Control Gear Research Articles

The Development and Application of Metal Halide Lamps for Color Filming and Television

The development of high-pressure discharge lamps over the years has been aimed at improving color rendering, efficiency and life. The compact-source iodide (CSI) lamp was initially developed in 400-W and 1,000-W ratings for projector applications, but it was the new demands of outside broadcast color television in 1969 that led to the introduction of this lamp housed in a PAR-64 sealed-beam globe for floodlighting sports stadia from high corner towers. Sports areas with sidelighting were not so well suited to the use of the symmetrical beam CSI floodlights, so another metal halide lamp was introduced — this one with an unjacketed linear arc tube — in 750-W and 1,600-W ratings. For filming, the 1-kW lamp performs exceptionally well as a fill-in source with daylight. At 90 lm/W, it is five to six times more efficient than tungsten-halogen lamps used with blue filters to correct the daylight; four lamps are approximately equivalent to a 225-A brute arc. Control gear is being made simpler and more versatile, and the problem of “beat,” which is already controllable in filming situations, is expected to be overcome completely with techniques now being developed.

The Automatic Start Up and Shut Down of a Mains Frequency Plasma Torch and its Instrumentation

This paper describes an automatic control system for the start up and shut down of a 415V., 100kW. mains frequency plasma torch which has been developed [1] at the University of Aston in Birmingham. Instrumentation of the main input and output parameters is provided from a centrally-located panel. In view of the large power to be controlled, it is essential that the cooling water and electrical supplies are switched in the correct order both when starting up and shutting down, and the protection requirements necessitate ``fail-safe'' operation of the control gear under fault conditions. This automatic operation represents a significant improvement upon the original control system, which was manually operated. A closed-loop control of the outlet temperature by regulating the air flow is described elsewhere [2]. Measurements of the efficiency of the torch in converting electrical energy to heat have also been published [3].

Reflections on changing standards in motor control gear

Today's engineer is faced with a multiplicity of standards which he has first to understand and then to incorporate in his designs. For the British motor-control-gear engineer, an appreciation of the relation between British Standards and IEC recommendations is vital

Increasing efficiency

As part of a research and development programme, the Royal Aircraft Establishment at Farnborough has been continuously testing components and materials for Concorde. To simulate the calculated extremes of heat, pressure and stress expected in flight from ground level to ten miles high, at twice the speed of sound, A.E.W. Ltd were asked to design and build special test ovens and electronic control gear. Specifying very close limits to tolerance on all aspects of design, the overriding stipulation called for reliability and continuous operation on programmes of 30,000hr (3½ year) duration.

British Railway's experience with electronic control gear on locomotives: 1966–1968 : G. G. Kibblewhite, IEE Conf. Reliab. Electron., Conf. Publ. No. 60, 10–12 December (1969), p. 57

British Railway's experience with electronic control gear on locomotives: 1966–1968 : G. G. Kibblewhite, IEE Conf. Reliab. Electron., Conf. Publ. No. 60, 10–12 December (1969), p. 57

Some aspects of the classification of nuclear ships

Three sets of conditions taken into account by the Classification Society for nuclear merchant ships are: (1) the ship must be protected, (2) the crew is not to be exposed to undue hazards, (3) when the ship is in port the general public is not to be exposed to undue hazards. Of greatest importance is the nature of the potential risk existing in the operation of a nuclear reactor. Any accident involving radiation hazards would certainly imply a wide emotional reaction by the public. Fuel element classification involves two principles: (1) nuclear factors which give the highest values of the neutron flux at characteristic spots, and (2) technological factors which take care of fabrication tolerances, deformations of the element in operation, coolant flow variations and accuracy and time lapse of the reactor control gear. Various conditions which need to be understood for proper classification of the pressure vessel and containment vessel are discussed, with great emphasis placed on the safety of operation outlined in the present classification systems. Present methods of examination of nuclear plants, including the use of ultrasonics, give results which aid in classification during the fabrication process. R&D programs are currently under way in some places to investigate in a more accurate manner the behavior of reactor systems under fault or accident conditions.

