scope of the invention, which
is defined in the accompanying claims.
* * * * *