Universal motors

Segment plate, used as insulation between copper commutator segments on direct-current universal motors and generators, accounts for the primary use for built-up mica. Phlogopite built-up mica is preferred for these segments because it wears at the same rate as the copper segments. 

Universal Motors. A universal motor is a series-wound motor designed to operate at approximately the same speed and output on either direct current or single-phase alternating current of a frequency not greater than 60 cycles/s and approximately the same rms voltage. There are two types ... 

Reversal of rotation may be achieved by reversing the connections of either the field or armature windings but not both. This characteristic means that the machine will run on both a.c. or d.c. and is, therefore, sometimes referred to as a universal motor. 

In an electric motor an electric current and magnetic field produce a turning movement. This can drive all sorts of machines, from wrist watches to trains. The motor shown in Fig. 1 is for a washing machine. It is a universal motor, which can run on direct current or alternating current. 

When a universal motor is run on direct current, the magnetic poles in the armature change while those of the field magnet remain constant. 

Universal Motors. Universal motors are essentially series motors that operate with nearly equivalent performance on direct current or alternating current up to 60 Hz. They differ from dc series motors in that they have different winding ratios and thinner iron laminations. A dc series motor runs on alternating current, but inefficiently. A universal motor, however, runs on direct current with essentially equivalent ac performance, but with poorer commutation and brush life than an equivalent dc series motor. 

A universal motor has the highest horsepower per pound ratio of any ac motor because of its abihty to operate at much greater speeds than any other 60-Hz motor. It is ideally suited for operation at a rated output, where an occasional overload or intermittent heavy load occurs. Stall torque may be as much as 10 times the continuous rated torque. The motor may even be operated in a stalled condition for short periods of time. 

High starting torque, adjustable-speed characteristics, small size, and economy are all advantages of the universal motor. Universal motors are not more widely used, however, because their operating hfe is shorter, their size range is limited [to about 2 hp (1.5 kW)], and their very high speeds hmit their apphcations. 

Universal motors can be built to deliver speeds ranging from 4000 to 24,000 r/min and rated power from 0.1 to 1 hp (75 to 750 W). Efficiency varies from 30 percent for smaU sizes to 75 percent for large sizes. 

Voltage variation up to 6 percent of rated voltage for universal motors and 10 percent of rated voltage for ac and dc motors... 

Appiications actuators, fan motors, fuel pumps, garden appliances, HVAC motors, household appliances, photoresists, power tools, universal motors, window lift motors, wiper motors ... 

A series motor will run on both a.c. or d.c. and Is, therefore, sometimes referred to as a universal motor. 

In order to characterize the behavior of motor fuels or their components with regard to knocking resistance but without involving chemical composition criteria which are complex and not easy to quantify, the traditional method that has been universally employed for more than 50 years consists of introducing the concept of octane number. 

Figure C3.1.2. Stopped-flow apparatus with motor-driven syringes. Syringe plungers force tire reactants A and B tlirough a mixing chamber into a spectral cell. Kinetic data collection begins when tire effluent syringe plunger is pushed out to contact an activation switch, about a millisecond after tire initiation of mixing. (Adapted from Pilling M J and Seakins P W 1995 Reaction Kinetics (Oxford Oxford University Press)...

W. Carter, Ocyone Reactivity Analysis of Emissionsfrom Motor Vehicles, (Draft Report for the Western Liquid Gas Association), Statewide Air Pollution Research Center, University of California at Riverside, July 11, 1989. 

MG-I Reference to a publiealion on Motors and Generators by NEMA (National Electrical Manufacturers Association. USA) which is adopted universally. 

The motors are universally designed for an ambient temperature of 40°C according to lEC 60034-1, unless specified otherwise. For temperatures below 40°C, the motor will run cooler by the amount the ambient temperature is lower. To utilize a higher output because of lower ambient temperature may, however, not he worthwhile. 

