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Electrical Engineers, Proceedings of the Institution of

Issue 7 • Date July 1963

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Displaying Results 1 - 25 of 30
  • Anglo-Canadian transatlantic telephone cable (CANTAT). Planning and overall performance

    Page(s): 1115 - 1123
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (1213 KB)  

    When the first transatlantic telephone cable was planned in 1953 there were two possible systems available: one American, using small-diameter flexible repeaters in two uni-directional cables, and the other British, using much larger, rigid repeaters in a single cable. The former was the more advanced, particularly with respect to laying methods in ocean depths, and was adopted for the main Atlantic crossing, the British system being used between Newfoundland and Nova Scotia. As early as 1951, the British Post Office had started development of a revolutionary type of coaxial cable for use in deep water. This had its strength member in the centre, torsionally balanced, and an external sheath of polythene; its non-twisting characteristics under tension promised major improvements in laying and recovery techniques. When, in 1957, the British and Canadian Governments agreed to provide a new submarine telephone cable between the two countries, British rigid repeaters with the new British Lightweight cable in deep water were envisaged. This cable system, known as CANTAT, was developed, manufactured and completed within a period of four years. In addition to overland connections in Great Britain and Canada to London and Montreal, respectively, there are two submarine cable links, one between Scotland and Newfoundland, providing 240 kc/s bandwidth in each direction (initially 60 telephone circuits recently increased to 80), and one in the Gulf of St. Lawrence providing 480kc/s bandwidth in each direction (initially 120 telephone circuits capable of increase to 160). The system was opened for service by Her Majesty The Queen in December 1961, and is, for the present, the most advanced installation of its kind. View full abstract»

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  • Anglo-Canadian transatlantic telephone cable (CANTAT). Cable development, design and manufacture

    Page(s): 1124 - 1133
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (1504 KB)  

    In 1951, the British Post Office evolved an entirely new type of deep-sea submarine telephone cable which was intended to overcome many of the serious disadvantages inherent in conventional wire-armoured cable. This new cable, known as the Lightweight cable because of its very light weight in water, was under exhaustive development for seven years before it could be accepted with confidence for a trans-ocean system. 1600 miles of this cable have now been laid on the Anglo-Canadian (CANTAT) system, and in all respects it has met the highest performance expectations. It has also proved to be much cheaper than a comparable conventional cable. Its electrical stability is noteworthy as it has exhibited a much smaller attenuation laying change than that experienced with previous cables, and, during the first year, there has been no significant indication of ageing. This type of cable is expected to be employed on all new deep-sea systems. View full abstract»

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  • Anglo-Canadian transatlantic telephone cable (CANTAT). Repeaters and equalization

    Page(s): 1134 - 1139
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (860 KB)  

    The paper describes the repeaters and equalization methods used on the CANTAT submarine telephone system between Oban (Scotland) and Corner Brook (Newfoundland). In contrast to previous submerged repeaters, a new valve was used in the amplifiers and the voltage drop across a repeater was about 70V¿a reduction of some 40% despite this, the greater number of repeaters in the cable increased the line voltage supply considerably, and the repeaters were designed to withstand a higher voltage between the inner unit and its housing. Because of the larger number of repeaters and greater difficulty in locating faults, a new supervisory method was adopted which could also locate noise faults. The equalizers, besides having basic networks, allow mop-up equalization to be performed on board ship during the lay. View full abstract»

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  • Anglo-Canadian transatlantic telephone cable (CANTAT). Repeater fault-locating equipment

    Page(s): 1140 - 1145
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (761 KB)  

    On a long, repeatered, submarine-cable link, it is essential that facilities are provided for the terminal-station staff to be able to monitor the performance of each repeater in the link. The paper describes the two types of monitoring equipment that have been designed and installed at the British and Canadian terminal stations of the CANTAT 90-repeater submarine link. One type of equipment uses a radar-type technique, and relies on the natural non-linearity of the repeaters for the return signals; it provides, in effect, a means for monitoring the non-linearity of the repeaters. The other equipment uses a selective frequency-changing device in each repeater for measuring from one terminal station the loop gain to, and the noise¿or intermodulation-generated by, any selected repeater. View full abstract»

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  • Anglo-Canadian transatlantic telephone cable (CANTAT). Power-feeding equipment

    Page(s): 1146 - 1150
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (690 KB)  

    A constant-current power system using permanent-magnet reference standards and magnetic-amplifier control circuits has been developed for energizing the Anglo-Canadian link (CANTAT). This system provides the necessary high degree of regulation of cable current, continuity of feed and protection for the submarine system. The protection circuits can be tested whilst the system is energized. The design is sufficiently flexible to make the equipment suitable for powering the majority of existing or planned systems using thermionic valve repeaters. View full abstract»

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  • Anglo-Canadian transatlantic telephone cable (CANTAT). Cable-laying gear

