Integral Horsepower Research Articles

Design Considerations for the Use of Aluminum Alloys for Integral Horsepower Motors

The design considerations on the use of aluminum alloys for the external supporting parts of integral horsepower induction motors are compared with the previously conventional use of cast iron. Covered are such factors as type of aluminum alloy selected considering service requirements and manufacturing methods planned, strength, reliability, durability (including corrosion resistance), effect on overall weight and performance. The tests made to check suitability of actual results against design plans are briefly described. In addition, the considerations and tests required to use aluminum windings alternatively with copper are discussed.

Engineering Test Codes and Standards for Motors, Controllers, Switchgear, and Transformers

There are many standards, which apply to electric equipment, such as ANSI, IEEE, NEMA, UL, and IEC. These standards cover factors such as design, installation, performance, and testing of both components and assemblies of components. To consider all of these factors would be a major undertaking. Only the performance and conformance testing of assemblies such as induction and synchronous motors in integral horsepower ratings, controllers for 600-V and 5000-V classes, low-voltage and medium-voltage switchgear assemblies, and transformers for load centers and substations are covered. The tests which are performed, whether the tests are routine, design, or by request only, and the standards which specify the requirements and test codes are shown.

Electric Motor Drives for Oil Well Walking Beam Pumps

For many years, polyphase integral horsepower motors have been the principal driving source for walking beam pumps in the oil fields. Available motor types are numerous, and all have been used, ranging from quite standard motors to highly specialized ones. Over the years, electrical and mechanical features particularly fitted for oil well pumping service have evolved, and most present day beam pumping motors incorporate these features. Nevertheless, for various reasons, many motors are still applied without all the features of the most common version of the oil well pumping motor, or with even more specialized features. This paper will compare ``standard'' motors, the ``most common'' category and the ``highly specialized'' ones with respect to oil well pumping service.

THYRISTOR CONTROLLED PULSATING FIELD RELUCTANCE MOTOR SYSTEM

ABSTRACT Integral horsepower pulsating field reluctance motors are treated when operating in dc-supplied, fixed voltage, thyristor controlled variable speed systems. A thyristor controller with two operating modes is described. Exciting MMF differential equations are put into normalized forms, simplifying their solutions, which are given. Three parameters Q, p and xrs concisely character= rize motor, MMF differential equations and torque. For typical speed/torque curves thyristor control angles are determined. Optimum pole- and gap dimensions are investigated on the basis of published permeance charts.

A DC-Type Hybrid Step Motor for Large Power Applications

The design, construction, and operation of experimental models of a dc-type hybrid step motor are discussed. This form of hybrid motor consists of a variable-reluctance step motor, the rotor of which is appropriately wound as a multipole dc motor. A computer-aided design procedure is discussed that is used to obtain the optimum parameters of the dc portion of the hybrid motor. The results obtained with two experimental models of this type of hybrid motor are presented. Both prototypes show a marked improvement in the running torque characteristics due to the dc windings. Torque-speed curves indicate load torques of 400 oz-in available at speeds up to several thousand revolutions per minute with one of the proto-types. This type of hybrid motor may be controlled in one of three different ways: a pure step motor, a pure dc motor, or a dc-aided step motor. The relative advantages, disadvantages, and application of each control mode are discussed. Several control strategies-open and closed loop-are presented for speed control as well as point-to-point type control of position. The practical feedback feasibility of this concept for high-power applications in the integral horsepower range is discussed.

Comparison of Application Capabilities of U and T Rated Motors

The inception of the T-frame line in the mid 1960's as the new standard integral horsepower induction motor has frequently raised the question among users as to the relative application capability of these motors to previous U-frame motors with which users have good application familiarity. This question has been asked and answered in numerous technical presentations and conferences. The aspects of the topic that have aroused most interest are: 1) insulation systems, temperature rating standards, and relative insulation life expectancy, 2) effect of overloads, 3) effect of over- and undervoltage, 4) effect of unbalanced voltage, and 5) bearing and shaft sizes.

Application of Inherent Thermal Protection to Industrial Motor Systems

The operation of integral horsepower motors in typical industrial applications presents unique problems requiring protective functions which go beyond those available with conventional systems. Because machine downtime results in one of the industry's most perplexing economic problems, it has become imperative that fault conditions be identified on a continuing basis. An expandable electronic system is described which not only provides protection for the motor and driven equipment but also allows the maximum safe utilization of the motor's overload capability. The compatibility of this system with the National Electrical Code requirements is also discussed.

Optimization Of Pplyphase Induction Motor Design: A Nonlinear Programming Approach

The problem of optimization of induction motor design is tackled as a nonlinear programming problem. The objective function or the cost function is formed taking only the material cost into account. The specifications like pull out torque, starting torque etc. are put as constraint functions. These functions are expressed in terms of important dimensions of the machine which are assumed to be continuously variable. The sequential unconstrained minimization technique for nonlinear programming is used to obtain an optimum design. Analysis and synthesis programs needed for the problem have also been developed. The method is applied to a line of small single cage integral horsepower motors.

