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WO1991000525A1 - Systeme de detection de champ electrique - Google Patents

Systeme de detection de champ electrique Download PDF

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Publication number
WO1991000525A1
WO1991000525A1 PCT/US1990/003374 US9003374W WO9100525A1 WO 1991000525 A1 WO1991000525 A1 WO 1991000525A1 US 9003374 W US9003374 W US 9003374W WO 9100525 A1 WO9100525 A1 WO 9100525A1
Authority
WO
WIPO (PCT)
Prior art keywords
electric field
signal
field signal
aircraft
antenna
Prior art date
Application number
PCT/US1990/003374
Other languages
English (en)
Inventor
William E. Merritt
Joel Johnson
Original Assignee
Merritt William E
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Merritt William E filed Critical Merritt William E
Publication of WO1991000525A1 publication Critical patent/WO1991000525A1/fr

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Classifications

    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01R—MEASURING ELECTRIC VARIABLES; MEASURING MAGNETIC VARIABLES
    • G01R29/00—Arrangements for measuring or indicating electric quantities not covered by groups G01R19/00 - G01R27/00
    • G01R29/08—Measuring electromagnetic field characteristics
    • G01R29/0807—Measuring electromagnetic field characteristics characterised by the application
    • G01R29/0814—Field measurements related to measuring influence on or from apparatus, components or humans, e.g. in ESD, EMI, EMC, EMP testing, measuring radiation leakage; detecting presence of micro- or radiowave emitters; dosimetry; testing shielding; measurements related to lightning
    • G01R29/085—Field measurements related to measuring influence on or from apparatus, components or humans, e.g. in ESD, EMI, EMC, EMP testing, measuring radiation leakage; detecting presence of micro- or radiowave emitters; dosimetry; testing shielding; measurements related to lightning for detecting presence or location of electric lines or cables