    Page(s): 1151 - 1158
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (1434 KB)  

    The paper describes the stern cable-laying gear and associated equipment developed for cable and repeater stowage, handling and laying on H.M.T.S. Monarch. The techniques and equipment described were used throughout the laying of the CANTAT cable and operated very satisfactorily under widely differing operational conditions. View full abstract»

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  • Anglo-Canadian transatlantic telephone cable (CANTAT). Laying the North Atlantic link

    Page(s): 1159 - 1164
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    CANTAT was the third telephone system to be laid across the Atlantic, but it was of a very different type from its predecessors and was unique in many ways. It was the first system to use the new Lightweight cable. A new equalization technique had to be introduced whereby system transmission misalignments encountered during the lay were corrected by suitable networks built and housed on the ship, without stopping the laying operation. Every effort was made to anticipate all possible eventualities, since the laying of any long ocean system is hazardous. The complete laying operation was spread over seven months, and although many incidents occurred none was abnormal, and no weaknesses were apparent in the equipment or the techniques. View full abstract»

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  • Interferometer direction finder for the H.F. band

    Page(s): 1165 - 1170
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (720 KB)  

    The inherent accuracy of the simple two-element interferometer of several wavelengths, spacing can be utilized if resolution of the phase ambiguity is obtained. The statistical probability of this in the presence of wave interference is estimated from observations on a narrow-aperture pair of elements. The design problems and system errors are discussed for a five-element direction-finding array. View full abstract»

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  • Precise absolute technique for measuring low-loss symmetrical linear passive 4-terminal networks at V.H.F. and U.H.F.

    Page(s): 1171 - 1180
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (1249 KB)  

    A technique of high absolute accuracy for measuring low-loss symmetrical linear passive 4-terminal networks is described. The method is well suited for the v.h.f. and u.h.f. ranges. The unknown network is inserted in turn near a high- and a low-impedance point along a low-loss uniform line short-circuited at each end. From measurement of the two resonant frequencies (coincident, or nearly so, by adjustment of line lengths) and knowledge of the line dimensions, the characteristic impedance Z0x and electrical length lx of the equivalent uniform line are computed. Errors are discussed and means suggested for reducing them. The technique has been explored in the frequency range 300¿2800 Mc/s, using precise 50¿ coaxial lines. Connectors, adaptors and small-range adjustable stubs, with reflections mostly less than 10%, have been measured. The r.m.s. scatter in the measured results is of the order of 0.1% in Z0x and 0.01 cm in lx. The absolute errors are estimated to be only a little greater. The method should apply over wider ranges of frequency and to a greater variety of unknowns, including waveguide two-ports. View full abstract»

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  • Surface effects on microwave signals propagating in semiconductors

    Page(s): 1181 - 1186
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (591 KB)  

    The effect of the variation of electrical properties at the surface on the propagation of a microwave signal through a semiconductor placed in a guide are analysed by a perturbation method. General expressions are obtained for the reflection and transmission coefficients of the semiconductor sample. The results of the analysis are discussed with reference to microwave measurement of the bulk and surface properties of semiconductors. View full abstract»

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  • Analysis of a current pulse generator regulated by a square-loop ferrite core

    Page(s): 1187 - 1190
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (348 KB)  

    Existing current-pulse-generator circuits are briefly discussed. For driving inductive loads, the circuit giving the least overshoot for a given rise-time has been found to be one in which the current is regulated by a square-loop core. Its operation is described, and the degree of overshoot calculated for the case of a load consisting of series resistance and inductance. A worked example is given. View full abstract»

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  • New and improved types of waffle-iron filters

    Page(s): 1191 - 1198
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (1454 KB)  

    Waffle-iron filters are waveguide low-pass filters with wide stop-bands. The waffle-iron filter was first described in 1957 in a report of the Stanford Research Institute, and upon this all subsequent designs have been based. The pass-band fractional bandwidths were generally in the order of 10¿20%, and the unpressurized pulse power-handling capacity was about 1.5 MW at the L-band. The stop-band attenuation was typically more than 60 dB from below the second harmonic to beyond the fourth harmonic frequency. New filters have recently been developed with pass-band fractional bandwidths of over 40% (covering almost the whole recommended frequency band of a standard waveguide) and pulse power-handling capacity, without pressurization, of up to about 8 MW at the L-band, while the stop-band attenuation and bandwidth remain as good as before. View full abstract»

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  • A new millimetre-wave method for determination of electron-density profiles in a linear discharge

    Page(s): 1202 - 1210
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (984 KB)  

