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OCR for page 101
II1SItLL-T ~ PAPER
W. McMahon
Bell Telephone Laboratories, Inc.
Murray Hi 11 , New Jer ~ ey
Canacitore
Capacitors _ Their Use in Electronic Circuits] - M.
Brotherton. This emalLl (104 ~age) volume contains a description
of the electrical, physical and chemical properties of imp~egnat;ed
Cater ce~nacitors as spell as their various applications in electronto
circuite. Besides this most of the Rena jor improvements in the manu-
facture of ca~aci\Q~ in recent years are described briefly.
Capacitor Life Teating2 _ J. R. Weeks. Equipment and
techniques he described for making accelerated teats of capacttore
largely of the impregnated parer type. In tests which are acceder
rated by employing DC droll age higher than that to which the capact-
t~ors will be subjected in service the fifth power rule is used to
estimate the probable life of the test units. Men elevated tem-
nera~Gure ts the accelerating agent, it is found that the life of
impregnated caner capacitors is approximately halved by each 10°Ce
increase in temperature.
Dielectric Proper _
Studs es of Dielectric Properties of Chemical Pulps3 -
Cyril Delevanti, cr., and P. Be Ragmen. The authors have devised
apparatus axed developed a technique for measuri ng; the dielectric
constant and dielectric loas of paper sheets. Data on these pro_
er~ciea There obtained, using a pulp of known`; chemical corapositior~.
Their findings indicate that es the quantity of abe orbed metallic
ions increases the ~ one - factor increases; especially at higher
frequencies and that dielectric constant is slightly increased bar
increasing metal ion content. Lignin in paper appears go contr1-
b '.te largely to its loas factor. On the other hand, lignin due to
its chemical nature Probably effectively ties up appreciable quan-
titie~ of ions occurring in dielectric impregnants. This augges~Ge
that unbleached pulp may be best sulted for DO anplicatione whereas
bleached fibers may be more satisfactory for AC applications. The
experimental re su] ts were all obtained on uni~regna4Ged paper and
the authors make no predictions of applicability to impregnated
caner combinations.
Studies of Dielectric Propertles of Chemical Pulpa4 -
D. O. Adams. The dielectric strength of unimp~egnatea cab] e
paver was measured under various conditions. All samples were
tested in an atmosphere of nitrogen. The effects of gee Pressure,
relative humidity, ternpera~Gure, sheet density and sheet thickness
were studied. It was found that the dielectric breakdown gradient
_ 101
OCR for page 102
increased &9 gee pressure increased but decreased with lncreasl~
relative humidity, temperature, sheet Penalty and sheet thickness.
The effect of gas pressure appeared to be most Pronounced. A
theory is offered to explain the. behavior of the paper under these
various conditions. The author concludes that the breakdown
gradient of a sheet of paper in a gas 18 not a measure of the ln-
trinelc dielectric strength of either the paper or the gas. Rather
it is a complex phenomenon involving the dielectric strength of
both. Moreover, in view of his theory, the author feels that it
is difficult, if not i~oasible, to translate the breathe own per_
romance o' ur~impregnated paper in the gas to that of oil or resin
impregnated paper. He suggests that, while the lack 02- correlation
between the dielectric strength of nape r as tested in air and its
performance in service is frequently attributed to variations in
impregnation, the true cause may lie in the fact that the mechanism
of breakdown i n air is quite different from thug in oil.
Some Properties of Insulation made from Ceroa Fibers -
R. C. Should. Mr. Sproull has investigated the comparative re-
activity of Caroa paper and Manila paper when aged at 1250C. in
the presence of chlorinated diphenyl. Re concludes that the f ormer
is at ~ east as stable as the latter and both are satisfac~Gory for
use in insulation impregnated with chlorinated aiphenyl. As for
electrical characteristics, the power factors of the two papers are
practically identical up to 80° Then compared on the game density
basis. From 80e to 100 ° the power factor of Manila pacer increases
more rabidly than that f or Caroa. The dielectric strength measure_
meets of the two ne.~ere' which were made Edith various coil struc_
tureo and ale o paired 'sires, indicate that Caroa is the equal of
Man' la paper.
.
~52
Paner Ca~acitor~ Containing Chlorinated Imp~egnants6 -
L. Egerton and D. A. McLean. This paner i8 one bt a groun on
the mechanism of stabilization of chlorinated impregnants in paper
canacito-e under electrical stress. The authors had previously
.. .
established the fact that the edition of small amounts of certain
organic coonhounds, notably quinones and nitroaroma&cics, to chiori-
nated diphenyl or chlorinated naph~Ghalene considerably enhanced
the life of aluminum foil paper condensers impregnated with them.
