EP0855019A1 - Mesure a distance de temperatures internes a travers un materiau permeable a un rayonnement a hyperfrequence - Google Patents

Mesure a distance de temperatures internes a travers un materiau permeable a un rayonnement a hyperfrequence

Info

Publication number
EP0855019A1
EP0855019A1 EP96933287A EP96933287A EP0855019A1 EP 0855019 A1 EP0855019 A1 EP 0855019A1 EP 96933287 A EP96933287 A EP 96933287A EP 96933287 A EP96933287 A EP 96933287A EP 0855019 A1 EP0855019 A1 EP 0855019A1
Authority
EP
European Patent Office
Prior art keywords
internal temperatures
temperatures according
measuring internal
remotely measuring
remotely
Prior art date
Legal status (The legal status 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 status listed.)
Withdrawn
Application number
EP96933287A
Other languages
German (de)
English (en)
Inventor
Khaled Abdolall
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Powertech Labs Inc
Original Assignee
Powertech Labs Inc
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 Powertech Labs Inc filed Critical Powertech Labs Inc
Publication of EP0855019A1 publication Critical patent/EP0855019A1/fr
Withdrawn legal-status Critical Current

Links

Classifications

    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01K—MEASURING TEMPERATURE; MEASURING QUANTITY OF HEAT; THERMALLY-SENSITIVE ELEMENTS NOT OTHERWISE PROVIDED FOR
    • G01K11/00—Measuring temperature based upon physical or chemical changes not covered by groups G01K3/00, G01K5/00, G01K7/00 or G01K9/00
    • G01K11/006—Measuring temperature based upon physical or chemical changes not covered by groups G01K3/00, G01K5/00, G01K7/00 or G01K9/00 using measurement of the effect of a material on microwaves or longer electromagnetic waves, e.g. measuring temperature via microwaves emitted by the object