Definitions

  • the present invention relates generally to a system for detecting an electrical power line, and more specifically to an improved detector and
  • the magnetic field is detected by two vertical loop antennas, with each antenna defining a planar area and receiving a horizontal component of the magnetic field.
  • the antennas are preferably positioned perpendicular to one another.
  • a signal processor is provided to receive and interpret the magnetic field which is sensed by the vertical pair of antennas, and determines therefrom the direction of the power line emitting the magnetic field relative to the helicopter.
  • the Young et al power line detector compensates for the extraneous magnetic fields from sources other than the power line. For example, the effects of any static magnetic fields surrounding the antennas are cancelled by using three pairs of Helmholtz coils.
  • a flux valve is used to cancel the earth's magnetic field, and a latitude selector or attitude data unit compensates for the latitude or attitude of the helicopter. Compensation for local variations in the earth's magnetic field is provided by a unit
  • the Young et al detection system merely indicates the relative direction of a power line from a helicopter, and provides an early warning of the presence of power lines. It does not provide or even suggest such useful outputs as the distance or range of the helicopter from the power line, or the time remaining until the helicopter would impact the power line.
  • Another magnetometer device for use on board an aircraft to detect the position of a magnetic source, such as a submarine, relative to the aircraft is disclosed in United States Patent No. 4,309,659 to Yoshii. As shown, four magnetometer units A, B, C and D are positioned at the aircraft nose, tail and wing tips, respectively. The magnetometer units measure components of the magnetic field in two and in three mutually perpendicular directions. These components, along with a gyroscope signal, are inputs provided to a signal processor.
  • Magnetometer systems such as that of Yoshii, typically detect variations in the earth's magnetic field caused by the presence of large magnetic
  • the position of the magnetic body is computed relative to the position of the magnetometer system.
  • the signal processor computes the distance, direction, attitude and magnetic moment to locate the magnetic source being sought.
  • aircraft equipped with magnetometers for determining the location of a magnetic source are flown with wings level, even while making turns, otherwise pitch and roll compensation must be included in the magnetometer system.
  • proximity alarms for warning a heavy equipment operator, such as a crane operator, that the boom of the crane is approaching an energized power line.
  • a heavy equipment operator such as a crane operator
  • One such device is disclosed in United States Patent No. 3,745,549 to Jepperson et al, which detects the proximity of the power line by detecting the electrostatic field associated therewith
  • An antenna is mounted to the heavy equipment extre mity, such as the boom of a crane, the forks of a forklift truck, or the ladder portion of a ladder truck.
  • a switching and control circuit includes antenna sensitivity controls, test circuitry and alarm circuitry.
  • the alarm may be either a light or an audible signal which merely warns the operator when the equipment extremity enters the electrostatic field associated with an energized power line.
  • Jepperson et al device Further useful information is not provided by the Jepperson et al device, such as the direction of the power line relative to the equipment
  • Jepperson et al device also requires calibration. If the
  • a proximity detector for warning the operator of a backhoe that the backhoe bucket is approaching an underground conduit is disclosed in United
  • United States Patent No. 3,889,179 to Cutler discloses a portable buried pipe locator. External excitation of the pipe by an external power supply is required to provide an emission source to generate an electric field which is detected by the locator.
  • Such a locator first requires that an external location of the pipe be known and the connection be made.
  • the depth of the buried pipe is computed by a triangulation method using multiple readings in the devices of both Slough et al and Cutler.
  • FIG. 1 is an unsealed perspective view of an aircraft and illustrates an electric field detector embodying the present invention
  • FIG. 1B illustrates on an enlarged scale
  • FIGS. 2, 3 and 4 are diagrams and graphs illustrating the theory of operation of the present invention including in FIG. 4 a plot of experimental test data,
  • FIG. 5 is a circuit diagram of one form of a signal conditioning means that forms part of the
  • FIG. 6 is a block diagram of one form of a
  • FIGS. 7A and 7B illustrate apparatus used to detect the electric field in the vicinity of an
  • FIG. 8 shows a detail of FIG. 1A in order to illustrate how the direction of a power line can be determine
