WO1997022012A1 - Voltmetre electro-optique - Google Patents

Voltmetre electro-optique Download PDF

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Publication number
WO1997022012A1
WO1997022012A1 PCT/US1996/019346 US9619346W WO9722012A1 WO 1997022012 A1 WO1997022012 A1 WO 1997022012A1 US 9619346 W US9619346 W US 9619346W WO 9722012 A1 WO9722012 A1 WO 9722012A1
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WO
WIPO (PCT)
Prior art keywords
sensor
conductor
voltage
sensor head
field
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.)
Ceased
Application number
PCT/US1996/019346
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English (en)
Inventor
Gregory K. Woods
Todd W. Renak
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.)
Lockheed Idaho Technologies Co
Original Assignee
Lockheed Idaho Technologies Co
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
Priority claimed from US08/569,338 external-priority patent/US5892357A/en
Priority claimed from US08/570,152 external-priority patent/US5731579A/en
Application filed by Lockheed Idaho Technologies Co filed Critical Lockheed Idaho Technologies Co
Priority to CA002239722A priority Critical patent/CA2239722C/fr
Priority to EP96944754A priority patent/EP0866975A4/fr
Priority to JP52210397A priority patent/JP2001526770A/ja
Priority to AU13291/97A priority patent/AU1329197A/en
Publication of WO1997022012A1 publication Critical patent/WO1997022012A1/fr
Anticipated expiration legal-status Critical
Ceased legal-status Critical Current

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Classifications

    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01R—MEASURING ELECTRIC VARIABLES; MEASURING MAGNETIC VARIABLES
    • G01R1/00—Details of instruments or arrangements of the types included in groups G01R5/00 - G01R13/00 and G01R31/00
    • G01R1/02—General constructional details
    • G01R1/06—Measuring leads; Measuring probes
    • G01R1/067—Measuring probes
    • G01R1/07—Non contact-making probes
    • G01R1/071—Non contact-making probes containing electro-optic elements