Definitions

  • the present invention relates to remotely determining internal temperatures through materials penetrable by microwave radiation using microwave radiometric techniques . More specifically the present invention relates to monitoring porcelain and polymer clad high voltage equipment. The present invention also relates to detection of forest fires and locating persons in search and rescue operations, and law enforcement operations.
  • High voltage equipment failure is a major component in the maintenance costs of electrical transmission and distribution systems.
  • Such equipment includes: protective devices such as surge arrestors, current transformers, potential transformers, capacitance voltage transformers (CVT's) and potheads.
  • protective devices such as surge arrestors, current transformers, potential transformers, capacitance voltage transformers (CVT's) and potheads.
  • CVT's capacitance voltage transformers
  • potheads In most of this equipment porcelain or polymer insulators are used for housing the insulation system or the active elements of a protective device.
  • Many equipment failures can be attributed to failure of the insulation system of transformers and capacitors, or the active elements of protective devices. The failures are usually due to incipient faults that develop over a period of time, and are frequently accompanied by partial discharge and localized heating. Thus, there is a need to monitor and determine internal temperatures of the equipment to determine the general condition.
  • the present invention provides a non-invasive method and a system for remotely measuring internal temperature of porcelain and polymer clad devices.
  • the present invention also relates to detection of forest fires and locating persons in search and rescue operations, and law enforcement operations. By being able to monitor internal temperatures remotely avoids the necessity of having to approach and contact each device. One cannot approach and contact high voltage equipment without shutting off the power, thus causing power interruptions to the end user.
  • An example of a need to determine internal heat through materials would be buildings, enabling one to determine whether there is a location of high temperature within a building which might indicate a fire.
  • forest fires or hot spots i.e., kindling sites
  • Another use for determining hot internal temperatures is search and rescue operations, such as locating persons in collapsed buildings after earthquakes, bombing or other collapses, locating persons buried by avalanches, landslides and other disasters.
  • Another use of the present invention is to remotely scan in medical treatment for hypothermia conditions to determine internal temperature of the different body organs, also to locate cancerous tumours within a body. In each case the locations of higher thermal radiation can be determined.
  • Yet a further use of the present invention is detection of forest fires and locating people in search and rescue and law enforcement operations.
  • Still further uses of the present invention include measuring temperatures of chemical reactions in corrosive environments, measuring temperature of hazardous materials and infectious waste materials during destruction processes.
  • the present invention provides a method of remotely measuring internal temperatures through materials penetrable by microwave radiation, comprising the steps o : selecting a frequency range where the microwave radiation at least partially penetrates the materials; detecting self emitted thermal radiation through the materials for the microwave frequency range in a target beam of a passive receiver; producing signals proportional to the thermal radiation detected in the target beam; remotely scanning the target beam of the passive receiver through a target pattern; comparing the signals for different locations in the target pattern to identify locations emitting higher thermal radiation, and processing the signals to provide an indication of internal temperature for the locations emitting higher thermal radiation.
  • the present invention also provides a device for remotely measuring internal temperatures through materials penetrable by microwave radiation comprising: a passive receiver to detect thermal radiation for a predetermined microwave frequency range in a target beam; scanning means for the receiver to remotely scan the target beam through a target pattern, such that the receiver produces signals proportional to the thermal radiation through the materials in different locations of the target pattern, and comparative means to compare the signals from the different locations as the target beam scans to produce an indication of temperature differences in the different locations.
  • Figure 1 is a schematic drawing of a typical measurement set up for detection of internal hot spots showing a passive microwave radiometer according to one embodiment of the present invention with a target beam from an antenna,
  • FIG. 2 is a block diagram of a passive receiver radiometer according to one embodiment of the present invention.
  • Figure 3 is an isometric view showing a mounting and scanning arrangement for a passive microwave radiometer according to one embodiment of the present invention
  • Figure 4 is a graph showing temperature difference in vertical distance for a porcelain column containing a string of silicon carbide blocks with two heated elements therein,
  • Figure 5 is a graph showing temperature difference in vertical distance for a porcelain column containing a string of zinc oxide blocks with two heated elements therein
  • Figure 6 is a graph showing temperature difference in vertical distance for a porcelain column containing heated oil/paper insulation therein
  • Figure 7 is a graph showing radiometric temperature as a function of physical temperature of zinc oxide blocks
  • Figure 8 is a graph showing radiometric temperature as a function of physical temperature of silicon carbide blocks
  • Figure 9 is a thermal image representing temperature gradients for a target pattern
  • Figure 10 is a thermal profile of a test of burning charcoal covered by forest duff
  • Figure 11 is a thermal image of a person behind a wall taken from about 10 metres.
  • a scanning device is illustrated in Figure 1 having a microwave radiometer 10 attached to the back of a dish antenna 12 having an antenna pattern 14 as illustrated.
  • a narrow target beam 16 represents the antenna receiving beam in which the passive receiver 10 detects thermal radiation.