  • FIG. 9 illustrates how apparatus similar to that shown in FIG. 7B might be used on an aircraft to determine the direction of a power line relative to the heading of the aircraft.
  • FIG. 10 illustrates another apparatus for
  • FIGS. 1A and 1B illustrate an on-board
  • electric field detector system 20 for use on board an aircraft to detect an electrical power line P, having an electric field associated therewith.
  • the conductors are spaced apart a distance Z S and located a linear distance Z L above an electrical ground plane which may be located near the earth's surface.
  • the image lines are spaced apart a distance Z S and located beneath the ground plane the same linear distance Z L as the real lines are above the ground plane.
  • the polarity of the image lines is opposite to that of the real lines.
  • ⁇ o the permittivity of free space
  • R the radial distance from the line to the sensor.
  • relative field strengths may be calculated from the geometry of the model by summing the contributions of each conductor, inserting range values and setting the constants for a given power line, i.e. P/(2 ⁇ o ), equal to one.
  • the electric field is directed radially away from the power line.
  • the net electric field at any point of interest is the vector sum of the electric fields from the real three phase power line plus the electric fields from the three image conductors.
  • the fields can be reduced to vertical and horizontal components relative to the earth's surface and the components summed to obtain the net electric field.
  • the net horizontal component is generally different in magnitude from the net vertical component.
  • FIG. 2 illustrates the horizontal and vertical components E H and E V of the electric field
  • the total field may be computed as:
  • the vertical component may be expressed as :
  • E VI E I ⁇ (Z A - Z L )/R I '.
  • E HI E I ⁇ [R + (I - l)Z S ]/R I '.
  • the total field for the image conductors located beneath the ground plane, where I equals four, five or six, may be expressed as:
  • E VI E I ⁇ (Z A + Z L ) /W I ' ' .
  • E HI E I ⁇ [R + (I - 4)Z S )]/R I ''.
  • the total horizontal and vertical fields are the summation of the respective horizontal and vertical contributions of the real conductors and the image conductors, that is from the variable I equals one through I equals six.
  • Various range values were substituted into the above equations and the results are graphed in FIG, 3.
  • detector 20 Referring again to FIG. 1, detector 20
  • sensor means 22 including on-board antenna means, such as antenna 32, for sensing the electric field produced by the electrical power lines P and for producing an electric field signal corresponding to the sensed electric field.
  • Signal processing means 24 are provided for receiving and processing the electric field signal and for producing therefrom an output signal.
  • the output signal is received by output means 26 for providing an output to an operator of the aircraft, such as an aircraft pilot or an autopilot control system, indicative of factors concerning the approach of the aircraft toward the power line P, such as the time-to-impact.
  • the antenna means may comprise one or more of a variety of different antenna arrangements capable of detecting an electric field.
  • an antenna means placed upon a vehicle having a nonconductive body, such as of fiberglass may comprise metallic strips adhered to the body of the vehicle.
  • the antenna means may be mounted on either the interior or the exterior of the vehicle body. Dipole antennas projecting outwardly from the vehicle exterior may also be used.
  • antennas may be mounted to the exterior of the vehicle body. In this case, it is necessary to insulate the antenna from the body, for example by use of an electrically insulating mounting means.
  • the following nomenclature will be used in describing the signals generated by the illustrated embodiment of the emission source detector 20 of the present invention.
  • the subscript letter “H” refers to a horizontal component of the electric field, while the subscript letter “V” refers to a vertical component of the electric field.
  • the letter “E” is used to denote an electric field voltage signal which corresponds to the electric field.
  • the prime symbol (') indicates a sensed voltage representing the composite electric field seen by an antenna means.
  • a double prime symbol ('') or an unprimed variable denotes a signal produced by the signal processing means.
  • One particularly useful antenna means is
  • FIG. 1A for aircraft A having a body of an electrically shielding
  • the sensor means 22 comprises the cross-polarized antenna 32, shown also in FIG. 1B, mounted to the exterior of the body by an electrically insulating means (not shown).
  • Electrical coupling means such as a coaxial cable, interconnect the antenna 32 with the signal processing means 24.
  • An electrical coupling means also interconnect the signal processing means 24 with the output means 26.
  • FIG. 5 illustrates an additional portion of the sensor means 22 comprising signal conditioning means 60 for producing a conditioned electrical field signal output of E H '' or E V '' from the