Definitions

  • the Field of the Invention pertains generally to the field of voltage sensors and more particularly to a voltage sensor system which utilizes the Pockels electro-optic effect to measure voltage.
  • High-accuracy measurement of high voltage has traditionally been accomplished using iron-core ferro ⁇ magnetic potential transformers. These devices have substantially limited dynamic range, bandwidth, linearity, and electrical isolation. During electrical fault conditions these transformers can conduct dangerous levels of fault energy to downstream instrumentation and personnel, posing an additional liability.
  • a variety of optic sensors for measuring voltage have been developed in attempts to offer the power industry an alternative to the conventional transformer technology. Generally, these voltage sensor systems require that direct electrical contact be made with the energized conductor. This contact is made necessary by the use of a voltage divider which is utilized to connect the sensing element with the energized conductor on which a measurement is to be made. Direct electrical contact with the conductor may alter or interrupt the operation of the power system by presenting a burden or load.
  • prior art voltage sensor systems are typically bulky, particularly in extremely high voltage applications. This is true because the size of the voltage divider required is proportional to the voltage being measured. The size of such systems can make them difficult and expensive to install and house in substations.
  • interferometric modulation is extremely temperature sensitive. This temperature sensitivity requires controlled conditions in order to obtain accurate voltage measurements. The requirement of controlled conditions limits the usefulness of such systems and makes them unsuited for outdoor or uncontrolled applications.
  • interferometric modulation requires a highly coherent source of electromagnetic radiation, which is relatively expensive.
  • Open-air E-field based sensors have also been developed, but lack accuracy when used for measuring voltage because the open-air E-field used varies with many noisy parameters including ambient dielectric constant, adjacent conductor voltages, moving conductive structures such as passing vehicles, and other electromagnetic noise contributions.
  • Electro-Optical Voltage Sensor System whereby one may measure the voltage difference (or electrical potential difference) between objects or positions Voltage is a function of the electric field (hereinafter "electric field” shall be indicated “E-field") and the geometries, compositions and distances of the conductive and insulating matter.
  • E-field electric field
  • a voltage measurement can be calculated.
  • the invention employs a transmitter, a sensor, a detector, and a signal processor
  • the transmitter produces a beam of electromagnetic radiation which is routed into the sensor
  • this electromagnetic radiation used m the present invention can comprise any wavelengths beyond the visible spectrum, the term
  • the beam undergoes polarization before it undergoes an electro-optic effect m transducer material which is included in the sensor.
  • the light In the polarized beam, the light has at least two components which propagate along at least two orthogonal axes, thus forming at least two orthogonal planes within the beam.
  • the electro-optic effect occurs when the sensor, and m particular the transducer material, is placed m an E- field, and is observable as a differential phase shift of the orthogonal beam components (the two components are shifted m opposite directions) .
  • the planes of propagation are the object of the differential phase shift, also called phase modulation
  • the differential phase shift causes a corresponding change m the beam's polarization
  • the polarization change is m turn converted into a set of amplitude modulated (AM) signals of opposing polarity that are transmitted out of the sensor
  • the detector converts the set of optical AM signals into electrical signals from which the voltage is determined by the signal processor.
  • the sensor processes the beam by splitting the beam m accordance with the components of the orthogonal polarization planes into at least two AM signals
  • these AM signals are then converted into digital signals, fed into a digital signal processor and mathematically processed into a signal proportional to the voltage which produced the E-field.
  • the beam is routed through the transducer material along an initial axis and then reflected by a retroreflector back along a second axis generally parallel to the initial axis.
  • FIG 1 is a diagram of the electro-optical voltage sensor system shown m a generalized high voltage application scenario The diagram was made in accordance with the principles of the present inventio .
  • FIG. 2 is a diagram of an alternative embodiment of the electro-optical voltage sensor system (m the same generalized application scenario) made m 6 accordance with the principles of the present invention.
  • FIG. 3 is a diagram of the light polarizing beam splitter of FIGS. 1 and 2.
  • FIG. 4 shows a partially sectioned side view of a collimator of FIG. 2 and also FIGS 7 and 8, below.
  • FIG. 5 is a diagram of one embodiment of tne transducer of FIGS. 1 and 2, wherein transducing material m only one orientation is shown.
  • FIG. 6 is a diagram of one embodiment of the transducer in FIGS. 1 and 2, wherein transducing material m two orientations is shown.
  • FIG. 7a is a top-down schematic view of one embodiment of the sensor head of FIG. 2.
  • FIG. 7b is a top-down schematic view of one embodiment of the sensor head of FIG. 2.
  • FIG. 7c is a top-down schematic view of one embodiment of the sensor head of FIG. 2.
  • FIG 8 is a top-down schematic view of one embodiment of the sensor head of FIG. 1.
  • FIG. 9 is a cross-sectional, schematic view of one embodiment of the E-field originator of FIGS. 1 and 2, as a shielded joint.
  • FIG. 10 is a top perspective, partially schematic view of one embodiment of the E-field originator of
