摘要:

In the problem of designing installations in which vessels or pipes of mild steel are heated electrically to a temperature not greater than the Curie point, either by conducting into or by inducing in them alternating current at supply frequency, the electrical engineer appears to find little practical assistance in published work. The paper gives some details of actual installations and the empirical formulae developed by the author from numerous tests and used in the design of new installations.In each example the required design values are given explicitly in terms of the data of the installation.

DOI:10.1049/pi-2.1952.0030

出版商:IEE    

年代:1952

数据来源: IET

摘要:

The elements and organization of an experimental magnetic storage system are described. A rotating wheel is used to give high transfer speeds and relatively short access time to data which are transferred directly to the high-speed cathode-ray tube store of a digital computer. The wheel is run in synchronism with the fundamental frequency of the computer under the control of a servo mechanism. A plated layer of pure nickel is used as the recording medium. A lowimpedance type of head combined with a new method of digital representation have been employed for the storage of data.A complete storage system of this type with a capacity of 3 000 numbers, each of 40 binary digits, has been incorporated in the Manchester University computer.

DOI:10.1049/pi-2.1952.0031

出版商:IEE    

年代:1952

数据来源: IET

摘要:

Recent proposals for the construction of universal high-speed digital computing machines have led to a demand for computing circuits for use in such machines. The paper discusses circuits for use with numbers expressed in serial binary form. Special reference is made to a machine in which the storage of binary numbers is achieved by the use of charge-patterns on the screens of cathode-ray tubes.

DOI:10.1049/pi-2.1952.0032

出版商:IEE    

年代:1952

数据来源: IET

摘要:

A graphical analysis is developed for the solution of second-order differential equations for systems with non-linear damping and restoring forces and with arbitrary drives. The construction for the general type of differential equation is shown, the errors are discussed, some practical problems are evaluated and the results are compared with experimental solutions or those from other methods.

DOI:10.1049/pi-2.1952.0036

出版商:IEE    

年代:1952

数据来源: IET

摘要:

A system is described where both the coarse and the fine measuring elements normally employed in a high-precision position-control servo mechanism can be used simultaneously without the need for switching from coarse to fine. The steady-state accuracy of the whole mechanism is the same as that of a conventional coarse-fine changeover system. The stability of the new system is sensibly that which would be obtained using only the coarse measuring elements.

DOI:10.1049/pi-2.1952.0039

出版商:IEE    

年代:1952

数据来源: IET

摘要:

The authors have developed a very simple new test for measuring, as a separate quantity, the harmonic-frequency losses in squirrel-cage or slip-ring motors. The new test has the special merit that it uses only apparatus available in every routine-test department. Its principle is discussed first, and then certain operating points are considered.To establish the validity of the new test, several slip-ring machines were tested both by the new method and by two other existing methods. Of the three methods, only the new one can be applied to squirrel-cage motors; and, to illustrate this application, a summary of test results for a large number of medium-sized industrial squirrel-cage motors is given. Appendices on corresponding stator and rotor voltages, and on hysteresis drag, conclude the paper.

DOI:10.1049/pi-2.1952.0043

出版商:IEE    

年代:1952

数据来源: IET

摘要:

The paper calls attention to the help which statistical technique can give to the commercial and engineering sides of electricity supply.A brief examination of the scope of the statistical approach shows that this technique is the key to many problems ranging from the action to be taken against hostile aircraft to the co-ordination of insulation. It enables experiments carried out “in the field” to be analysed, as it is possible with suitable planning of experiments to separate subsequently the various factors affecting a result.After a very condensed summary of the more generally used statistical methods, the application of some of these to generating stations and transmission systems is illustrated, particularly in connection with assessment of plant reliability.The present emphasis on planning to meet future loads makes forecasting a very important item. The Section dealing with this includes the effect of weather conditions on system load.The margin for random selection to be allowed in the setting of relays is considered; it is also shown how, in calculating the capacity of low-voltage lines, probability considerations directly affect the comparison between single- and multi-phase systems, and how statistical technique helps toclarify investigations into the voltage actually received at consumers' premises, and the reliability of various methods of earthing.It is suggested that rigid plus-and-minus limits may not always be the correct method of specifying restrictions on voltage drop. The argument of rigid limits is extended to meter testing, and by way of contrast the technique used in radio-interference testing is described.In dealing with matters affecting the consumer a prime consideration is the question of tariffs. Methods of gauging the effect of such changes in tariffs are indicated. The difficulty of ascertaining details about consumers' installations is greatly reduced by sampling. The use of sampling to enumerate details of the distribution system is referred to earlier in the paper.The importance of diversity, from the points of view both of tariffs and of system design, needs little stressing. Various methods of estimating diversity from knowledge of the consumer's load are discussed.Finally, one example of the replacement of wasting assets—street lamps—is analysed to show that planned replacement before the assets have worn out may be the most economical plan in certain circumstances.

DOI:10.1049/pi-2.1952.0044

出版商:IEE    

年代:1952

数据来源: IET

DOI:10.1049/pi-2.1952.0050

出版商:IEE    

年代:1952

数据来源: IET

DOI:10.1049/pi-2.1952.0051

出版商:IEE    

年代:1952

数据来源: IET

DOI:10.1049/pi-2.1952.0052

出版商:IEE    

年代:1952

数据来源: IET