A New Application of Transient Recorder to Magnetic Measurements (Part I: Core Loss Measurement at Very Low Frequencies)

A new method have been developed based upon analogue-to-digital conversion techniques and memories. The method involves the scaling of operating frequency from "real" to "optimum" for the power loss measurement. The advantages of using this techniques are as follows: (1) extreme availability at lower frequency region, (2) high accuracy and high stability, (3) simple measuring procedure, (4) digital indication. This method can be measured the power losses over the frequency range 0.1Hz to 1kHz for magnetic circuit and d.c. to 1kHz in such a purely resistive circuit. We estimate the accuracy of this core loss measuring system within 1.0% over all these frequency range. Using this system, specific core losses of the various grades of silicon iron have been measured in the frequency range 0.1Hz to 200Hz

Iron Losses of Silicon Steel due to Rotating Fluxes (Inclined Rotating Flux and Distorted One)

Characteristics of iron losses in silicon steel due to inclined rotating fluxes and distorted ones are described. Iron losses due to rotating fluxes have been measured at various conditions for grain-oriented and non-oriented silicon steels by using an improved thermistor-bridge method. Loss measurements indicate that the iron loss due to the inclined rotating flux is greater than that due to the non-inclined one. However, the iron loss due to the distorted rotating flux is not always greater than that due to the non-distorted one

Analysis on Magnetic Characteristics of Three-Phase Core-Type Transformers (Part I: Fundamental Equations and Linear Solutions)

In this paper, we report the procedure to analyse magnetic circuits and give the linear solutions on magnetic characteristics of the three-phase core-type transformer which is composed of the complicated magnetic paths. First, we explain the construction of cores investigated and normalize the sizes of a core. To analyse these magnetic circuits, we introduced the electrical eqcuivalent circuits and obtained the general fundamental equations for each core. Then, we drew the linear-numerical solutions using an electronic computer, and cleared the relationships between the sizes of a core and the amplitudes and phase angles of fluxes in magnetic paths. Related with the above facts, we investigate the influence of these sizes on the core loss using cores of various quality

Convenient Design-Method of Pressure Tank Used for Oil-Immersed Transformer

In this paper, the easy design-method of trasformer tank is described. Using nomographs induced here, the bending moments on the oval tank or round cornered rectangular tank which is used for usual transformer, are briefly calculated. And the relation between the type of transformer and the distribution of bending moment is cleared. Using these results, even electric engineer who has poor knowledge for strength of materials, can easily design a most suitable tank

A New Representation of Distorted Wave Forms

A new method for representing distorted wave forms is investigated. The method suggested by us is a modified vector symbolic method. It has been hitherto thought that the vector symbolic method cannot be applied to the distorted waves, because the rotating speeds of each harmonic vector are not identical. Representing the argument of the n-th harmonic vector by l/n times as large as the phase angle of the harmonic component, the relative positions of respective harmonic vectors are invariable wherever the standard vector is put, and the wave shape can be deduced from the vector diagram. We found various correspondences between the wave forms and the vector diagrams. Therefore, the wave shape can be estimated from the vector diagram, and the mutual relationships between two wave forms can also be known. In electric or magnetic circuits, the causes of distorted wave forms are in general obvious. Therefore, there are very often the fixed relationships between the amplitudes and phase angles of the harmonics. Further, in polyphase a.c. circuits, there are often the fixed relationships between corresponding harmonics in the wave forms of the respective phases. When the wave forms of those circuits are discussed, the new method investigated in this paper may offer a useful key

Contactless Vectormeter Using Thyristors

In order to measure the iron loss of the silicon steel plates, we produced a vectormeter using a thyristor and a gate turn off thyristor by way of experiment. This equipment is very useful, because the frequency range is improved very much in comparison with the vectormeter which is composed of the mechanical rectifying system using a synchronous motor, namely, is enlarged from 60Hz to 1kHz

Experimental Studies of Various Factors Affecting Minor Loop Hysteresis Loss

When the distorted flux is induced in a magnetic circuit, the minor loops arise sometimes inside the major hysteresis loop. The area, accordingly the hysteresis loss of the minor loop,is affected by its amplitude and position, by the maximum flux density, by the quality of material, etc.. In this paper, we describe the experimental studies of the factors on the minor loop hysteresis loss. A method of getting the displacement factor of a minor loop which is placed at arbitrary position and has any amplitude is developed from our experimental results. Using this method, the core losses caused by the distorted flux can be calcuLated within the error less than three percent, even if the amplitude of the minor loop becomes near to the amplitude of the major loop

Analysis on Magnetic Characteristics of Three-Phase Core-Type Transformers [Part II: Non-Linear Solutions and Experimental Results for R3-Type Core]

This paper deals with the magnetic characteristics (the flux distributions, core losses, etc.) of threephase core-type transformers with double-layer. In the preceding report, only linear solutions have been given. In this paper, also non-linear solutions are discussed. Therefore, the flux waves of each magnetic path are distorted and contain various harmonics. When core losses are calculated, the hysteresis losses of minor loops are taken account. The results of analysis are compared with those of experiments. It is concluded that the principal cause for increasing core losses of this type core is the eddy current loss produced by harmonic fluxes. The flux distributions and the core losses depend on the shapes of the magnetization curve and the core-loss curve, that is, on the quality of the materials

Calculation of Circuit Constants for Impulse Voltage Generator by Means of Computer

In this paper, we describe the way to compute circuit constants of the impulse voltage generator by means of the digital computer, when an impulse voltage waveform is given. The definition of waveform is to be revised, and this definition is adopted to our computation. From the results, we can see the influence of revising definition upon circuit constants. We also devised graphs, from which we can easily determine the L-C-R circuit constants. (see Fig.2(a)