  • FIGS. 1 and 2 as a terminator.
  • FIG. 11 is a cross-sectional side view of one embodiment of the E-field originator of FIGS. 1 and 2, as a bushing.
  • FIG. 12 is a sectional, partially schematic, side view of one embodiment of the E-field originator of FIGS. 1 and 2, as a shielded bus or shielded cable.
  • FIG. 13 is a sectional, partially schematic, side view of one embodiment of the E-field originator of FIGS. 1 and 2 , as a gas or oil-insulated switchgear
  • FIG. 14 is a sectional, partially schematic, side view of one embodiment of the E-field originator of FIGS. 1 and 2 , as a duct-enclosed bus.
  • FIG 15 is a side view of one embodiment of the E-field originator of FIGS. 1 and 2, as a clamp-on apparatus.
  • FIG. 16 is an alternative embodiment of the electro-optical voltage sensor of FIG. 1 having a current detector.
  • FIG. 1 is a diagram of the electro-optical voltage sensor system
  • a transmitter 1 which is a transmitting means that transmits a beam of electromagnetic radiation (the beam is not shown m FIG 1 but generally designated as 12 elsewhere) and a sensing means, shown in FIG. 1 as a sensor head 4
  • the beam is routed from the transmitter 1 to the sensor head 4 by a polarization maintaining (PM) fiber 18.
  • PM fiber 18 is replaced by low- birefrmgence fiber.
  • Another alternative embodiment whose cost/performance characteristic may be quite different and better suited to certain applications, entails replacement of the PM fiber 18 by single-mode or multi-mode optic fiber.
  • the PM fiber 18 directs the beam from the transmitter 1 into the sensor head 4.
  • Optical signals are routed from the sensor head 4 by a pair of either single-mode or multi-mode optical fibers, shown as 37 and 38.
  • the optical fibers 18, 37, and 38 electrically isolate the sensor head 4 from the transmitter 1 and the rest of the detection system, providing further protection to personnel and equipment from the dangers of high voltage systems
  • the sensor head of the preferred embodiment of FIG. 1 is shown in greater detail in the top-down schematic view of FIG. 8, where the preferred embodiment of the sensor head is generally depicted at 4.
  • the sensor head 4 comprises a polarizer 6, a translucent medium 13, a transducer 5, a retro- reflector generally depicted at 10, a polarizing beam splitter 80 and beam reflector 14.
  • a collimator 26 is connected to the PM fiber 18 and transmits the beam 12 from the PM fiber 18 into the polarizer 6.
  • the polarizer 6 polarizes the beam 12 when the beam 12 is transmitted from the collimator 26; thus, the polarizer 6 polarizes the beam 12 if the beam 12 is not polarized when it is transmitted from the collimator 26, or re-polarizes the beam 12 if the beam
  • the polarizer 6 could be eliminated or placed anywhere between the transducer 5 and the transmitter of the beam 12, including anywhere along the PM fiber 18.
  • the PM fiber 18 can be aligned with sufficient precision with respect to the optical axes of the transducing medium, to perform the function of (and eliminate the need for) the polarizer 6.
  • the beam 12 passes from the polarizer 6 through the translucent medium 13 and into the transducer 5.
  • the translucent medium 13 comprises a non-conductive, non-birefringent material, such as fused quartz or a similar substance, which provides a pathway for the beam from the polarizer 6, which is preferably situated outside the E-field, to the transducer 5, which must reside within the E-field. The source of this E-field will be discussed shortly.
  • the transducer 5 also called the transducing medium
  • the transducer 5 When the transducer 5 (also called the transducing medium) is in a non-zero E-field (not shown) it induces a "differential phase shift" to orthogonal beam components of the beam 12 through the Pockels electro-optic effect, which will now be explained.
  • the polarized beam 12 the light has at least two components which propagate along at least two orthogonal planes, respectively, thus forming at least two orthogonal planes within the beam 12.
  • the phase of the components in each plane of propagation are the object of a shift, relative to the phase of the component in the other plane, in the transducer 5.
  • the Pockels electro-optic effect which takes place in transducer 5, changes the relative phases of the beam components by altering their respective velocities, and is observed in Pockels transducing crystals and similar media.
  • the magnitude of the phase shift is proportional to the magnitude of the E-field.
  • the Pockels electro-optic effect is observed as a "phase differential shift" of the orthogonal beam components which is proportional to the magnitude of the E-field. Due to the fixed coaxial structure of the devices in which the sensor head is to be installed, the magnitude of the E-field is proportional to the voltage. Therefore, the differential phase shift is proportional to (and can be used to measure) the voltage of the E-field between energized conductor and ground conductor.
  • the transducer 5, or transducing medium comprises a material which exhibits the Pockels electro-optical effect.
  • the transducer 5 is preferably Lithium Niobate (LiNb0 3 ) Pockels, although other materials, such as Ammonium Dihydrogen Phosphate (NH 4 H 2 P0 4 ) , Ammonium Dideuteriu Phosphate (NH 4 D 2 PO circumstance) , Potassium Dideuterium Phosphate (KD 2 P0 4 ) , MgO-doped Lithium Niobate (MgO-LiNb0 3 ) , electro-optic polymers, organic materials, and others may be used.
  • the beam may be considered either to be a differential phase shifted signal or an optical polarization modulation signal
  • the polarization modulation signal is used in the present invention because it can be detected using low-cost, components that are less susceptible to temperature, mechanical perturbations, and optical incoherence than those components that would be required to sense the differential phase shift directly.
  • the sensor head 4 or the transducer 5 may be encased m a dielectric buffering material, not shown, to smooth the transition geometry between the permittivity of the transducer 5 and the permittivity of the surrounding media, which m most cases will be an insulator
