Power system applications of fiber optics

Power system applications of optical systems, primarily using fiber optics, are reviewed. The first section reviews fibers as components of communication systems. The second section deals with fiber sensors for power systems, reviewing the many ways light sources and fibers can be combined to make measurements. Methods of measuring electric field gradient are discussed. Optical data processing is the subject of the third section, which begins by reviewing some widely different examples and concludes by outlining some potential applications in power systems: fault location in transformers, optical switching for light fired thyristors and fault detection based on the inherent symmetry of most power apparatus. The fourth and final section is concerned with using optical fibers to transmit power to electric equipment in a high voltage situation, potentially replacing expensive high voltage low power transformers. JPL has designed small photodiodes specifically for this purpose, and fabricated and tested several samples. This work is described

Electrooptic electric field sensor for dc and extra-low-frequency measurement

This thesis was submitted for the degree of Doctor of Philosophy and awarded by Brunel University.The thesis reports the results of the research carried out towards the development of an electrooptic sensor for DC and extra low frequency electric field measurement. Available cubic electrooptic crystals were compared from the sensor sensitivity point of view. A new figure of merit was used taking into account the attenuation of the electric field in the dielectric crystal and its shape. The effect of optical activity in 23 cubic crystals was analyzed using the concept of Poincare sphere. The cubic crystals were further characterised for the charge relaxation time constant to estimate their performance in DC field measurements. Crystals of Bismuth Germanate and Lithium Niobate were identified as suitable materials for the DC field sensor. The selected crystals were found suitable at extra-low-frequencies. DC field measurements, without the rotation of the crystal, were possible only with Lithium Niobate. However, its performance was influenced to a great extent by the effect of stimulated conductivity. The quarter-wave plate and the crystal of Lithium Niobate were identified as the main sources of temperature instability. A new method of temperature compensation of the quarter-wave plate is proposed. Due to the temperature instability of Lithium Niobate, mainly attributed to the pyroelectric effect and natural birefringence, it is difficult to use the sensor in practical applications. The performance of the sensor is significantly affected by the presence of an external space charge. The proposed method of its elimination using an artificial extension of the sensing element did not reduce the space charge effect adequately. The response of the sensor in a space charge environment was found to be linear and independent of the space charge density. This enabled measurements of static fields in a unipolar environment. The direct field measurements in bipolar environment suffered from a drift which is intolerable in practical measurements. The minimum detectable electric field of this sensor in the frequency range from 1 to 200Hz was 1V/m, with a signal to noise ratio equal to 0dB and a resolution of 1V/m. The static field measurements were limited to measurements of pulses with a duration of 200s, due to a long term drift of photodetectors. The minimum detectable level of DC electric field was 2.4kV/m.EPSR

Sensing and interferometry, including design and characterisation of special optical fibres

This thesis presents my work in the area of optical fibre sensing, and optical fibre design and characterisation along with the interferometric and signal processing techniques that were developed along the way

Sensing and interferometry, including design and characterisation of special optical fibres

This thesis presents my work in the area of optical fibre sensing, and optical fibre design and characterisation along with the interferometric and signal processing techniques that were developed along the way

Proof of principle non-invasive pulsed electric field study (measurement and experiments)

Pulsed electric field (PEF) technology applied to food processing was firstly used in the late 1960s. The currently available systems use either conventional Blumlein generators or generators similar to those found in radar power sources to produce the required high voltage pulses. The liquid to be processed is passed through a number of treatment chambers or cells which each contain a pair of electrodes in contact with the liquid. An electric field is thereby applied to the liquid, leading to the technology being termed invasive and it can be used only with liquid food. A novel and non-invasive PEF technology for use in the food processing industry is introduced and investigated in this thesis. The technology represents a novel way of performing PEF treatment. A proof of concept arrangement uses two ceramic cylinders mounted inside the non-invasive PEF cell with a gap of 3 mm between them. A displacement current of the order of mA passes through the non-invasive PEF cell during treatment, as compared with the kA of current usually produced during an invasive treatment. The low current is not only economic in electric energy but also maintains a low food temperature, which implicitly maintains food flavour. In the thesis the electro-optic Kerr effect technique is used to perform accurately the PEF measurement and convincingly prove that strong electric fields are present. Two Kerr water cells were designed and used to determine the Kerr constant for water, since the data presented in the literature is unreliable. The first Kerr water cell uses a pair of Bruce profile stainless steel electrodes and the second a pair of parallel plate stainless steel electrodes. An electro-static solver (Maxwell software) was used to determine the electric field distribution and to calculate the electric field integral to accurately determine the Kerr constant for water. Water samples containing the E-coli bacteria were prepared and filled in the non-invasive PEF cell by the Flavometrix Company. Eight PEF experiments were successfully performed during this research programme and the results show unequivocally that the novel noninvasive technique is effective in significantly reducing the initial concentration of E-coli bacteria. This opens the door for the future design of an industrial prototyp

The NASA SBIR product catalog

The purpose of this catalog is to assist small business firms in making the community aware of products emerging from their efforts in the Small Business Innovation Research (SBIR) program. It contains descriptions of some products that have advanced into Phase 3 and others that are identified as prospective products. Both lists of products in this catalog are based on information supplied by NASA SBIR contractors in responding to an invitation to be represented in this document. Generally, all products suggested by the small firms were included in order to meet the goals of information exchange for SBIR results. Of the 444 SBIR contractors NASA queried, 137 provided information on 219 products. The catalog presents the product information in the technology areas listed in the table of contents. Within each area, the products are listed in alphabetical order by product name and are given identifying numbers. Also included is an alphabetical listing of the companies that have products described. This listing cross-references the product list and provides information on the business activity of each firm. In addition, there are three indexes: one a list of firms by states, one that lists the products according to NASA Centers that managed the SBIR projects, and one that lists the products by the relevant Technical Topics utilized in NASA's annual program solicitation under which each SBIR project was selected