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Volume 43, Issue 420
Displaying 1-8 of 8 articles from this issue
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S. OSHIDA1923 Volume 43 Issue 420 Pages 587-616
Published: 1923
Released on J-STAGE: November 20, 2008
JOURNAL FREE ACCESS -
J. T. TAKEUCHI1923 Volume 43 Issue 420 Pages 617-637
Published: 1923
Released on J-STAGE: November 20, 2008
JOURNAL FREE ACCESSUp to this time, in Japan, we customarily adopted double rating which estimate the capacity of machines by two different temperature rises of two different load. ie at full load and at over load, or we first decide them at full load and again at over load of certain duration of time, say one hour or two hours or even more. Such a method of rating is only to estimate machines not precisely but also make the matter too complicated.
In 1913, therefere, Berlin international commission, of the ratings decided to adopt single rating which estimate machines by the final temperature rise at full load only. This decision of the single rating was also approved by our Japanese Commitee.
Immediately after this time, the world's great war broken off the commission.But, in 1919, the London International Cammission discussed about the matters of rating and once again decided to adopt the single rating. Such in Japan aur committee discussed also about the matters of rating, in Tokyo. Kansai, and in Kyushu, but they find no reason to change the previous international decision and adopted single rating for the estimation of all electrical, machinary.
As, however still, there are many who do not well understand the real meaning of single rating, the author intended the investigation of the temperature rise electrical machine and the comparison between double and single ratings and also their relation to the distribution of losses. These copper and iron losses have different effect to temperature rise of the machine, because the copper loss will be produced in the windings which is fully enclosd by insulators of nonconducting materials of heat, while the iron loss will be produced in the iron core which is directly exposed to the cooling air. Therefore we can not treat these both losses as sum in total but must consider their relations one from the other.
The author solvod this problem by simultaneous differential equation which takes the said consideration in the relation between the losses and cooling effects and also in in the heat commnunication between windings and core, ie one of these equations based on the copper loss and the other on the iron loss and these two equation simultaneously interconnected by the heat communication between the two losses.
He discussed also the retation between efficiency and temperature rise, thus arrived at the result which tell us, that the efficiency of the same machine do not depend upon the temperature rise by which the machine should be rated, if the ratio of the both loss remain the same (of cause there neglected that the increase of losses due to the temperature rising).
Also, he find very simple new method, by which we can calculate easy the relation between temperature rise and capacity according to the ratio of both losses.
Finally, he gives few experimental results, by which we can see how the said theories will go, and discussed on the comparison between double and single ratings. It proves the single rating is very much more preferable than double rating in all points.View full abstractDownload PDF (1033K) -
YASUSI WATANABE1923 Volume 43 Issue 420 Pages 638-652
Published: 1923
Released on J-STAGE: November 20, 2008
JOURNAL FREE ACCESSThe so-called ferro-resonance, or the resonance in a circuit including a condenser and an iron-core inductance, remains as one of the most important problems with regard to Peterson's earthing coil.
In this report, the writer describes the results of experimental studies on the following topics:
a. The effect of resistance on the ferro-resonance.
b. Characteristic curves of jumping points, as dependent on the circuit constants.
c. Jumping phenomena caused by the variation of resistance under constant impressed voltage.
d. Observations of the jumping phenomena by means of the Braun tube oscillograph.
Expressing the relation between the square of the impressed voltage and the square of the current by an algebraic equation of the 3rd degree, the writer explains certain phenomena with regard to the jumping of the resonance current.
He also shows a new method of graphically representing the jumping phenomena.
This paper is divided into the following sections:
I. Remarks on the mathematical methods of explaining the ferro-resonance.
II. General equation relating to the jumping phenomena.
III. Graphical method of esplaining the jumping phenomena.
IV. Experimental results obtained with regard to the four topics above mentioned.
V. Conclusions.View full abstractDownload PDF (817K) -
YASUSL WATANABE1923 Volume 43 Issue 420 Pages 653-660
Published: 1923
Released on J-STAGE: November 20, 2008
JOURNAL FREE ACCESSThe author proposes a new method of grounding the neutral of a tran- smission system, namely the use of a condenser in conjunclion with a grounding reactor.