  • the dielectric buffering material promotes uniformity in the E-field, particularly around the edges of the transducer 5 This enhances uniform phase shift m the beam 12 passing through the transducer 5, and minimizes voltage stress on the materials in and surrounding the sensor head 4 as well, thereby increasing the probable maximum operating lifetime of the entire system.
  • the retro-reflector 10 comprises a reflector material 9 which induces the beam to reflect and causes a quarter-wave retarding of the beam 12.
  • the quarter- wave retarding property of the reflector material 9 induces a 1/4 wavelength shift m the orthogonal planes of the beam 12.
  • the 1/4 wavelength shift can be achieved by reflection of the beam 12 alone, if the material 9 is non-birefnngent , alternatively, the material 9 can comprise birefringent reflector material wherein the properties of the material help achieve the shift.
  • a reflector material 9 having birefringence is used, the phase shifting occurs when orthogonal components of the electromagnetic waves of the beam are shifted (here by 1/4 a wave length) with respect to one another.
  • This birefringence which is inherent m some materials, is not dependant upon the E-field
  • a reflector material 9 which exhibits a reflection-induced retardation to differentially shift the relative phases of the beam components m orthogonal planes m the beam 12 by ⁇ /2 radians.
  • the polarization of the beam 12 incident upon the retro-reflector 10 depends upon the E-field present when the beam 12 makes a first pass through the transducer 5. If there is an E-field present then there will be some differential phase shift already present m the beam 12.
  • the 7r/2 retardation withm the retro-reflector 10 biases the sensor's overall resultant polarization such that zero E-field (and hence zero voltage) corresponds to circular-polarized light, as no differential phase shift is mduced upon the beam 12 by the transducer 5
  • the retro-reflector 10 due to the location of the retro-reflector 10 in the sensor head 4, if the transducer 5 is a non-zero E-field and induces a differential phase shift m the beam 12, then the retro-reflector 10 will not convert light from linear to circular-polarization, rather it will induce elliptical-polarization upon the beam 12, whose ellipticity will vary m proportion to the voltage.
  • the retro- reflector 10 is configured to cause a 180° change m the direction of the beam 12, thereby sending the beam back mto the transducer 5.
  • a beam 12 may be induced to undergo a 1/8 wave length phase shift to produce a total of 1/4 wave phase shift, as m the preferred embodiment.
  • One skilled in the art could further induce a 1/4 wave length shift in beam 12 by combining reflection and birefringence.
  • the beam 12 When the beam 12 reenters the transducer 5, it undergoes further phase shift from the Pockels electro-optic effect. As shown in FIG. 8, the beam 12 then passes through the translucent medium 13 and enters into the polarizing beam splitter 80.
  • the beam 12 is separated accordance with the respective axes of its polarization ellipse into AM signals 35 and 36.
  • the said polarization ellipse will exhibit an ellipticity ranging between -1 and +1, in proportion to voltage at any given time.
  • an elliptic polarization whose ellipticity ranges between -1 and +1 can be described as ranging from a linear polarization along one axis to a linear polarization along a second axis perpendicular to the first axis, wherein the point at which ellipticity equals 0 corresponds to circular polarization. As shown in FIG.
  • the major and minor axes of the polarization ellipse of beam 12 can be represented by two orthogonal components, indicated generally at 83.
  • the beam splitter 80 then separates the beam 12 mto two components 84 and 85 which comprise the intensities along each of the two axes of the polarization ellipse shown as orthogonal components
  • the intensity of beam components 84 and 85 will modulate conversely to one another in response to modulations in the ellipticity of the beam's polarization.
  • the beam components 84 and 85 are two AM signals shown as 35 and 36, respectively, which are routed as shown in FIG. 1 into photo-detectors 43 and 44, respectively.
  • the AM signals 35 and 36 are then passed by colli ators 27 and 28, shown in FIG. 8, and routed through multi-mode or single-mode optic fibers 37, 38.
  • a beam reflector 14 may be used to aid in routing the AM signals 35 and 36.
  • first and second routing means shown as optic fibers 37 and 38, are used to route the AM signals 35 and 36 from the sensing means into the detecting means.
  • First the AM signals 35 and 36 are routed into the photodetectors 43 and 44 through the first and second routing means, shown as the first and second translucent fibers 37 and 38, respectively.
  • the first and second translucent fibers 37 and 38 comprise at least one optic fiber, wherein the optic fiber is selected from the group consisting of : a single-mode optic fiber, and a multi-mode optic fiber.
  • the AM signals 35 and 36 become electrical signals 45 and 46.
  • the electrical signals 45 and 46 are routed into a signal processor
  • the final component of the detecting means wherein a desired E-field characteristic is determined, particularly that of voltage.
  • the signal processor 62 is designed to sample each AM signal at substantially regular intervals and substantially simultaneous times, process the signals to produce a display signal (not shown) which is then displayed on a readable display such as: digital, hardcopy, video, software, computer memory displays or an audible indicator. While it is possible to actually measure the relative phases of the orthogonal components of the beam 12 after exiting the transducer, the relative phase shift can also be derived from the intensities of the AM signals 35 and 36 shown in FIG. 8 without using complex and costly approaches as involved in direct phase measurements.
