摘要:

After a brief review of previous work on the propagation of surge voltages through machine windings, the fundamental differential equations for the propagation of waves through a winding with two coil sides per stator slot are derived. These show that all component frequencies of an incoming wave below a certain critical frequency are propagated through the winding with velocities which are dependent on the frequency. For super-critical frequencies the winding behaves as a condenser whose capacitance diminishes with increasing frequency. Various modes of winding are discussed, together with their effects on the impulse-voltage distribution.Test results on a typical machine are described and the voltage distribution explained with the aid of the fundamental theoretical deductions. The surge impedance of a large 11-kV alternator is about 80 ohms. Evaluation of the inductance for one of the machines tested shows that the majority of the flux produced by the surge current surrounds both conductors in the slot and must therefore be carried by the iron. This is also borne out by the fact that the removal of the rotor decreases both the self and mutual inductances of the windings, owing to the increased reluctance of the flux path.

DOI:10.1049/pi-2.1953.0138

出版商:IEE    

年代:1953

数据来源: IET

DOI:10.1049/pi-2.1953.0140

出版商:IEE    

年代:1953

数据来源: IET

摘要:

The paper deals with the use of voltage transformers as multipliers for complex quantities and describes how they may be used to form a network analyser. The analyser consists of a measuring section and a number of identical panels each containing two multiplying units. These panels may be used to represent impedances, admittances, voltage or current sources, phase-shifting auto-transformers or mutual inductances. Valuable features of the analyser are the ease with which negative resistance and unilateral mutual inductance may be introduced. The accuracy of the analyser depends on the suppression of amplitude and phase errors in the voltage ratios of the transformers, and each transformer is supplied with the required exciting current from special compensators.The paper concludes with examples of the principles to be adopted in applying the analyser to common problems concerning the behaviour of power networks, electrical machines and closed-loop control systems as well as to the solution of linear simultaneous equations.

DOI:10.1049/pi-2.1953.0141

出版商:IEE    

年代:1953

数据来源: IET

摘要:

The new universal high-speed digital computing machine now working at the Computing Machine Laboratory, Manchester University, is described. It has a high-speed storage capacity of 10 240 binary digits and an intermediate storage capacity of over 280 000 binary digits. Its other features include a completely automatic transfer system between the two types of store; a B-tube which allows instructions to be modified in a much shorter time than by normal accumulator use, thus facilitating the programming of iterative processes; and a fast multiplier which carries out a multiplication in the same order of time as the normal addition or subtraction operations. Input and output operations in this machine utilize normal 5-hole teleprinter tape. Input is by way of a photoelectric reader and output can occur either from a tape punch or a teleprinter, or both can operate together. The method of maintenance and also some reliability figures are given.

DOI:10.1049/pi-2.1953.0145

出版商:IEE    

年代:1953

数据来源: IET

摘要:

Details are given of the design and construction of the new universal high-speed digital computing machine now working at the Computing Machine Laboratory, Manchester University.The constructional techniques adopted for the electronic equipment, the cathode-ray-tube storage units and the magnetic storage drum are described, and an outline is given of the design procedures adopted for the electronic circuits. The techniques used to obtain reliability and ease of maintenance are particularly stressed. The development of suitable maintenance procedures for the operation of the computer continuously over periods of five days in each week is discussed, and details are given of the performance of the computer over a period of some 61 weeks.

DOI:10.1049/pi-2.1953.0146

出版商:IEE    

年代:1953

数据来源: IET

摘要:

The paper describes three methods of storing decimal digits, which are extensions of the well-known method of storing binary digits using a cathode-ray-tube store.7It is shown that one of these methods, which uses ten separate but small elements of the cathode-ray-tube screen, provides the best compromise between speed of operation, digit storing capacity and reliability.A complete serially-controlled cathode-ray-tube store holding 32 words of 8 decimal digits has been operated successfully. The digit period was 40 microsec, and could be conveniently reduced to 30 microsec if desired. These results compare favourably with those for the binary store used in the Manchester University computing machine.In the Appendix it is shown that the preferred decimal system may be derived from a new binary system of storage.

DOI:10.1049/pi-2.1953.0147

出版商:IEE    

年代:1953

数据来源: IET

摘要:

The paper is essentially in three parts. The first part deals with current practice at Manchester University, and, in particular, with modifications to the defocus-focus system of storage and the signal amplifier. The second part deals with experimental work directed towards the clarification of the mechanism of storage. The third part expounds a qualitative theory based on the experiments described in the second part. Experiments have been performed to obtain information relevant to the following controversial points:(a) The existence of electron-cloud pulses.(b) The effect of variation in the speed of the edges of the cathode-ray-tube grid waveform.(c) The mean potential of the cathode-ray-tube screen surface.(d) The depth of a well.(e) Possible variation of well depth with beam current.It is concluded that storage operation may be theoretically explained by drawing an analogy with a triode valve; the collector, the bombarded spot and the surrounding screen surface being analogous to the anode, cathode and control grid, respectively.For technological purposes the original theory1 may well be sufficient, and it is shown that it can be used to predict storage results.

DOI:10.1049/pi-2.1953.0148

出版商:IEE    

年代:1953

数据来源: IET

摘要:

A magnetometer is described which was designed primarily for measuring a magnetic field within the confined space of a permeameter. The measuring head of the instrument contains a thin solenoid through which a direct current is passed, to balance the field being measured and produce zero field in the solenoid. A sensitive field detector within the solenoid consists of a fine ferromagnetic (Mumetal) wire carrying an alternating current of frequency 5 kc/s. This current develops a saturating circular field in the wire and causes its effective longitudinal permeability to alternate at twice the frequency of the current. A field along the wire thus produces an alternating induction in the wire and consequently an alternating e.m.f. in the solenoid; this e.m.f. therefore serves as a sensitive indication of field.With associated equipment designed especially for the magnetometer it is possible to detect a change in field strength of 2 × 10−5oersted. Alternatively the head can be used with standard laboratory equipment allowing a field of 2 × 10−3oersted to be detected. The maximum field strength that can be measured is limited to about 50 oersteds by the heat developed in the solenoid by the balancing current.

DOI:10.1049/pi-2.1953.0152

出版商:IEE    

年代:1953

数据来源: IET

摘要:

The general thermal characteristics of the cast-in-concrete type of reactor and the most effective ventilation arrangements are described, followed by an account of recent developments in boosted ventilation.Details are given of the increased performance obtainable by jet boosting, and the paper concludes with a description of actual installations in service and methods of control adopted.

DOI:10.1049/pi-2.1953.0153

出版商:IEE    

年代:1953

数据来源: IET

DOI:10.1049/pi-2.1953.0162

出版商:IEE    

年代:1953

数据来源: IET