On the hypothesis that hydrogen chloride, Split out of the im-
~regnant, sets off a chain of reactions which ultimately destroys
the dielectric, the authors have inves~Gigated the effect of these
organic additives in impregnants satura~Ged with hydrogen chloride.
Tt Auras found that the conductivity of the EC1 ~ olution, which was
quite constant ~ was not altered by the addition of the se ste.bi~ ~ zing
comnoancis. However ~ when aluminum foil was added to the impregnants
.~.
saturated Edith HC1 their conductivity increased rapidly after a
brief induction period and the aluminum was consumed. Adding
stabilizers to this System Ore vented corrosion of the aluminum and
hence conductivity sea not increase. The authors conclude that
these compounds stabil Size impregnated condensers by forming a
- 102 _
OCR for page 103
protective file on the aluminum foil. They feel it is signi-
fice.nt thet Al stabilizers discovered thus far are oxidizing
agents to some degree arid they theory ze that either an oxide or
organic metals ic tiles is formed on the metal which prevents
corrosion.
Paper Capacitors Containing Chlorinated Im~regnants _
Effects of Sulphur - D. A. McLean, L. Egerton and C. C. HOutze
This paper deals with another chase of the we on stabilization
of paper caT,acitor~ containing chlorinated impregnants. A com-
crehensive study is recounted or the eff ects of the element Bull
chum in cavort made of linen pacer and of Eraft paper with
electrodes of either tin or aluminum acrid impregnated **pith either
chat orine.ted nanhthalene or ch] orinated diphenyl. A appall amount
of Arthur adcled to the dielectric ~mpre~ant yielded a marked
extension to the life of capacitors tested at high temperatures.
Moreover, the capacitors had a lower and more stable power factor;
an effect Rich was more pronounced with tin electrodes than with
aluminum. The authors believe that the manner in which slur
nerttorme this feat is through formation of a protecting film or,
the surface of the electrode. Electron diffraction patterns of
the surface of tin electrodes used in these e~ertrnents revealed
e. layer of tin aulphide on the surfac e which supports the c on
clued or`.
Belf'_Healing Capacitors - Fred E. Henderson. This is
an abstract of Mr. Rendereon's report on "Manufacture of Metal_
lined Paper Fixed Ca~acltor Units by The Robert Boach company,
Stuttgart, Germany This process comprises lacquering one aide
of. condenser paper and then condensing a very thin film of zinc
on the lacquered surface to form an electrode. The lat~Ger step
~ ~ carried out in a thoroughly evacuated chamber in which the
Darer is massed over ~ pot of molters zinc. Condensers made Erich
. . .
metallized paper are more compact than the conventional foil type,
i.e. their ratio of capacity to physical volume is higher. Bealdes
this, they do not fall in the same manner as the f oil type cons
densers. Then e. short circuit occurs the very thin zinc film
behaves like a fuse and the metal Nburns away" from the point of
short circuit, thus opening it. Because of this, capacitors of
this type are termed "~eIf-healing". Some data are given on
manufacturing requirements and procedures
Bosch Process _ Metallized Paper9. The Bosch process
for metallizing paper for car~acitor~ is described. This article
contains a number of photographs of the German equipment which
was shipped to this country and Bet up and operated in the Western
Electric Company experimental shop in Chicago.
Metallized Paper Capacitorel° - S. J. Borgare arid others.
A British intelligence team headed by Lt. Borgars compiled this
report on the process for making metallized Caper capacitors
_ 103 ~
OCR for page 104
developed by the Germans. Part ~ of the report contains infor_
mation on the ~re~eratlon of paper for this process as T>ractiaed
by the Germans ~ The manufe~c Cure of capacitors with this
tO deseribea tn P=t II.
_ 104
.
OCR for page 105
BIBLIOGRAPHY
14 0, Van Nostrand Co., New York City (1946)
2. Bel:L Laboratories Records 24, No. 8, 296, Aught (1946)
3. Paner Trade J.,
I, NOe 25, 35, December 27 (1945)
4. Pager Trade J. ~ 122,, No. 79 43-52 (T.S. 63-72) Feb. 14 (1946)
5. Paper Trade J. 91 123, 142' October lO (1946)
6 ~ Ind. Eng. Chem., 3~3,
512, May ~ 1946 ~
7. Ind. Eng. Chem. ,, AS,, lllO, November (1946)
S. Product Erg. 17, ll7-~3, September (1946)
9. Chem. and Eng. Nears, At, 3356, December 25 (1946)
10. PB 39361 _ }Hobart Publ. Co., Box 4127, Cheery Chase Stetion,
'Washington 15 , D. C., Nov. 1 (1~46 )
_ 105 -
Representative terms from entire chapter:
power factor