  • the beam's polarization state is analyzed to obtain AM intensity signals.
  • the AM signals 35 and 36 extracted from the beam's polarization state by the splitter 80 are transmitted to and used in the signal processor 62 where their complementary nature facilitates rejection of common mode noise and minimizes effects of temperature dependent intrinsic birefringence that may reside in the transducing medium or other optical components within the system.
  • This feature of the present invention substantially enhances accuracy and practicality of the system and represents an additional advancement over much of the prior art .
  • the signal processor 62 performs these functions while converting the received AM signals 35 and 36 into a single, highly accurate voltage measurement .
  • the invention may be used in conjunction with a device for measuring current to provide information regarding power, power factor angle, and energy on the conductor of interest.
  • each AM signal, 35 and 36 is converted by a photo-detector 43 and 44 (FIG. 1) into a electrical signal 45 and 46 (FIG. 1) which can be processed by the signal processor 62.
  • the photo- detector comprises an optic-to-electronic conversion means for converting said AM signals into analog electronic signals.
  • the analog electronic signals comprise low-level analog voltage signals or current signals .
  • the electrical signals 45 and 46 are electronic signals transmitted to the signal processor
  • each of the electrical signals 45 and 46 corresponds to intensity of eacn AM signal 35 and 36.
  • the electrical signals 45 and 46 are sampled by the signal processor 62 at regular intervals and substantially simultaneously with one another.
  • the sampled signals are the instantaneous intensity for each AM signal, 35 and 36.
  • the instantaneous intensity signal for each beam component is sampled sequentially and stored, thereby forming a data base of stored signals which represents each AM signal over time
  • the stored signals are then converted into a displayable signal regarding the voltage of E-field at the transducer 5 (FIG 8)
  • signals are manipulated the following manner.
  • an average intensity for each independent amplitude modulated signal is calculated. This is done by summing the instantaneous intensities of the signals which have been sampled over a pre-determined time interval and dividing by the number of samples taken m the mterval. In the preferred invention this is accomplished by taking the average of the signals over time for each beam component by summing the signals of each beam component and dividing the sum by the number of signal samples taken
  • the average intensity for the AM signal (A) is expressed as follows:
  • the average intensity is (A)
  • the instantaneous AM signal is (A )
  • the number of samples is (L)
  • the samples are taken and stored at uniform time intervals d)
  • the average is calculated usmg samples between present time index n and past time index (n- L)
  • the average intensity for the AM signal (B) is expressed as follows-
  • the average intensity is (I)
  • the instantaneous AM signal is (BJ , with the other values being as above.
  • the adjusted instantaneous intensity (I n ) is:
  • (B n ) is the instantaneous intensity of signal (B) at the present time
  • signals (A) and (B) each represents a different axis on the polarization ellipse, their amplitudes will change in opposite directions from one another for a given change m polarization.
  • the adjusted instantaneous intensity signals (I n ) and (J n ) must be computed as indicated above in order to preserve sign.
  • the adjusted average instantaneous intensity signal for both signals (A) and (B) compensates for any temperature induced birefringence that may exist within the transducer. Temperature mduced birefringence causes a change m the intensity of the
  • the scaling constant (k) is determined by applymg a precisely known voltage to the device of interest and adjusting the scaling constant (k) until the value measured as the actual instantaneous voltage
  • V n is equivalent to the precisely known voltage being applied.
  • the sensor head 4 is placed in an insulator 50 between a conductor 52 and a grounded conductor 48.
  • an E-field is created between the conductor 52 and the grounded conductor 48, m the insulator 50.
  • Determination of the scaling constant (k) is accomplished by applying a precisely known voltage to the conductor 52. Once the scaling constant (k) is known the electro-optical voltage sensor system may be operated to determine additional actual instantaneous voltages applied to conductor 52.
  • FIG. 2 is a diagram of the electro-optical voltage sensor system.
  • a transmitter 1 which comprises a laser (not shown) , a polarizer 6, and a wave plate 9.
  • the laser emits an electromagnetic radiation beam 12.
  • the electromagnetic radiation beam 12 passes first through a polarizer 6 and then a wave plate 9, producing a polarized beam 12 which may be circular- polarized.
  • the beam 12 enters mto a PM optic fiber 18 through a collimator 20.
  • the PM optic fiber 18 may further comprise a low-birefrmgence optic fiber
  • the optic fiber 18 routes the beam 12 to a sensor head generally designated at 16 It is important to note that the sensor head 16 m this alternative embodiment shown m FIG. 2 differs from the sensor head 4 of the preferred embodiment shown m FIG. 1.
  • the detector generally depicted at 8, as shown m FIG. 2, comprises a polarizing beam splitter 80, at least two photo-detectors 43, 44, a signal processor 62.
  • the beam 12 is routed from the sensor head 16 through another PM optic fiber 19 through a collimator
  • the polarizing beam splitter 80 separates the polarized beam 12 m accordance with the respective separate wave components propagating the orthogonal axes of the polarization ellipse mto AM signals 35, 36.
  • the AM signals 35, 36 which are analog optic signals, are routed through multi-mode or smgle-mode optic fibers 37, 38 to the photo-detectors 43, 44.
  • the photo-detectors convert the AM signals 35, 36 into electrical signals 45, 46 which can be analyzed m the signal processor 62.
