Cyril G. Veinott

Performance Calculations on Induction Motors Practical Straightforward Means for Calculating Performance of Single-Phase or Polyphase Induction Motors

Practical means for calculating the performance of both single-phase and polyphase induction motors from previously determined constants are developed in a straightforward manner. The methods are suitable for accurate calculations but can be simplified for approximate calculations. The methods given are complete and no auxiliary charts or sets of curves are required, nor need any diagram be constructed. The single-phase calculation method is based on the cross field theory presented by H. R. West. The polyphase calculation method is based on the equivalent circuit.

Performance calculations on induction motors

The MEANS given in this paper for calculating the performance of both single phase and polyphase induction motors is intended primarily for calculations from previously determined design constants. By actual trial the methods have been found to be very easy to learn and use even without a knowledge of induction motor theory, and are very rapid.

Effect of Altitude on Electric Breakdown and Flashover of Aircraft Insulation

ELECTRIC power to operate auxiliaries is now an indispensable requirement of modern aircraft. Within the past ten years the electric load on an airplane has increased more than tenfold.1 The optimum voltage for electric systems for large aircraft already has more than exceeded the present 24-volt standard,2,3 and the use of higher-voltage systems, already tried experimentally,4 now appears to be a certainty. Moreover, the operating altitudes of modern airplanes, particularly military craft, are climbing steadily to ever increasing heights. Each of these factors indicates a need for a careful study of the requirements for insulation of aircraft electric apparatus in order to achieve minimum weight and space without sacrifice of reliability. A preliminary study of this subject was made and reported5 prior to the use of the 120-volt a-c system on the XB-19, but the projected use of 208-volt systems4 for still higher altitudes makes a more comprehensive study of this problem most timely.

Starting Windings for Single-Phase Induction Motors

Methods are given to enable the design engineer to determine the best starting winding and the best capacitor, reactor, or resistor required to meet any specified requirements. The methods given have been in actual use by design engineers for over 12 years, and are as useful today as they were when developed. Simple circle diagrams depict graphically the principles involved in the method. Some practical observations, based on experience, are given. A calculation form, with sample calculations, is also included.

Irregular Windings in Wound Rotor Induction Motors

The importance of using regular windings in polyphase wound rotor induction motors is stressed in this paper. Harmful effects upon the efficiency, power factor, breakdown torque, and noise of the motor may result with an irregular winding, due to differential leakage. The Goerges diagram of tooth fluxes is presented for studying this phenomenon. Means of avoiding trouble of this sort also are pointed out. It is further observed that 3-phase motors having a number of poles which is a multiple of 6 are most likely to be troublesome.

A 40-Kva 400-Cycle Aircraft Alternator

A-c auxiliary-power systems for aircraft date back to World War I. Recently numerous technical articles have indicated an intense revival of interest in this subject. Heart of any electric system is the generator which supplies electric power to all parts of the system. An alternator, especially designed and built for 208-volt three-phase systems is described in this paper. Light weight and reliability dominate the design, which involved a large number of new and unusual problems.

Moneca — A new network calculator for motor performance calculations

Performance calculations on single-phase induction motors require two to four times as long as comparable calculations on polyphase motors. A new calculator based upon a new revolving-field equivalent circuit has shortened the time for making these calculations and has made practicable many calculations which were formerly too time-consuming.

Some problems in the standardization of temperature ratings of fractional-horsepower motors

AT the winter convention of the AIEE in New York in January 1939, there, were presented a number of papers on temperature rating of electrical apparatus.1–6 Since that time AIEE Standards No. 1 has been tentatively revised to favor the resistance method for determining the temperature rise and changing the limits for this method from 55 degrees to 60 degrees centigrade. Little data have been published on how the proposed changes in standardization might affect fractional-horsepower motors. For this reason the study out-lined in this paper was undertaken. It is hoped that the information given herein will be of some assistance in standardization problems affecting fractional-horsepower motors. It is further hoped that others who have similar data on fractional-horsepower motors will make them available, regardless of whether they may support or differ with the data in the paper, in order that correct information representative of the industry may be available to those who make the standards, or any future revision of them.

Blast-Tube Cooling for Aircraft Generators

Established principles of hydraulics are used to develop and explain fundamentals of blast-tube cooling. It is shown that the pressure-volume curves of a blast tube can be determined by flight tests, and that the pressure-volume curve of a generator can be determined in the laboratory. From the two pressure-volume curves, the air-flow through the generator in flight can be predicted, without an actual flight test on the generator. This procedure would save many flight tests, if pressure-volume curves of various blast tubes were available. It is shown that the pressure-volume curve of a blast tube can be determined by open-end and closed-end readings on the blast tube, and the complete curve can be expressed in terms of two constants readily determined from these readings. Once values of the constants are established, air-flow calculations become as simple as the application of Ohms law. The theory also covers generators with an internal fan. A plea is made for accurate blast-tube data and for better specifications on blast cooling. A suggested form of blast-tube specification is given.

Measurement of Noise From Small Motors

An analysis and summary of some of the concrete problems and considerations involved in the measurement of noise caused by fractional horse power motors are presented in this paper. Some experimental data and several important conclusions are given, but much remains to be done befoe standardization is possible. Desirable characteristics of a noise meter for this application tion are pointed out.