  • the beam 16 is shown aimed at an insulator 18 formed of porcelain or polymer which has inside it a series of metal oxide or silicone carbide blocks 20 to absorb excess energy. These blocks absorb energy from lightning strikes and other electrical surges and thus heat up.
  • a laser pencil 22 Positioned at the center of the antenna dish 12 is a laser pencil 22 which projects a coloured laser beam onto the surface of the insulator 18.
  • the laser beam 24 provides a pin point light on the surface to enable an operator to aim the narrow target beam 16 and ensure it is directed at the insulator 18. By moving the antenna 12 the laser beam 24 also moves so the pin point light changes position on the insulator 18 and this is visible from a considerable distance.
  • a laser pencil 22 and laser beam 24 are shown as being one system for aiming or positioning the antenna 12, other aiming devices such as a sighting telescope may also be provided so an operator knows the exact location where the narrow beam 16 is observing.
  • insulator 18 shows an insulator 18, however, this could be a building with walls of wood, concrete or other materials that permit at least partial penetration of microwaves.
  • insulator 18 In the measurement of internal temperature, it is necessary to compare the temperature of one target location with other locations in a general target pattern on the insulator or the like. Thus, a scanning action occurs across different locations to determine temperatures at each of these locations. The locations that do not have internal heat points can be compared with locations that do have internal heat points.
  • the radiometer 10 By scanning the beam up and down or sideways over an insulator 18, then the radiometer 10 initially detects the temperature of the porcelain insulator at the location where there is no internal hot spots, but as the scan progresses, the target beam is aimed at the heated blocks 20 within the insulator 18 and an increase in thermal radiation is detected.
  • the radiometer 10 as shown in more detail in Figure 2 is of the type known as a Dicke radiometer known in the prior art and specific reference is made to this type of radiometer in a textbook entitled "Microwave Remote Sensing Active and Passive” by Ulaby et al, Volume 1, Artech House, Norwood, published 1981.
  • the antenna 12 detects thermal radiation in the microwave frequencies.
  • the antenna is a parabolic dish antenna with a center frequency of 17 GHz, 36" diameter feed type Cassegrain, a gain of 40 dB minimum and a maximum beam width not more than 1.4° at the 3 dB level.
  • the signal from the antenna is modulated by a ferrite Dicke switch with driver 32.
  • the modulation consists of periodically switching the receiver input between the antenna 12 and a constant reference noise temperature source 36 at a switching rate higher than the highest significant spectral component in the gain variation spectrum.
  • a switching frequency of 98.2 Hz was chosen so that over a period of one cycle the system gain is essentially constant, and therefore identical for the half cycle to which the receiver is connected to the antenna 12 and the half cycle when the receiver is connected to the reference source 36.
  • the components of the radiometer 10 were mounted on aluminum plate attached to the antenna 12 as shown in Figure 1.
  • the radiometer 10 is enclosed in a thermally insulated constant temperature enclosure 38 maintained at /14941
  • thermoelectric cooler 40 20.5°C within 0.01°C by means of a thermoelectric cooler 40.
  • a small fan (not shown) mounted inside the enclosure keeps the air temperature uniform.
  • the temperature of the reference source 36 was controlled by means of a heating jacket 42 surrounding the termination.
  • the heating jacket 42 was insulated and the temperature of the reference termination was maintained stable within 0.01°C.
  • null balancing is achieved by noise injection from a noise diode 43 into the antenna signal through a cross arm directional coupler 44 in the form of narrow pulses controlled by the PIN switch 46 via the feedback circuit.
  • the integrator 48 and feedback amplifier 50 drive a voltage controlled oscillator 52 which in turn drives a pulse generator 54 which drives the PIN switch 46.
  • the switching frequency is controlled by the feedback loop to provide the necessary amount of noise that a null condition is maintained at the input of the integrator 48.
  • the frequency of the pulses is linearly related to the antenna temperature.
  • the radiometer 10 has a first low noise amplifier 56 operating within a frequency of 16-18 GHz, a pass band filter 58 having a center frequency of 17 GHz with a band width of 2 ⁇ 0.2 GHz.
  • the filter takes out all signals outside the 16 to 18 GHz range and thus is a preferred range for determining internal temperatures of porcelain and polymer clad devices.
  • the filtered signal is further amplified by a second stage low noise amplifier 60 and detected by a crystal detector 62 which provides an output signal that is fed through a synchronous demodulator 64 modulated at the switching frequency of the Dicke switch 32.
  • a frequency counter 66 such as a monitoring screen or other visual indication system displays the thermal radiation.
  • Other techniques may be used to continuously maintain a Dicke radiometer in a balanced state including reference channel control, antenna channel noise injection and gain modulation.
  • the scanning mechanism is shown in more detail in Figure 3.
  • the antenna 12 and radiometer 10 are mounted on an H-frame 60.
  • a worm gear arrangement 62 joined to a mounting bracket 64 for scanning in a vertical direction and a rotary arrangement 66 rotates the mounting bracket 64 on the H-frame 60 in a horizontal plane.
  • the laser pencil 22 is used for aiming the antenna.
  • the post processing and display 68 permits areas of higher thermal radiation to be seen in the form of graphs, contour plots or thermal image pictures.
  • a first motor 70 drives the worm gear arrangement 62 and a second motor 72 drives the rotary arrangement 66.
  • a computer 74 associated with the post processing and display 68 provides signals for the antenna 12 to scan through a predetermined pattern.
  • Processing of the signals are then arranged to provide a pattern image on a screen so that areas that emit higher thermal radiations are displayed.
  • the spatial resolution of this technique is determined mainly by the beam width of the antenna.
  • the beam width is a function of the aperture size and frequency.