  • a collimator 29 comprises a lens 30 and a transparent end 31 which can pass a beam 12 mto or out of the core 32 of an optic fiber 40.
  • a collimator used to couple light mto the core of an optic fiber is sometimes also referred to as a "coupler” m the art, but the term “collimator” is used herein for simplicity.
  • the optic fiber 40 is a PM optic fiber 18, which may also take the form of low-birefringence fiber. Referring to FIGS.
  • these alternative embodiments of the sensor head 16 comprise a transducer 5 and a reflector 17.
  • the beam 12 enters into the sensor head 16, through a collimator 21 which is attached to a PM fiber 18.
  • the beam 12 then passes through the transducer 5 and upon being reflected by a beam reflector 17 enters into a second collimator 22.
  • the second collimator 22 is connected to an optical fiber 19 by which the beam 12 is routed away from the sensor head 16.
  • the beam only passes through the transducer once .
  • the beam 12 enters into the sensor head 16, through a collimator 21 which is attached to a PM fiber 18, following which it is reflected by the beam reflector 17 into the transducer 5.
  • the beam 12, after passing through the transducer 5 would enter into a second collimator 22 connected to an optical fiber 19 and be routed away from the sensor head 16.
  • the beam 12 enters into the sensor head 16, following which it travels through the transducer 5.
  • the beam 12 is then reflected by the beam reflector 17 back through the transducer 5, and into a second collimator 22 connected to an optical fiber 19.
  • the beam 12 is then routed away from the sensor head 16.
  • the sensor heads 4 and 16 each have a cross-sectional area of only approximately fifty millimeters squared (50 mm 2 ) or less, and a length of approximately twenty five centimeters (25 cm) or less, depending upon the particular apparatus in which the sensor head is embedded.
  • the transducer 5 There are two alternative embodiments of the transducer 5 which vary according to intrinsic birefringence.
  • the first embodiment of the transducer 5, as shown in FIG. 5, is particularly appropriate where the transducer material 5 does not exhibit intrinsic birefringence along the propagation axis, shown as z.
  • the beam 12 propagates along axis z.
  • the transducer 5 in the presence of the E-field 90 causes differential phase modulation in the orthogonal planes of the beam 12.
  • the embodiment shown in FIG. 5 is preferred where the transducer 5 exhibits no intrinsic birefringence. It is desirable to avoid intrinsic birefringence, as it is typically temperature dependant .
  • the second embodiment for the transducer 5 which exhibits intrinsic birefringence is shown in FIG 6.
  • the transducer 5 and a second transducer 11 have matched intrinsic birefringence to one another along the propagation axes, shown as y' .
  • the transducer 5 is aligned with the second transducer 11 such that the optic axes y' are rotated ninety degrees (180°) with respect to one another.
  • the E-field 90 aligned along the z axes, achieves a reverse polarity in the second transducer 11.
  • the orientation of the beam 12 with respect to the optic axes y' is preserved by the rotation of the beam 12 by ninety degrees (90°) .
  • This rotation of the orientation is achieved by placement of a 90° polarization rotator 7 between the first transducer 5 and the second transducer 11. This configuration achieves cancellation of the effects of intrinsic temperature dependant birefringence, while yielding a differential phase shift in each transducer
  • the beam 12 goes through the transducer 5 to the 90° polarization rotator 7, and thence through the second transducer 11.
  • a shielded joint 100 is used to connect shielded conductors 52 to one another, and may take the form of either a splice or pre-molded connector.
  • the two conductors 52 connected to one another are each enclosed within insulation 50, around which is a semi-conducting jacket 109 and a cable ground shield 111.
  • Around the conductor connecting means 104 is a layer of shielded joint insulation 108 and a joint ground shield 102.
  • the joint ground shield 102 is supported in place by the end caps 115.
  • a ground shield connector 113 can be used to maintain a common ground potential upon the cable ground shields 111 and the joint ground shield 102.
  • the cable ground shields 111 are electrically connected by conductive wire 106 attached to ground shield connector 113.
  • the cable ground shields 111 can be physically connected to the joint ground shield 102 at the intersection points without use of a ground shield connector 113 or conductive wire 106.
  • the sensor head 4 is disposed between the joint ground shield 102 and the conductor connecting means 104.
  • the optical fibers 18, 37, 38 route the beam to and from the sensor head 4.
  • FIG. 10 Another expression of the E-field originator 96 is the terminator 118 shown in FIG. 10.
  • a conductor 52 is enclosed within insulation 50 forming a transition span.
  • the insulation 50 is enclosed within a voltage gradient control means 120.
  • a cable ground shield 111 may partially enclose the voltage gradient control means 120.
  • the sensor head 4 is disposed between the conductor 52 and the voltage gradient control means 120.
  • Optical fibers 18, 37, 38 route the beam to and from the sensor head 4.
  • the E- field of interest, and into which the sensor head 4 is introduced, arises between conductor 52 and the voltage gradient control means 120 when a voltage is present upon the conductor 52.
  • FIG. 11 Another expression of the E-field originator 96 of FIGS. 1 and 2 is the through-hole insulator 124, here shown as a transformer bushing in FIG. 11.
  • a conductor 52 is enclosed within insulation 50, which is enclosed within a grounded conductor 48.
  • the through-hole insulator shown here as a transformer bushing has a mounting flange 126 for mounting the bushing and creepage distance skirts 128 which extend from the grounded conductor 48.