  • the signal conditioning means 60 have a high input impedance operational amplifier 62 which receives and amplifies an antenna signal, such as E H '.
  • the amplified antenna signal is filtered by a filter 64 to remove frequency components other than the power line frequency and to produce conditioned antenna signals E H ''.
  • the values of C H and C V can be calculated from measured values of E and R. Thus, if ⁇ T is known and ⁇ E H or ⁇ E V is measured, the value of T can be calculated. For example, the signal E H '', which represents the horizontal component of E, is sampled at
  • a range value can be determined.
  • the detector was a simple high input impedance amplifier having an output to a digital voltmeter.
  • the sensor was a dipole antenna, which was held in horizontal and vertical orientations to detect the respective horizontal and vertical components of the electric field at various distances from the power
  • the sensor means 22 comprising the antenna means and the signal conditioning means 60 may be physically concentrated within one area of the aircraft or dispersed in several locations throughout the aircraft.
  • the signal conditioning means 60 may be physically located within the aircraft adjacent the signal processing means 24.
  • the signal conditioning means 60 may be located near the antenna 32.
  • the aircraft heading is not relevant to the time-to-impact calculation since the time-to-impact is dependent only on the range R and the component of the aircraft's ground velocity that is perpendicular to the path of the power line.
  • the heading relative to the direction of the power line is important to a pilot determining in which direction to make a course correction.
  • direction of a power line means the direction of the shortest line from the
  • the direction of the power line relative to the aircraft heading may be determined by use of sensors 30 and 34.
  • Sensors 30 and 34 are mounted at the left and right respectively of the aircraft.
  • FIG. 7A shows two hollow, rectangular metal shells 120 and 122.
  • Shells 120 and 122 are identical.
  • the end faces of the shells are parallel and the shells are attached together by a plate 124 of electrically insulating material, such as the synthetic plastic material sold under the trademark DELRIN.
  • the four side faces of shell 122 are coplanar with respective faces of shell 120.
  • the X, Y and Z dimensions of each shell are about 12.5 cm, 5 cm and 18 cm respectively, and the shells are spaced apart in the X direction by about 6.4 cm.
  • An ammeter 126 is connected to the two shells.
  • the ammeter is shown outside the shells, this is purely for ease of illustration. In fact, the ammeter is inside one of the shells, so that it is shielded from external fields, and its display is observed through a small hole in a face of that shell.
  • the apparatus shown in FIG. 7A is similar to apparatus currently used for
  • the apparatus shown in FIG. 7A was supported above the ground in the vicinity of a three-phase, high voltage electric power line.
  • the apparatus was supported at a height of about 4 m above the ground, in order to minimize ground plane effects.
  • the shells were disposed with the XZ plane
  • the ammeter which is of very low impedance, provides the only path for current to flow between the two shells and the charges on the two shells are redistributed through the ammeter.
  • the ammeter provided a measurable current reading.
  • the apparatus was then rotated through 180 degrees about a vertical axis, so that the positions of the shells relative to the power line were reversed, but the two shells stayed in the same positions relative to each other. The ammeter reading was found not to be significantly different from the previous ammeter reading.
  • FIG. 7B A similar experiment to that described with reference to FIG. 7A was conducted using the apparatus shown in FIG. 7B.
  • the apparatus shown in FIG. 7B is the same as that shown in FIG. 7A, except that the Z dimension of one of the shells is about 36 cm instead of about 18 cm. It was found that when the smaller shell was closer to the power line, the ammeter reading was about twice that when the larger shell was closer to the power line.
  • each of the sensors 30 and 34 is a rectangular shell.
  • Sensors 30 and 34 are mounted to opposite respective sides of the central plane of the aircraft ,i.e., the plane through the central axis of the aircraft and about which the aircraft is substantially symmetrical, with the YZ plane (FIG. 7A) parallel to the central plane of the aircraft.
  • Sensors 30, 34 are mounted by use of insulating material and are electrically connected to the metal aircraft body through respective ammeters 128, 130 (FIG. 8).
  • the metal aircraft body then functions as a large shell relative to the smaller shells of sensors 30, 34.
  • the current between sensor 30 and the aircraft body will be larger than the current between sensor 34 and the aircraft body if the direction of the power line is to the left of the aircraft, and vice versa when the direction of the power line is to the right of the aircraft.