  • the system was optimized for detecting hot spots within porcelain clad devices and the operating frequency was chosen so that losses within the porcelain do not present a problem using a reasonable size antenna with good spatial resolution.
  • the microwave radiation would be more penetrating over a wider frequency range and smaller size antenna may be used.
  • the radiometer was operated in the 16 to 18 GHz having a center frequency of 17 GHz and a modulation frequency of 98.2 Hz.
  • ⁇ T (Dicke mode) is 0.027°C for 100 msec integration time
  • ⁇ T (nulling mode) is 0.022°C for 200 msec feedback loop time constant.
  • the antenna was a Cassegrain type with an aperture of 36" and a beam width less than 1.4° and a gain of 40 dB.
  • Tests were carried out on zinc oxide surge arrester blocks, silicon carbide surge arrester blocks and paper/oil insulation. The measurements were carried out with the radiometer operating in the Dicke mode and in the nulling mode. The measurements were also carried out with lights on and lights off to examine the effects of reflection and background radiation. In the balance mode the reference temperature is always higher than the temperature of the scene, therefore T ref - T A gets smaller near the hot spot, whereas in the unbalanced mode T A - T re£ gets larger near the hot spot.
  • Figure 4 shows the response of the radiometer in an unbalanced state looking at a porcelain column containing a string of silicon carbide blocks with two elements heated electrically and the room lights on.
  • the first and lowest temperature is the room temperature and represents no electric heating.
  • Figure 5 shows the response of a balanced radiometer looking at a porcelain column containing a string of zinc oxide blocks with two of the blocks heated electrically and the lights on.
  • Figure 6 shows the response of a balanced radiometer looking at a porcelain column containing oil/paper insulations heated electrically.
  • Figures 7 and 8 show the temperature dependence of the radiometric temperature for zinc oxide and silicon carbide blocks.
  • the materials show a non-linear behaviour making the materials radiometrically more visible at higher temperature. This phenomenon enhances the sensitivity of the technique to zinc oxide or silicon carbide malfunction.
  • Figure 9 shows a two dimensional thermal image illustrating contour plot of the internal temperature of a 500 kV current transformer. The intensity readings are shown with the lightest or white area representing the hot area and the darkest or black representing the coolest area.
  • the two dimensional plan represents linear units for width and height.
  • microwave radiometric techniques for remote measurement of internal temperatures of porcelain and polymer clad devices are successful since radiation at microwave frequencies can penetrate moderately lossy materials, thus internal temperatures can be determined by measuring the emitted microwave power through the lossy materials.
  • a portable radiometer with small dish antenna or a phaser ray can be used with a sighting device such as a laser pencil permitting an operator to move the antenna by hand scanning backward and forward to determine hot spots in an insulator or other object that has penetrable materials in front thereof.
  • the scanning mechanism scans in a predetermined pattern which is recorded and provides an image of higher thermal readings at specific locations in the pattern.
  • the device for measuring internal temperatures is for insulators, it will be apparent to those skilled in the art that this system would equally well apply for determining the presence of, for example, a person within a building, for locating individuals buried by fallen buildings caused by earthquakes, bombing incidents or collapse of buildings, and to locate fires within buildings.
  • the antenna may be mounted in an aircraft for scanning forests to determine hot spots with a mechanical and/or electronic scanning system linked to a computer to provide exact locations where hot spots occur.
  • the radiometer also has uses in the medical field. A hand held radiometer may be used for scanning and a pin point positioner used to locate an area of increased thermal radiation within the body.
  • Underground or unseen forest fires can be detected remotely by scanning in the frequency range from about 0.5 GHz to 16 GHz.
  • the device for remotely scanning may be hand held or mounted on a vehicle or in an aircraft. When mounted in an aircraft the microwave frequency can be in the range of about 0.5 GHz to 40 GHz. In this latter case the device may also be positioned on a mountain top or on top of an observation tower to constantly monitor forest fires.
  • Figure 10 illustrate an example of use of the device. The graph illustrates the thermal profile of burning charcoal covered with forest duff so the hot spot cannot be seen. This profile was obtained from the device positioned 10 metres away. The position figures are linear units.
  • the device for remotely measuring internal temperatures through materials penetrable by microwave radiation is used for locating people inside buildings and houses.
  • the device may be used for law enforcement, search and rescue operations.
  • the device may be hand held or mounted in a vehicle or aircraft, the preferred frequency range is from about 0.5 GHz to 16 GHz.
  • Figure 11 illustrates the image obtained by the device of a person which is seen through a drywall.
  • a target pattern produces a thermal image of a house or building and can detect a fire.
  • the device also can determine the extent of the fire. Hot spots in walls, ceilings of houses and buildings, due to electrical faults or excess heat produced in heating or ventilating equipment.
  • Security of buildings may also be monitored by the device of the present invention.
  • the presence of intruders or burglars behind walls can be detected by scanning in the frequency range of about 0.5 GHz to 16 GHz.
  • the present invention discloses detecting with a single target beam and scanning the target beam through a target pattern.
  • a plurality of phase arrays or multiple detectors and antennas pointed in a series of different target beams to form a target pattern are provided.
  • the scanning arrangement which moves either a single or multiple detectors to see different parts of the scene to create real time images in the form of pictures.
  • the frequency is dependent partly upon the materials to be penetrated by microwave radiation for determining internal temperature and partly by the distance, range and required spatial resolution. For example, if the radiometer were used on a human body, then a small diameter antenna would be used.