Pole-changing motor using π-spread phase windings

A new method is described for pole changing 3-phase windings where one of the basic pole-pair numbers is a multiple of 3. Using the method, a 4/6-pole cage induction motor with a 36-slot stator winding is a standard machine at 4 poles but has a phase spread of π radians at 6 poles. There is no unbalance between the phases or troublesome harmonic effects. Though the number of winding terminals to be brought out is 12, the control gear required is essentially a 3-phase double-throw switch, with two additional rows of terminals on one side. The material is supported by tests with an experimental 4/6-pole motor.

Pole-changing motor using π-spread phase windings

A new method is described for pole changing 3-phase windings where one of the basic pole-pair numbers is a multiple of 3. Using the method, a 4/6-pole cage induction motor with a 36-slot stator winding is a standard machine at 4 poles but has a phase spread of π radians at 6 poles. There is no unbalance between the phases or troublesome harmonic effects. Though the number of winding terminals to be brought out is 12, the control gear required is essentially a 3-phase double-throw switch, with two additional rows of terminals on one side. The material is supported by tests with an experimental 4/6-pole motor.

Cement Making in India

The Indian cement industry has shown remarkable growth, and under the fourth Five-Year Plan, by the end of 1971, it is expected that the annual production capacity will be approximately 25-26 million tons. The available limestone reserves, the main raw material, are estimated to be about five billion tons. The principal fuel, coal, is also available. Both dry and wet manufacturing processes are adopted. Cement making machinery and electrical motors and control gears are also being manufactured in India. Marketing and sales are handled through the State Cement Corporation; prices are controlled. India, though the second largest country in the world, is the poorest of the nations. In spite of this, India's record of economic development under the Five-Year Plan is satisfactory.

Marine Steam Turbines

The reasons are examined for the present increase in the number of marine propulsion turbines being ordered. The design of a range of turbines is discussed, with particular reference to single-cylinder turbines, control gear, and reduction gearing. It is shown that parallel developments are taking place in the design of marine turbine-generator sets, which, due to increases in running speeds, have increased in efficiency and decreased in size and cost.

Industrial Electric Motors and Control Gear

Industrial Electric Motors and Control Gear

Three-speed single-winding single-phase induction motor

The pole-amplitude-modulation method of obtaining economic and efficient 2-speed and 3-speed operation of a normal 3-phase squirrel-cage induction motor with a single winding, developed by Rawcliffe and Fong, has been applied to the single-phase induction motor.The paper describes the theory and design methods, and presents experimental results obtained with a 3-speed 8/6/4-pole single-phase test motor. Performance of the motor at 6 poles and 4 poles is comparable with that of normal single-phase motors, while at 8 poles it is somewhat inferior. The winding is of a perfectly standard type. Ten terminals only are required for two speeds, and 12 terminals for three speeds, the control gear therefore being extremely simple.

The joint AN/CNEN/NPPC irradiation programme

An account is presented of the development of the Joint AN/CNEN/NPPC Irradiation Programme, originally mounted in 1959 and which has since made considerable progress in its objective to study the irradiation behaviour of uranium and uranium alloys in the Italian Ispra-1 reactor. A description is given of the irradiation rigs and their associated instrumentation and control gear, together with facilities established in Newcastle to construct and test such rig equipment. The irradiation facilities of the Ispra-I reactor which are relevant to the programme are described, and operating experience with the first two irradiation charges is discussed. The post-irradiation facilities at Ispra and in the CNEN hot laboratories at Casaccia are also described, and handling experience with the first charge is summarized.

Wide-ratio two-speed single-winding induction motors

Previous papers have described the principle of pole-amplitude modulation (p.a.m.), and its application to produce 2-speed single-winding squirrel-cage induction motors. The original theory and practice referred, specifically, to close-ratio speed changing only.This paper discusses p.a.m. on the basis of ampere-conductor distribution; and it extends its application to a considerable range of wide-ratio speed-changing induction motors. Two particular pole ratios, 4/1 and 5/1, are considered in detail, by way of example.In every case, a double-layer winding with all coils identical is used; and, in all but a very few applications, six control leads and very simple standardised control gear are required. Sample test results—particularly of the accelerating characteristics—are given, the machines being, in every case, fully up to normal industrial standards.