    The method depends on probing the plasma column with a microwave beam incident obliquely on its boundary. Owing to electron-density gradients, the beam is continuously refracted inside the plasma column and finally emerges at a certain point on its boundary, where it is received. The position of that point for any particular angle of incidence can be related to the electron-density profile through a simplified theoretical model which is based on geometrical optics. According to this model, the determination of profile requires measurements at two angles of incidence. The experimental work was carried out on a linear pinched discharge at wavelengths of 8.9 and 4.3mm. The discharge took place in argon at a pressure of 23¿mHg using a capacitor-bank voltage of 6kV and an-energy of 3600J. Electron-density profiles could be determined during the afterglow period of the discharge. It was not possible, however, to determine profiles during the pinch owing to insufficient time resolution. View full abstract»

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  • Millimetre-wave diagnostics of a pinched linear discharge

    Page(s): 1211 - 1220
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    Experiments were carried out using 8.9 and 4.3 mm radiation to explore the properties of a pinched discharge between plane electrodes. The discharge had a maximum energy of 10kJ at 10kV and took place in argon at pressures of 75 and 300¿m Hg. Millimetre-wave radiation was directed on to the discharge tube normal to its axis, and the transmitted and reflected signals were recorded. Analysis of these records gave detailed information about the times of certain changes in the plasma, not only during the afterglow but also during the much shorter period of current flow when pinching, if any, occurred. Observations were, in general, found to be independent of the shape of the incident beam, but were critically dependent on the gas pressure and therefore on the flow rate and the discharge-repetition frequency. Other measurements-of voltage, current and luminosity-were used as required to augment and compare with the millimetre-wave results: where comparison could be made, the agreement was good. View full abstract»

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  • Recent improvements in transformer analogue network analysers

    Page(s): 1235 - 1242
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    A new form of transformer analogue network analyser which has been developed in the power systems laboratory of the Manchester College of Science and Technology is described. A number of new features are included, such as a polar generator unit and an entirely new type of metering system employing two-element dynamometer instruments. Sources of error in computing transformers are discussed, and the design of a transformer operating at 400 c/s, together with a transistorized linear compensator, is presented. Stability of linear and non-linear compensators, and centralized connection systems using a plugging-up board, are discussed in Appendices. View full abstract»

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  • American practice in d.c. insulation testing

    Page(s): 1243 - 1248
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (721 KB)  

    The testing of electrical machinery, so that it may be withdrawn from service and re-conditioned at a time when continued operation might result in breakdown, is of great importance. Various methods are used, and among them is the testing of the insulation by the application of a direct voltage. This has been the subject of much discussion, but such methods are used extensively in the United States, despite their admitted shortcomings. In the paper brief descriptions of two of these methods are given, together with examples of their applications. It is suggested that these methods could well repay further study. View full abstract»

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  • Operation of several induction motors with a common rotor resistor

    Page(s): 1249 - 1254
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (615 KB)  

    The mode of operation described in the title is employed as a simple means for maintaining equality between the speeds of a number of separately driven shafts. The paper contains a theoretical study of such an operation; it brings to light the general nature of the phenomena concerned, and contains formulae which would make possible the calculation of the rotor resistor appropriate to a variety of prescribed conditions. View full abstract»

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  • Simplified presentation of the eddy-current-loss equation for laminated pole-shoes

    Page(s): 1255 - 1259
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (449 KB)  

    The paper is concerned with the simplification of the equations governing tooth-ripple eddy-current loss at a laminated pole-face in the form in which they were stated in an earlier paper by Greig and Sathirakul (see 108 C, p. 130). The equations are quite complicated and their numerical evaluation can involve considerable labour. Computed data in either graphical or tabular form are necessarily cumbersome and voluminous, unless represented in non-dimensional form. It is shown that a satisfactory non-dimensional presentation of tooth-ripple eddy-current losses can be achieved by computing, for the required range of the relevant parameters, the ratio of the loss per unit area of laminated pole-face to that which would occur if the pole were not laminated. View full abstract»

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  • Growth of discharges on polluted insulation

    Page(s): 1260 - 1266
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    The voltage required to maintain local discharges on polluted insulation may increase with increase in discharge length, and if this voltage exceeds the supply voltage, the discharges extinguish without causing a flashover. An analysis based on this mechanism has been made for the simplified case of an insulator having a constant surface resistance, rc, per centimetre of leakage path. This has shown that the flashover stress, Ec, is proportional to p0.43, where p is the resistivity of the pollution, and that the maximum leakage current which can flow when flashover is impossible is 233Ec¿1.31 amperes, Ec being in volts (peak) per centimetre. It has been found that these conclusions apply to conventional bushings subjected to wet-flashover tests, and to power insulators subjected to natural pollution under service conditions. Further confirmation of the analysis was obtained from experiments made by the authors and previous workers with artificial pollution, deposited so as to maintain rc constant along the surface. The agreement between this analysis and the experimental results of several investigators indicates that the mechanism discussed here controls flashover in many instances. View full abstract»

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Aims & Scope

The Proceedings of the Institution of Electrical Engineers was published by the IET between 1963 and 1979.

Full Aims & Scope