摘要:

The paper outlines the development of instruments for measuring and recording wind speed and direction by various electrical means. Methods of calibration and standardization are discussed in relation to the accuracy and speed of response of standard instruments, and some further models which were made for special investigations, or which are still in the development stage, are described. For general use in the Meteorological Office, the most suitable combination of instruments is a cup anemometer of the generator type with an autographic recorder consisting of some form of recording voltmeter and a remote-recording wind vane connected by a self-synchronous a.c. transmission system to a recorder which is capable of being operated by a small torque. The cup anemometer will record the speed of the wind and the wind vane will record its direction.

DOI:10.1049/pi-2.1951.0123

出版商:IEE    

年代:1951

数据来源: IET

摘要:

A description is given of two recorders and an anemometer for measuring gusts, which were developed for use in a survey of the available wind-power in Great Britain. The essential feature of the recorders is that they operate unattended for a period of one week. The first instrument is a photographic recorder which shows, at intervals of half an hour, the wind direction and the run of wind past four standard cup contact anemometers. The second instrument records a mark for each two miles of wind, and will make up to four simultaneous records. The anemometer for measuring gusts uses a perforated aluminium sphere as the detecting element and a mechanoelectronic transducer valve to convert the mechanical response to an electrical output. It is compensated for changes of temperature and for the static effects of atmospheric pressure. When used with an amplifier-driven recording voltmeter, the response of the prototype instrument to an instantaneous change of wind speed from 65 to 85 m.p.h., was completed in about 0.07 sec. Modified forms of the instrument are described which measure, respectively, the horizontal components of the wind in two directions at right angles and the vertical component.

DOI:10.1049/pi-2.1951.0124

出版商:IEE    

年代:1951

数据来源: IET

摘要:

The paper describes two instruments made for use on naval craft during the 1939–45 War. The first was fitted to auxiliary aircraft carriers, and indicated the mean wind direction, so that the vessel might be steered correctly for the take-off and landing of aircraft. The second instrument was fitted on larger naval craft, for meteorological purposes. Its function was to indicate, in various positions in the ship, the direction and speed of both the mean true and the mean apparent winds.The components used in both instruments are magslip transmission elements and electrical computing devices, which were developed for fire-control purposes and subsequently adopted for the meteorological applications.

DOI:10.1049/pi-2.1951.0125

出版商:IEE    

年代:1951

数据来源: IET

摘要:

A knowledge of the behaviour of the true wind aboard ship is essential in modern meteorological practices. The true wind velocity can be resolved from the measured speed and direction of the relative wind and of the ship. A method of polar resolution by alternating current representation of force vectors is shown, together with an outline of the apparatus needed for primary measurement and resolution. The accuracy of the original resolving gear under practical conditions is indicated.

DOI:10.1049/pi-2.1951.0126

出版商:IEE    

年代:1951

数据来源: IET

摘要:

The paper describes a new system of meteorological sounding employing secondary-radar principles. Pressure, temperature and humidity are each telemetered to an accuracy of one-thousandth part of their operating range, although the elements at present used may not be capable of measuring the meteorological parameters to this degree of accuracy. In addition, wind speed and direction are automatically measured. The maximum slant range of the system is about 100 miles, and thus the height to which soundings and wind measurements can be made is, at present, largely limited by the height at which the balloon carrying the instruments bursts.

DOI:10.1049/pi-2.1951.0129

出版商:IEE    

年代:1951

数据来源: IET

摘要:

The manually operated frost-point hygrometer and a frost-point hygrometer employing photo-electric indication of the dew or hoar-frost deposit, have both shown their value as meteorological instruments; both can measure absolute humidities as low as 1 mg/m3, corresponding to a frost point of −80°C. To reduce the observational skill required, a fully automatic hygrometer was developed; the conditions which the automatic instrument must fulfil are outlined and some of the special difficulties are discussed. A brief description is given of an instrument which has fulfilled laboratory tests and will measure any frost point from room temperature down to −80°C. Operation below about −80°C is impossible, owing to the slow rate of crystal growth at such temperatures.

DOI:10.1049/pi-2.1951.0130

出版商:IEE    

年代:1951

数据来源: IET

摘要:

The paper describes four electrically operated meteorological instruments, traces the reasons for their development and gives some examples of the uses to which they are put. The first instrument—a wind-run analyser—records the run of wind over successive time intervals which may be varied from five minutes to one hour. The wind-direction recorder shows, on meters, the run of wind over any desired period, from each of eight directions. The third instrument, an equivalent-air-temperature recorder, measures the equivalent temperature to which walls of various orientations are exposed, taking into account air temperature, radiation and air movement. Finally, the paper describes a temperature integrating and averaging device, from which the mean temperatures of the preceding period may be read directly.

DOI:10.1049/pi-2.1951.0131

出版商:IEE    

年代:1951

数据来源: IET

摘要:

The Earth's magnetic field has the properties of direction and intensity. In navigation, the direction of the horizontal component of this field is required to be known. The customary method is to use a pivoted-needle magnetic compass, but the modern need for stability and remote indication makes other methods desirable. Inductive devices, such as rotating coils, may be adapted to measure the intensity of the earth's field and hence its direction, and the development of simple instruments for this purpose is described, together with some systems of special interest.The need for a compact instrument has led to the development of detector units, or magnetometers, which have no moving parts, and static inductive devices—in which alternating exciting fields, combining with the earth's field, act upon iron-cored elements—now replace rotating coils in modern instruments.It is essential that any such device be stabilized against acceleration effects, and the merits and use of both vertical and azimuthal stabilization are discussed.Data transmission of heading is, of course, an essential feature of such compasses, and present-day methods of this are briefly described.

DOI:10.1049/pi-2.1951.0134

出版商:IEE    

年代:1951

数据来源: IET

摘要:

The fundamental requirements for the satisfactory dimming of low-pressure hot-cathode and cold-cathode fluorescent lamps are discussed. D.C. operation is first considered, and the treatment is then developed to cover a.c. circuits. Lamp stability is considered from the points of view of smooth control of current, supply-voltage variation, and intermittent extinction. Lamp circuits are generalized in terms of Thévenin's theorem, and the ideas of voltage control and impedance control are introduced. Practical circuits are discussed, the difficulties of multiple-lamp control, and the means for overcoming these, being mentioned. The separate-impedance method of control is described by reference to several circuits, and methods of unifying the control are suggested.

DOI:10.1049/pi-2.1951.0137

出版商:IEE    

年代:1951

数据来源: IET

摘要:

Practical methods of predetermining the transient performance of synchronous generators have in the past been based more on general considerations than on a strictly logical theory. On the other hand, general equations for the synchronous machine were derived by R. H. Park and are well known, but the equations have not been widely used in practice because a direct solution is laborious. The paper shows how, by making a number of approximations, simple solutions of the equations can be obtained for short-circuit and other fault conditions, both for the generator by itself and when it is operating with an external power system, assuming the circuits to remain balanced.The formulae obtained for the transient reactances and time-constants agree, in the main, with those deduced from general considerations. The present treatment, however, demonstrates clearly what are the underlying approximations, and shows what simplifications can be made when some of the components of the transient currents can be neglected.

DOI:10.1049/pi-2.1951.0140

出版商:IEE    

年代:1951

数据来源: IET