Guidance and Control Division

Flight computers and sequencers, spacecraft power and control systems, and guidance and control analysis and integratio

Analysis of high voltage impulse generator circuits

A study is made of transient or oscillatory voltages which arise in an impulse generator of the two-column Marx type during the firing process (i.e. between the breakdown of the first and the last spark-gap and immediately thereafter). These voltages are liable to appear on the external test and measuring equipment, but this aspect is not dealt with, nor are the spark-gap characteristics investigated systematically. The voltages are shown to be relatively independent of the main circuit elements, but to be set up in the stray capacitative and inductive fields in the generator, structure. These fields are resolved into an equivalent circuit involving measurable parameters. A matrix method is developed to analyze its dynamic properties, the solution being given in terms of eigenvalues. It is particularly suited to numerical treatment on a digital computer. The theory is extended, tentatively, to the evaluation of optimum damping resistances. By a second approach, the generator is represented by a one-dimensional lattice circuit. Although an explicit solution is not obtained, some propagation characteristics are determined, enabling comparison to be made with the one-column type of generator (and with such analogous problems as transformer windings). The gaps cannot in general be assumed to fire simultaneously. The transient voltages are of primary importance in causing their successive breakdown, but the instant of breakdown due to an overvoltage cannot be determined from present data. Again, the firing of the gaps constitutes the excitation to the circuit, but it is doubtful whether they behave as ideal switches. These two factors make a complete solution impracticable. The experimental work made use of a four-stage generator. Voltages calculated from measured parameters are compared with oscillographic measurements. Sources of error in the capacitance-divider circuit are investigated and compensation for the connecting leads shown to be desirable

ANALYSIS OF THE TRANSIENT STABILITY LIMIT OF NIGERIA’S 330kV TRANSMISSION SUB-NETWORK

The poor investment in the network expansion programme has led to high level of grid fragility experienced in the power transmission system in Nigeria. Thus, any little disturbance often results in cascaded outage which is very hazardous to the power system equipment and operation. In order to overcome or ameliorate the influence of this challenge, the network engineers have to devise methodologies based on the dynamic stability analysis. This motivates the development of power system transient stability model presented herein. The developed model is thus applied to a specimen of the Nigeria’s transmission power system, i.e. the Ikeja-West Sub-network. This choice is influenced by the fact that the Ikeja-West sub-network is the hub of power transmission arteries in Nigeria. Thus the Electrical Transient and Analysis Program (ETAP) software is deployed to operate on the ensuing model. This then leads to generating a series of results that demonstrates the different scenarios in respect of the system stability studies. The method adopted is quite appealing and promising as a tool in sustaining system stability and security during slight disturbance to the network during operation.http://dx.doi.org/10.4314/njt.v36i1.2

Experimental Investigation of Self-excitation on 60-cycle, Single-phase Fower Circuits

Engineerin

Optical studies of the pre-breakdown mechanism in dielectronic liquids.

PhDThe work described in this thesis provides an optical study of pre-breakdown events in liquid dielectrics. A small scale rig employing a 50SI test cell with viewing windows, as part of a high voltage co-axial line, enabled short rise time pulses to be applied to a non-uniform test gap. For the liquid dielectric, changes of refractive index resulting from applied voltage were rendered visible by means of a Schlieren optical system. A high speed image converter camera enabled rapidly changing pre-breakdown phenomena to be photographically recorded at framing speeds up to 107 per second. Scattered light photographs were taken by orthogonal flash illumination under both pulse and direct voltage conditions, allowing large format macrophotography. Using a piezoelectric transducer placed within the test cell, and a photomultiplier to view the gap region, a relationship has also been established between the generation of mechanical waves, light scintillation and conduction current pulses. From the photographic records and conventional parameter measurements there exists strong evidence for the presence of a gaseous phase in processes leading to the electrical breakdown of liquid dielectrics even under pulse conditions

A Computer-Automated Laboratory System In A University Environment

A computer-automated laboratory system at the University of Missouri-Rolla, Rolla, which serves a wide variety of instruction and research disciplines including Geophysics, Cloud Physics, and Computer Graphics, is described. The system serves as an example for campuses which are relatively small in geographic area and with budget limitations which dictate a step-by-step evolution. The paper describes 1) the constraints and economics realized in the development of the system, 2) the characteristics of the minicomputer network, and 3) an evaluation of the system philosophy and performance. Also included is a description of diverse laboratory projects supported by the computer-automated system. © 1975, IEEE. All rights reserved

Measurement of radio frequency noise in urban, suburban, and rural areas Final report

Measurements of urban, suburban, and rural radio frequency noise interfering with aircraft communicatio

The electrical diagnosis of peripheral nerve injury, and some applications of electronics to physiology and clinical medicine

In the summer of 1941 the Scottish E. M. S. Hospitals organization established a special Unit for the reception and treatment of patients suffering from peripheral nerve injury at Gogarburn Hospital on the outskirts of Edinburgh. In connection with this specialized type of injury, relatively rare in peacetime but assuming considerable importance in War, invitations were issued to various Persons sroecializing in ancillary branches of Medicine and Surgery to attend the clinical meetings of the Peripheral Nerve Unit, to consider applications of their work to this particular problem, and to have access to the patient for the assessment of their methods.Peripheral nerve injury diagnosis and treatment involves a considerable field of application for methods which have been primarily developed as physiological techniques, particularly in the use of modern electrical apparatus, and the Director of the Unit, Professor J. R. Learmonth, invited me to attend the clinical meetings, and to make a study on the patients of modern methods of electrical diagnosis, and this opportunity, gladly accepted, has furnished me with a wealth of problems and of material ever since.This thesis accordingly presents such of these problems as have at present been worked out to the extent of being of clinical or laboratory use

Operation and maintenance manual for universal pfm real-time data-reduction system

Operation and maintenance manual for universal pulse frequency modulation /pfm/ real time data reduction syste