Three-speed single-winding squirrel-cage induction motors

A 2-speed single-winding squirrel-cage induction motor, with only six terminals and of excellent rating and performance, has been described in several previous papers. The same principles have now been extended to give a 3-speed motor of comparable quality. Only twelve terminals and reasonably simple control gear are required for three speeds. Almost any speed combination can be obtained, the example given in the paper being a motor for 6/8/10 poles, particularly suitable for fan or pump drives.

An automatic continuous denier recorder for synthetic textile yarns

Measuring the diameter of a fine textile filament by its electrical capacitance effect between the fixed plates of a capacitor presents the twin problems of the very small capacitance change to be measured and the high degree of stability to be maintained in the capacitor.The present instrument is insensitive to changes in the standing capacitance and achieves this by vibrating the yarn in and out of the gap. The capacitance between the two electrodes is therefore varying at the frequency of the vibrating yarn, and a variable capacitor is switched into circuit in phase with the yarn and used to balance this change in capacitance in a bridge circuit. The output from the bridge is amplified and used to drive a motor which balances the bridge by adjusting the variable capacitor. The movement of the motor also drives a pen recorder. The bridge circuit conveniently provides several measuring ranges and allows the measuring head to be one of several connected to the main instrument by long cables.Synthetic-fibre manufacture involves numerous identical production units in parallel. Monitoring and control gear is therefore fed from a multiplicity of transducers which must be matched, reliable and capable of simple routine test and replacement without upsetting their related circuits.

An attachment for mechanizing linear measurements

The optimum method of mechanizing production measurements of dimensional parameters in engineering, especially under conditions of small-scale mass production in small establishments, consists in the use of universal checking devices which comprise a set of independent compound units, whose production must be undertaken by our instrument-making industry. This solution of the problem frees the customer plants from the necessity of producing special equipment, since they will only have to choose the measuring arrangement and a set of units whose various combinations can be used for checking details of any given type. This method will raise the quality of the control gear and lower its cost, will reduce to a minimum the time required for its assembly and familiarization with its measurement techniques; it will simplify the organization of inspection and speed the measuring.

An automatic continuous denier recorder for synthetic textile yarns

Measuring the diameter of a fine textile filament by its electrical capacitance effect between the fixed plates of a capacitor presents the twin problems of the very small capacitance change to be measured and the high degree of stability to be maintained in the capacitor.The present instrument is insensitive to changes in the standing capacitance and achieves this by vibrating the yarn in and out of the gap. The capacitance between the two electrodes is therefore varying at the frequency of the vibrating yarn, and a variable capacitor is switched into circuit in phase with the yarn and used to balance this change in capacitance in a bridge circuit. The output from the bridge is amplified and used to drive a motor which balances the bridge by adjusting the variable capacitor. The movement of the motor also drives a pen recorder. The bridge circuit conveniently provides several measuring ranges and allows the measuring head to be one of several connected to the main instrument by long cables.Synthetic-fibre manufacture involves numerous identical production units in parallel. Monitoring and control gear is therefore fed from a multiplicity of transducers which must be matched, reliable and capable of simple routine test and replacement without upsetting their related circuits.

Magnetic field strength in oersteds near large rectangular conductors

A high value of direct current in a conductor produces a high magnetic field which may affect electromagnetic instruments and control gear in the vicinity. The value of the magnetic field in oersteds at a distance d in feet, from the center of a large round conductor, solid or tubular, carrying a current of I amperes is given very simply by the equation, $H = 0.00656 \, I/d \eqno {\hbox{(1)}}$.

Light Mechanical Engineering in South Wales

Light mechanical engineering in South Wales began to develop about 1938, and this paper describes the following typical modern products offering notable design, production, and operational features. Diaphragm valves with control gear and modern impervious materials; turbine type flowmeters and fuel/water separators; the manufacture of washing machines; watches and clocks; circuit assemblies for digital computers; and some details of test rigs and plant used in chemical and textile process industries.