For a lower range of motors, say up to a frame size of 355, the silicon steel normally used for stator and rotor core laminations is universally 0.5-0.65 mm thick and possesses a high content of silicon for achieving better electromagnetic properties. The average content of silicon in such sheets is of the order of 1.3-0.8% and a core loss of roughly 2.3-3.6 W/kg, determined al a flux density of I W[ym and a frequency of 50 Hz. For medium-sized motors, in frames 400-710, silicon steel with a still better content of silicon, of the order of 1.3-1.8% having lower losses of the order of 2.3-1.8 W/kg is prefeired, with a thickness of lamination of 0.5-0.35 mm. 

Please notice that in a well-ventilated laboratory and a pressure cell, these experiments can be executed safely. In seven years of graduate research activity at the Chemical Engineering Department of the University of Akron, only one catalyst ignition and one real CO alarm occurred. Several false CO alarms were sounded until someone noticed that they always happened about 2 30 PM. As it turned out, one maintenance employee parked his old car right in front of the air intake to the lab ventilation. He warmed up his car for a while before he started to go home after his shift, and the motor exhaust gas set off the false alarms. 

Peter C. Eklund, Department of Physics and Astronomy and Center for Applied Energy Research, University of Kentucky, Lexington, Kentucky 40506, USA Philip J. Johnson, Ford Motor Company, Automotive Components Division, Schaefer Court 11, 14555 Rotunda Drive, Dearborn, Michigan 48120, USA Costa Komodromos, Gas Research Centre, British Gas, Ashby Road, Loughborough, Leicestershire LE11 36U, United Kingdom Max L. Lakt, Applied Sciences, Inc. 141 West Xenia Avenue, Cederville, Ohio 45314, USA... 

In 1819, Hans Christian Oersted, professor of physics at Copenhagen University, discovered that a magnet experiences a force when in the vicinity of a wire carrying an electric current. The fact that the magnet experiences a force is evidence that the electric current produces a magnetic field, which eventually led to the development of innumerable devices— electric motors, electric generators, speakers for In-... 

Standard. Advise mounting position vertical, horizontal, wall, etc. (Some motors cannot be mounted other than horizontal because of bearing and/or lubrication arrangements without special provisions. Others are universal mounted, and still others can be suitably modified in the field.)... 

Serious research in catalytic reduction of automotive exhaust was begun in 1949 by Eugene Houdry, who developed mufflers for fork lift trucks used in confined spaces such as mines and warehouses (18). One of the supports used was the monolith—porcelain rods covered with films of alumina, on which platinum was deposited. California enacted laws in 1959 and 1960 on air quality and motor vehicle emission standards, which would be operative when at least two devices were developed that could meet the requirements. This gave the impetus for a greater effort in automotive catalysis research (19). Catalyst developments and fleet tests involved the partnership of catalyst manufacturers and muffler manufacturers. Three of these teams were certified by the California Motor Vehicle Pollution Control Board in 1964-65 American Cyanamid and Walker, W. R. Grace and Norris-Thermador, and Universal Oil Products and Arvin. At the same time, Detroit announced that engine modifications by lean carburation and secondary air injection enabled them to meet the California standard without the use of catalysts. This then delayed the use of catalysts in automobiles. 

We have included in this volume two chapters specifically related to society s kinetic system. We have asked James Wei of the University of Delaware, recent Chairman of the consultant panel on Catalyst Systems for the National Academy of Sciences Committee on Motor Vehicle Emissions, to illustrate key problems and bridges between the catalytic science and the practical objectives of minimizing automobile exhaust emissions. We have also asked for a portrayal of the hard economic facts that constrain and guide what properties in a catalyst are useful to the catalytic practitioner. For this we have turned to Duncan S. Davies, General Manager of Research and Development, and John Dewing, Research Specialist in Heterogeneous Catalysts, both from Imperial Chemical Industries Limited. 

In contrast, the latest DC motors are very powerful and with integral feedback they also exhibit close speed control to 2 rpm within range 50-700 simple indications of speed and motor load are also possible. The trials of two such home-made units around the laboratories have met with enthusiastic and universal welcome, a clear sign of incipient demand for their commercialisation. 

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