  • the sensor head 4 is disposed between the conductor 52 and the grounded conductor 48.
  • Optical fibers 18, 37, 38 route the beam to and from the sensor head 4.
  • the E- field of interest, and into which the sensor head 4 is introduced arises between the conductor 52 and the grounded conductor 48 when a voltage is present upon the conductor 52.
  • FIG. 12 Another expression of the E-field originator 96 of FIGS. 1 and 2 is the shielded cable or bus 129, shown in FIG. 12.
  • a conductor 52 is enclosed within insulation 50, which is enclosed within a grounded conductor 48.
  • the sensor head 4 is disposed between the conductor 52 and the grounded conductor 48.
  • Optical fibers 18, 37, 38 route the beam to and from the sensor head 4.
  • the E-field of interest, and into which the sensor head 4 is introduced, arises between the conductor 52 and the grounded conductor 48 when a voltage is present upon the conductor 52.
  • FIG. 12 shows a bus having a round cross- section
  • an alternative and equivalent embodiment comprises a rectangular (or square) cross-section.
  • FIGS. 1 and 2 Another expression of the E-field originator 96 shown in FIGS. 1 and 2 is the gas or oil-insulated switchgear 132, shown in FIG. 13.
  • a conductor 52 is enclosed within gas or oil insulation 134, by a grounded conductive or se i- conductive containment means 140 for containing the gas or oil insulation.
  • the sensor head 4 is disposed between the conductor 52 and the grounded containment means 140.
  • Optical fibers 18, 37, 38 route the beam to and from the sensor head 4.
  • the E-field of interest, and into which the sensor head 4 is introduced, arises between the conductor 52 and the grounded containment means 140 when a voltage is present upon the conductor 52.
  • FIG. 14 Another expression of the E-field originator 96 is the duct-enclosed bus 142, shown in FIG. 14.
  • a conductor 52 is enclosed within insulation 50 of sufficient thickness to minimize possibility of flash- over.
  • the insulated bus is enclosed within a grounded duct or other grounded at least semi-conducting means 144.
  • at least semi-conducting it is meant all semi-conducting and conducting means, by which the bus can be grounded.
  • the sensor head 4 is disposed between the conductor 52 and the grounded semi ⁇ conducting means 144.
  • Optical fibers 18, 37, 38 route the beam to and from the sensor head 4.
  • the E-field of interest, and into which the sensor head 4 is introduced arises between the conductor 52 and the grounded semi-conducting means 144 when a voltage is present upon the conductor 52.
  • the clamp-on apparatus 147 Another expression of the E-field originator 96 is the clamp-on apparatus 147, shown in FIG. 15.
  • a conductor 52 is enclosed within a coaxial conductive grounded surrounding means 149.
  • the conductor 52 is preferably a nonshielded transmission line, a nonshielded cable, or a nonshielded bus.
  • the conductor 52 is separated from the conductive grounded surrounding means 149 by insulated standoff means 151.
  • the sensor head 4 is disposed between the conductor 52 and the coaxial conductive grounded surrounding means 149.
  • Optical fibers 18, 37, 38 route the beam to and from the sensor head 4.
  • the E-field of interest, and into which the sensor head 4 is introduced arises between the conductor 52 and the coaxial conductive grounded surrounding means 149 when a voltage is present upon the conductor 52.
  • FIG. 16 is an alternative embodiment of the electro-optical voltage sensor of FIG. 1, having a current detector 153 disposed substantially in common with the sensor head.
  • the current detector 153 detects the current, not shown, passing through the conductor 52 by detecting the magnetic field, not shown, associated with the current.
  • the current detector provides a current signal, not shown, which is routed through a current signal routing member 156 to the signal processor 62.
  • the optical current signal routing member 156 consists of optic fiber, photodetection means, and electrical connecting means, none of which are shown.
  • a combination of at least two sensors of the present invention may be used to achieve a line-to- ground voltage measurement on separate conductors of a multi-source system.
  • Multi-source system is meant a to include both a multi-phase as well as a multi-line system.
  • line-to-ground measurements may also be used to calculate line-to-line voltages through simple subtraction of line-to-ground values.
  • the present invention represents a significant advance over the prior apparatus, methods and art of voltage measurement .
  • the present invention does not require any additional electronics to bias the transducing material to determine voltage, such as a voltage divider.
  • Voltage is determined in the present invention by utilizing the E-field that exists within many types of devices to transmit and distribute power, often these power distribution devices are co- axial, which simplifies the application of the present invention.
  • the E-field which is proportional to voltage, is used to bias a transducing element in order to induce a differential phase shift in the orthogonal planes of the beam, which as modulated optic signals, is proportional to voltage.
  • the sensor head of the present invention which may be installed or built mto the described voltage transmission and distribution apparatus, voltage measurement is achieved without the use of a large, dedicated, stand-alone voltage division device. Real estate withm Power substations s at a premium, thus this sensor system offers a substantial economic advantage due to space savings.
  • contact with the energized conductor is substantially reduced and in most cases altogether eliminated with the practice of the present invention This is advantageous, as an energized conductor can present significant life and health risks among other hazards where high voltages are involved Further, the practice of the present invention does not interfere with the apparatus being measured, and avoids various other problems associated with the use of the voltage dividers in the prior art