  • Ammeters 128, 130 generate voltage signals proportional to the respective current values, these signals are applied to a comparator 132 and the result of the comparison is used to indicate the direction of the power line.
  • FIG. 6 illustrates hardware 70 used to process the conditioned antenna signals.
  • the conditioned antenna signal outputs from filter 64 of the sensor means 22 are supplied as the conditioned analog E field sensor inputs to an analog-to-digital converter 72.
  • the voltage signals representative of the currents measured by ammeters 128, 130 are applied to analog-to-digital converter 72 instead of to comparator 132.
  • Converter 72 converts its input signals into digital signals which are supplied to a central bus 74.
  • the signal processing means 24 includes a central processor unit (CPU) 80, memory means 82, data input device such as a touch pad 84, and visual output device such as a CRT monitor 86.
  • CPU central processor unit
  • the central processor unit 80 includes interacting bus control means 88, arithmetic means such as an arithmetic unit 90, flags 92, a stack pointer 94, a program counter 96, and storage registers 98.
  • the memory means includes various memory units, such as random access memory (RAM), read-only memory (ROM) , and electrically erasable and
  • the visual output device 86 and the data input device 84, such as a keyboard, may be of the type typically used with personal computers.
  • the output means 26 in communication with central bus 74 include an audible warning device 100.and a visual line location indicator 102, which communicates with central bus 74 through a digitalto-analog (D/A) converter 104.
  • the audible warning device 100 which may include a speech synthesizer, provides an output to a loudspeaker or other electroacoustic transducer 106 to alert the pilot of an upcoming power line.
  • the visual line indicator 102 provides an output to the pilot which indicates the direction of an upcoming power line relative to the aircraft heading.
  • the visual line indicator may take on any form, such as three lights or lightemitting diodes (LEDs) 108.
  • the visual output device 86 provides a legible readout of the result of the time-to-impact calculation.
  • FIG. 9 illustrates an aircraft having a bubble 140 of insulating material projecting beneath the aircraft body, which is typically metal.
  • apparatus 142 for detecting the direction of a power line.
  • This apparatus is similar to the apparatus described with reference to FIG. 7B , and comprises two different-sized metal shells 144, 146 connected to an ammeter 148 and mounted on an insulating plate 150 so that the only current path between the shells is through the ammeter.
  • the shells are supported so that they can be rotated continually relative to the aircraft about an axis perpendicular to the open ends of the shells without changing the orientation of the shells relative to each other.
  • the shaft is provided with an angle encoder 156 which indicates the angular position of the shells relative to the central axis of the aircraft. Both the ammeter and the angle encoder are connected to a computer 160.
  • the current flowing through the ammeter will vary with a frequency equal to the rotational frequency of shaft 154.
  • the computer detects the positive and negative peaks of the periodic variation in the current and relates it to the azimuth signal provided by the angle encoder.
  • the computer then provides an output signal indicating the direction of the power line relative to the central axis of the aircraft so as to enable the pilot to change the heading of the aircraft in a manner that will avoid impact with the power line.
  • FIG. 10 illustrates in plan view another form of apparatus for detecting the direction of a power line.
  • the apparatus shown in FIG. 10 comprises a pair of identical sensors 180, 182 mounted at opposite respective wing tips of an aircraft.
  • the antennas are about 7-10 m apart.
  • Each sensor is composed of a metal shell similar to shell 144 and is mounted on the aircraft wing, if it is made of metal, in electrically insulating fashion and in an orientation such that the X axis is parallel to the central axis of the aircraft.
  • Respective ammeters are connected between the sensors and the respective aircraft wings, to measure the redistribution of charge between each sensor and the aircraft body, in similar fashion to that described with reference to FIG. 8.
  • the currents measured by the two ammeters will be equal, whereas if the aircraft is not heading directly towards the power line, the current measured by the ammeter connected to the sensor that is closer to the power line will be larger than the current measured by the other ammeter.
  • the values of the currents measured by the respective ammeters are compared in order to provide an indication as to the direction of the power line relative to the aircraft heading, i.e., whether the power line is straight ahead of the aircraft, to the left or to the right.
  • FIG. 9 may be applied to a helicopter by mounting the sensors on the rotor tips.