Simulation of Polyphase Induction Machines with Deep Rotor Bars

Simulations of induction machines under dynamic conditions have heretofore been based on two-phase models using constant circuit parameters. Most induction motors in the integral horsepower sizes have rotor bars of sufficient depth that they cannot be accurately represented by a constant rotor resistance under all operating conditions A method for incorporating the rotor deep-bar effect in a dynamic simulation is presented.

Discussion of "Influence of NEMA T Rerate Program on Integral Horsepower Motors for the Petroleum Industry"

Discussion of "Influence of NEMA T Rerate Program on Integral Horsepower Motors for the Petroleum Industry"

NEMA Suggested Standards for Future Design of AC Integral Horsepower Motors

This paper discusses the new NEMA suggested standards for future design of ac integral horsepower motors, 1-200 hp where the horsepower ratings have been increased for frame sizes, and compares them with the standards (T versus U frames). Design changes necessary to meet the new standards are indicated.

Progress on Development of IEEE-ASAE Rural Motor Starting Application Guide

Integral horsepower motors from 1 to 30 hp are becoming more common on fanns for large feeding, crop drying, and irrigation systems [1]. Multiple-motor loads of 20 to 65 hp or more are being operated on single-phase power [2], [3]. As large motor loads on rural systems become more numerous, the problems associated with their use need more attention.

Influence of NEMA T Rerate Program on Integral Horsepower Motors for the Petroleum Industry

Factual information is presented to show that rerate T-frame motors offer users substantially more value than motors of prior vintage. The gain is not alone a matter of size-weight reduction nor the obvious economic one of avoiding, in industrial ac motors, the inflationary price spiral that generally afflicts American manufactured products. Gains are also evident in: insulation life expectancy, bearing load capability or bearing minimum fatigue life, thermal margin in the bearing lubricant. Through improved computerized design techniques, these gains are achieved without sacrifice in motor efficiency; design level of power factor is slightly lower for T-frame motors, but in-service power factor is generally improved over previous U-frame motors because the T-frame units are designed to a more realistic voltage standard.

Temperature Differentials in Single-End Ventilated Integral Horsepower Motors [includes discussion

It has been found that glass-tube thermometers are seldom used for determining motor-winding temperatures and that thermocouples provide more accurate results and are more convenient to use. It is recommended that thermocouples be specified instead of thermometers using the present temperature limits now specified for the rise-by-resistance method.

Operation of Large D-C Motors From Controlled Rectifiers

The d-c output voltage of a typical power rectifier has more ripple than the output of a d-c generator. The ripple increases as the number of rectifier phases is decreased. It also increases as the rectifier voltage is reduced by phase retard. The voltage ripple affects the performance of d-c motors in the following respects: 1. Heating. 2. Commutation. 3. Speed regulation, particularly when current is discontinuous. D-c motors constitute the major part of the load of general purpose power rectifiers. It is a matter of experience that d-c motors in the fractional horsepower and small integral horsepower ranges must be derated when they are operated over a wide speed range from rectifiers with voltage control. The factors which result in derating of these motors are present to a very limited extent in general purpose rectifiers, which usually have six or more phases and are seldom operated with more than 15 per cent phase control. Hence little consideration has been given to the derating of motors connected to such rectifiers. In recent times the extension of controlled rectifier drives to d-c motors in the range of 100 horsepower or more has raised the question of modifying the rating of these larger motors when operated from rectifiers with phase control.

A design method for D-C machines

INTEREST in d-c machines in many phases of the war effort prompts the writers to present a method of design which has been found to be very useful and time saving. The method makes use of fundamental relationships in somewhat different forms and approaches the design from a different viewpoint than is ordinarily the case. The procedure has been in use for some time in the design of low-voltage aircraft motors and normal-voltage integral horsepower motors and generators. Comparative design and test results have shown good agreement.

A Design Method for D-C Machines

INTEREST in d-c machines in many phases of the war effort prompts the writers to present a method of design which has been found to be very useful and time saving. The method makes use of fundamental relationships in somewhat different forms and approaches the design from a different viewpoint than is ordinarily the case. The procedure has been in use for some time in the design of low-voltage aircraft motors and normal-voltage integral horsepower motors and generators. Comparative design and test results have shown good agreement.

Abridgment of line-start induction motors

Many manufacturers of polyphase squirrelcage induction motors in the integral horsepower sizes have now added to their other products, a modified form of squirrelcage motor in which the starting current is reduced below that of the standard squirrelcage motor. The reduction in starting current is sufficient to warrant the power companies throughout this country to permit the starting of these motors directly across the line without the use of a starting compensator. This type of motor is now sold under a variety of trade names, such as line-start motors, auto-start motors, double-deck motors, double squirrelcage motors, high-reactance motors, etc.