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  • Physics & Mathematics (AREA)
  • Electromagnetism (AREA)
  • General Physics & Mathematics (AREA)
  • Radiation Pyrometers (AREA)
  • Geophysics And Detection Of Objects (AREA)

Abstract

L'invention porte sur un procédé permettant de mesurer à distance des températures internes à travers des matériaux perméables à un rayonnement à hyperfréquence ainsi que sur l'appareil correspondant. Il est, de la sorte, possible de détecter des secteurs à températures supérieures, dans un équipement haute tension par exemple, à travers des isolants gainés de porcelaine alors que la plupart des systèmes de détection ne prennent de mesures que de la surface externe. Ce procédé consiste à sélectionner une plage de fréquence dans laquelle le rayonnement à hyperfréquence pénètre au moins partiellement dans les matériaux, à détecter un rayonnement thermique auto-émetteur à travers ces matériaux pour la plage de fréquence à hyperfréquence dans un faisceau cible d'un receveur passif, à produire des signaux proportionnels au rayonnement thermique décelé dans le faisceau cible, à analyser à distance le faisceau du receveur passif selon un diagramme cible, à comparer les signaux relatifs à différents emplacements dans le diagramme cible afin d'identifier les emplacements d'émission d'un rayonnement supérieur et à traiter les signaux pour fournir une indication concernant une température interne relative aux emplacements d'émission de rayonnements thermiques supérieurs.
EP96933287A 1995-10-13 1996-10-11 Mesure a distance de temperatures internes a travers un materiau permeable a un rayonnement a hyperfrequence Withdrawn EP0855019A1 (fr)

Applications Claiming Priority (3)

Application Number Priority Date Filing Date Title
US542677 1983-10-17
US54267795A 1995-10-13 1995-10-13
PCT/CA1996/000686 WO1997014941A1 (fr) 1995-10-13 1996-10-11 Mesure a distance de temperatures internes a travers un materiau permeable a un rayonnement a hyperfrequence

Publications (1)

Publication Number Publication Date
EP0855019A1 true EP0855019A1 (fr) 1998-07-29

Family

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Family Applications (1)

Application Number Title Priority Date Filing Date
EP96933287A Withdrawn EP0855019A1 (fr) 1995-10-13 1996-10-11 Mesure a distance de temperatures internes a travers un materiau permeable a un rayonnement a hyperfrequence

Country Status (4)

Country Link
EP (1) EP0855019A1 (fr)
AU (1) AU2280897A (fr)
CA (1) CA2234584C (fr)
WO (1) WO1997014941A1 (fr)

Families Citing this family (7)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP1944591A1 (fr) * 2007-01-10 2008-07-16 Nederlandse Organisatie voor toegepast-natuurwetenschappelijk Onderzoek TNO Procédé et dispositif de détection des sources de chaleur
US8049620B2 (en) 2007-06-15 2011-11-01 Icove And Associates, Llc Passive microwave fire and intrusion detection system including black body and spectral emission at the hydrogen, hydroxyl and hydrogen chloride lines
US8044798B2 (en) 2007-06-15 2011-10-25 Icove And Associates, Llc Passive microwave speed and intrusion detection system
US7724134B2 (en) 2007-06-15 2010-05-25 Icove And Associates, Llc Passive microwave fire and intrusion detection system
US8493212B2 (en) 2007-06-15 2013-07-23 Icore and Associates, LLC Passive microwave system and method for protecting a structure from fire threats
EP2073037A1 (fr) 2007-12-21 2009-06-24 Nederlandse Organisatie voor toegepast-natuurwetenschappelijk Onderzoek TNO Détection d'objets cachés grâce aux ondes électromagnétiques
CN103985218B (zh) * 2014-05-16 2016-10-26 中国矿业大学 矿井隐蔽火灾危险电磁辐射探测装置及方法

Family Cites Families (4)

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Publication number Priority date Publication date Assignee Title
US3777270A (en) * 1972-05-12 1973-12-04 Rockwell International Corp Precision variable pulse rate nulling radiometer
DE2803480C2 (de) * 1978-01-27 1984-11-22 Philips Patentverwaltung Gmbh, 2000 Hamburg Verfahren und Anordnung zur Messung der physikalischen Objekttemperatur mittels Mikrowellen
JPS6022636A (ja) * 1983-07-19 1985-02-05 Daido Gakuen 物体の温度を測定する方法および装置
JPH0215397A (ja) * 1988-07-01 1990-01-19 Daido Gakuen 火災検知装置

Non-Patent Citations (1)

* Cited by examiner, † Cited by third party
Title
See references of WO9714941A1 *

Also Published As

Publication number Publication date
CA2234584C (fr) 2005-08-02
CA2234584A1 (fr) 1997-04-24
WO1997014941A1 (fr) 1997-04-24
AU2280897A (en) 1997-05-07

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