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  • Physics & Mathematics (AREA)
  • General Physics & Mathematics (AREA)
  • Measuring Instrument Details And Bridges, And Automatic Balancing Devices (AREA)
  • Measurement Of Current Or Voltage (AREA)

Abstract

L'invention concerne un voltmètre électro-optique permettant de mesurer des tensions sans erreurs notables imputables aux conducteurs voisins ou aux perturbations de proximité. Le voltmètre comporte un émetteur (1), un capteur (4), un détecteur (43, 44) et un module de traitement (62) du signal. L'émetteur produit un faisceau de rayonnement électromagnétique qui est dirigé vers le capteur. Dans le capteur (4), le faisceau subit l'effet électro-optique de Pockels. L'effet électro-optique produit une modulation de la polarisation du faisceau qui, à son tour, est convertie en uen paire de signaux indépendants à modulation réciproque d'amplitude, à partir desquels le module (62) de traitement du signal est capabe de déterminer la tension du champ électrique. Le recours à des signaux de modulation réciproque d'amplitude permet au module (62) de traitement du signal de faire une meilleure discrimination entre le signal et le bruit. Pour convertir le faisceau, le capteur (4) décompose, en au moins deux signaux en modulation d'amplitude, le faisceau selon les axes de l'état de polarisation du faisceau (une ellipse dont l'ellipticité varie entre -1 et +1 en proportion de la tension). Ces signaux sont fournis au module de traitement (62) du signal et traités de façon à déterminer la tension entre le conducteur de terre et le conducteur (2) sur lequel on mesure la tension.
PCT/US1996/019346 1995-12-08 1996-12-05 Voltmetre electro-optique Ceased WO1997022012A1 (fr)

Priority Applications (4)

Application Number Priority Date Filing Date Title
CA002239722A CA2239722C (fr) 1995-12-08 1996-12-05 Voltmetre electro-optique
EP96944754A EP0866975A4 (fr) 1995-12-08 1996-12-05 Voltmetre electro-optique
JP52210397A JP2001526770A (ja) 1995-12-08 1996-12-05 電気光学電圧センサ
AU13291/97A AU1329197A (en) 1995-12-08 1996-12-05 Electro-optic voltage sensor

Applications Claiming Priority (4)

Application Number Priority Date Filing Date Title
US08/569,338 1995-12-08
US08/569,338 US5892357A (en) 1995-12-08 1995-12-08 Electro-optic voltage sensor for sensing voltage in an E-field
US08/570,152 US5731579A (en) 1995-12-11 1995-12-11 Electro-optical voltage sensor head
US08/570,152 1995-12-11

Publications (1)

Publication Number Publication Date
WO1997022012A1 true WO1997022012A1 (fr) 1997-06-19

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EP (1) EP0866975A4 (fr)
JP (1) JP2001526770A (fr)
AU (1) AU1329197A (fr)
CA (1) CA2239722C (fr)
MY (1) MY125659A (fr)
WO (1) WO1997022012A1 (fr)

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CN109709408A (zh) * 2019-03-08 2019-05-03 广东省职业病防治院 空间直流电场测量设备
CN113917242A (zh) * 2021-09-28 2022-01-11 华中科技大学 一种导体电晕放电电场非介入测量系统及其应用
US11500034B2 (en) * 2019-10-18 2022-11-15 Prysmian S.P.A. Electrical cable structure analysis method and apparatus

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JP5534653B2 (ja) * 2008-05-28 2014-07-02 株式会社東芝 光電圧センサ

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US4147979A (en) * 1975-04-16 1979-04-03 Siemens Aktiengesellschaft Movable probe carrying optical waveguides with electro-optic or magneto-optic material for measuring electric or magnetic fields
US4412173A (en) * 1981-01-26 1983-10-25 The Oregon Graduate Center For Study And Research Apparatus using leakage current for measuring resistivity
US4510441A (en) * 1981-06-12 1985-04-09 Kabushiki Kaishi Meidensha Electric field detector
US5113331A (en) * 1991-08-09 1992-05-12 General Motors Corporation Vehicle headlamp assembly

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Cited By (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN109709408A (zh) * 2019-03-08 2019-05-03 广东省职业病防治院 空间直流电场测量设备
CN109709408B (zh) * 2019-03-08 2024-05-10 广东省职业病防治院 空间直流电场测量设备
US11500034B2 (en) * 2019-10-18 2022-11-15 Prysmian S.P.A. Electrical cable structure analysis method and apparatus
CN113917242A (zh) * 2021-09-28 2022-01-11 华中科技大学 一种导体电晕放电电场非介入测量系统及其应用

Also Published As

Publication number Publication date
AU1329197A (en) 1997-07-03
CA2239722A1 (fr) 1997-06-19
MY125659A (en) 2006-08-30
EP0866975A4 (fr) 1998-12-23
CA2239722C (fr) 2003-04-29
EP0866975A1 (fr) 1998-09-30
JP2001526770A (ja) 2001-12-18

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