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  • Physics & Mathematics (AREA)
  • Electromagnetism (AREA)
  • General Physics & Mathematics (AREA)
  • Geophysics And Detection Of Objects (AREA)
  • Traffic Control Systems (AREA)

Abstract

Un détecteur pour l'utilisation à bord d'un avion se dirigeant le long d'une trajectoire permettant de détecter une ligne électrique (P) comprend une antenne (32) pour détecter le champ électrique associé à la ligne électrique et produire un signal de champ électrique (EH', EV'), un processeur de signaux (24) pour recevoir le signal du champ électrique et générer un signal représentant le temps restant jusqu'à l'impact, c'est à dire le temps qu'il faut pour que l'avion atteigne la ligne électrique s'il continue sur sa trajectoire. Des détecteurs (30, 34, 180 182) sont utilisés pour détérminer la direction de la ligne électrique.
PCT/US1990/003374 1989-06-28 1990-06-13 Systeme de detection de champ electrique WO1991000525A1 (fr)

Applications Claiming Priority (4)

Application Number Priority Date Filing Date Title
US37380589A 1989-06-28 1989-06-28
US373,805 1989-06-28
US47854790A 1990-02-12 1990-02-12
US478,547 1990-02-12

Publications (1)

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WO1991000525A1 true WO1991000525A1 (fr) 1991-01-10

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CA (1) CA2032165A1 (fr)
WO (1) WO1991000525A1 (fr)

Cited By (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP0515266A1 (fr) * 1991-05-23 1992-11-25 Application Securite Positive Asept S.A. Détecteur de proximité de lignes électriques aériennes
FR2784754A1 (fr) * 1998-09-18 2000-04-21 Safe Flight Instrument Systeme de detection et d'avertissement de la presence d'une ligne electrique pour un aeronef
EP1831704A4 (fr) * 2004-12-23 2015-07-15 Power Survey Llc Detecteur permettant de detecter un champ electrique
EP3767229A1 (fr) * 2005-10-19 2021-01-20 Osmose Utilities Services, Inc. Appareil et procédé de détection d'anomalies de tension parasite
CN118226140A (zh) * 2024-05-27 2024-06-21 浙江安联检测技术服务有限公司 一种工频电场测量装置

Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2454630A (en) * 1945-01-08 1948-11-23 United Air Lines Inc Method and apparatus for indicating potential gradients
US2969539A (en) * 1958-03-28 1961-01-24 Bosch Arma Corp Proximity warning and collision avoidance system
US4013955A (en) * 1975-07-02 1977-03-22 The United States Of America As Represented By The Secretary Of The Navy Analog signal processor
US4199715A (en) * 1974-11-15 1980-04-22 The Johns Hopkins University Method and apparatus for defining an equipotential line or _surface in the earth's atmosphere and measuring the misalignment of a _selected line or plane relative to an equipotential line or surface

Patent Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2454630A (en) * 1945-01-08 1948-11-23 United Air Lines Inc Method and apparatus for indicating potential gradients
US2969539A (en) * 1958-03-28 1961-01-24 Bosch Arma Corp Proximity warning and collision avoidance system
US4199715A (en) * 1974-11-15 1980-04-22 The Johns Hopkins University Method and apparatus for defining an equipotential line or _surface in the earth's atmosphere and measuring the misalignment of a _selected line or plane relative to an equipotential line or surface
US4013955A (en) * 1975-07-02 1977-03-22 The United States Of America As Represented By The Secretary Of The Navy Analog signal processor

Cited By (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP0515266A1 (fr) * 1991-05-23 1992-11-25 Application Securite Positive Asept S.A. Détecteur de proximité de lignes électriques aériennes
FR2676824A1 (fr) * 1991-05-23 1992-11-27 Asept Applic Securite Positive Detecteur de proximite de lignes electriques aeriennes.
FR2784754A1 (fr) * 1998-09-18 2000-04-21 Safe Flight Instrument Systeme de detection et d'avertissement de la presence d'une ligne electrique pour un aeronef
EP1831704A4 (fr) * 2004-12-23 2015-07-15 Power Survey Llc Detecteur permettant de detecter un champ electrique
EP3767229A1 (fr) * 2005-10-19 2021-01-20 Osmose Utilities Services, Inc. Appareil et procédé de détection d'anomalies de tension parasite
CN118226140A (zh) * 2024-05-27 2024-06-21 浙江安联检测技术服务有限公司 一种工频电场测量装置

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AU6043990A (en) 1991-01-17
CA2032165A1 (fr) 1990-12-29

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