"The grounding LC reactor", as the author suggests to call it, is either of the following.
(a) An iron-core inductance coil with a condenser connected in parallel.
(b) An iron-core coil put in series with a resistance, and then connected in parallel with a condenser.
The advantage of the LC reactor lies in the fact that, a reactor with a slightly saturated core may be safely employed so as to exactly compensate for the capacity current, without causing any appreciable wave distortior, so that the quenching action is ideally effective.
The danger of the so-called series resonance, which is the most serious drawback of Peteren's resonance coil, may be avoided by the use of the LC reactor, for the combination behaves with regard to the series resonance just like a single reactance coil with highly saturated core and a high series resistance.
The underlying principle of this new form of grounding reactor is explained by graphical methods, and some experimental results are described relating to the LC reactor.View full abstractDownload PDF (464K) -
SHINJI TOGO1923 Volume 43 Issue 420 Pages 661-668
Published: 1923
Released on J-STAGE: November 20, 2008
JOURNAL FREE ACCESS§. I. Equilibrium points in resonance.
Corresponding to a given E. M. F. and a given capacity, a resonance curve or a curve of current for varying inductance may be plotted. On the other hand, the variation of inductance of an iron cored reactor with varying magnetizing current may be represented by a sabstitution curve. The equilibrium conditions can be found out as the intersecting points of these two curves.
§. II. Elementary reactor.
For the study and design of a resonance reactor, it is convenient to consider an elementary reactor, i. e. a reactor with uni volume of iron core and a single turn of winding around it.
§. III. Protection against series resonance.
In order to protect against the danger of the so-called series resonance, it is advisable to design a reactor for a high flux density, and the use of a certain amount of series resistance will also be advantageous.
§. IV. Conclusion.View full abstractDownload PDF (427K) -
H. YAGI1923 Volume 43 Issue 420 Pages 669-676
Published: 1923
Released on J-STAGE: November 20, 2008
JOURNAL FREE ACCESSDownload PDF (599K) -
Y. TORIYAMA1923 Volume 43 Issue 420 Pages 677-693
Published: 1923
Released on J-STAGE: November 20, 2008
JOURNAL FREE ACCESSWe studied the absorption of moisture by Various fibrous insulating materials. At first, the sample is dried for several days by placing it in a hygrostat containing concentrated diluted sulphuric acid, and its weight is measured; then the acid is step by step up to the relative humidity 95%. The relation between the absorption of moisture and relative humidity is expressed in the following formula which is concordant with observed values for a range of zero to 95 Percent by relative humidity.
Q=1/a/H+b-cH.
where Q=moisture absorbed in percentage.
H=relative humidity in percentage.
a.b.c=constants depending upon insulating materials.
The absorption of moisture by fibrous insulating Materials depends on the mode of variation of humidity. A considerable difference is observed in the quantity of moisture absorbed, whether the humidity varies from dry to wet or wet to dry. That is, there are hysteresis phenomena in the absorption of moisture by fibrous materials. All of the above experiments are conducted in a thermostat of constant temperature of 30°C.
In order to ascertain the effect of temperature rise on the absorption of moisture, the concentration of the sulphuric acid in the vessel being maintained constantly and the temperatere of the surrounding of the vessel being varied, the change of weight of the sample is observed. The weight of the sample does not change so much, but it decreases very little with temperature rise.
Lastly, by utilizing toe phenomena of temperature rise of a sample caused by the absorption of moisture, we compared the absorption of moisture by various samples in vacuum. This method does not give accurate absolute value of the absorption of moisture, but it is convenient to compare many samples in a short time.View full abstractDownload PDF (955K) -
S. JIMBO1923 Volume 43 Issue 420 Pages 694-700
Published: 1923
Released on J-STAGE: November 20, 2008
JOURNAL FREE ACCESSThe author has shown that a general equation of the representative a. c. bridge which would comprise more various actual bridges as special cases than the one treated by prof. Katapetoff can be readily derived by the use of algebraic methods, appling the gene al theory of a. d. c. network.
The three available equations derived from the general oquatiou have been described with some practical applications.View full abstractDownload PDF (280K)
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