Nos. 7 to 12 KARL FREDRIK WINCRANTZ. Managing Director of ...

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not be alive any longer than is absolutely necessary,every group of lamps is equipped withan outdoor group switch which also lights anoutdoor lamp. By looking out into the farmyardthe owner can therefore immediately seewhether the conductors within the buildings arealive or not. All the switches appartaining to theplant ar? placed near the lamps. Thus all specialswitch conductors with the dangers theyinvolve are avoided, and simultaneously thenumber of junction boxes is reduced.The question of costs is often decisive for thechoice of installation system. The cheapestsystem is generally preferred. But even herethe old paradox applies that "he who pays dearbuys cheap". It is not the initial material costsand the installation costs that should be comparedto one another, but it is the sum of amortizationand maintenance costs that gives thereal comparative values.Figure 15 shows graphically the costs of installedconductors for three installation systems,Fig. 15. Graphical tabic indicating installation costs with different conductor systems.If in planning an installation one hesitateswhether to install a junction box or to put ina few meters more of cable it may be mentioned,by way of information, that the installation costsfor a junction box correspond to that of fivemeters of cable. Thus, if it is possible to savemore than five meters of cable it will be cheaperto install an additional junction box but in othercases not.As is obvious from figure 14 the length perlamp of the conductors is relatively small in thecase of a well planned installation. Since thereliability is always depending upon the numberof junction points and the length of the conductors,the rubber-lead conductor system offers,in this respect as well, important advantagesover older installation svstems.viz., single-core conductors on insulators fordamp places, armoured conduit system and leadcovered rubber cable installations. From thetable is seen that the difference between thecosts of installation of the conductors is rathersmall for the three systems. The rubber-leadconductor is somewhat cheaper than the singlecoreconductor but somewhat more expensivethan the armoured conduit. This is made stillclearer by figure 10 showing a table of the costsof construction for a number of installations.Compared with the single core conductor therubber-lead conductor system is cheaper throughout,but it is somewhat more expensive thanarmoured conduit installations. The table showsthat this additional cost in the two cases is 5and 9 per cent respectively. However, if we8. 215
Fig. 16. Examples of cable costs for a number of installations.compare the sums for the various systems itwill be seen that the rubber-lead conductorsystem in the cases given is cheaper by 11 percent on the average.In the case of a complete installation therubber-lead system will, on the contrary, generallybe higher in price, and the examples givenin figure 17 show an average additional cost of22 per cent. This additional cost falls entirelyon the fittings. The fittings are constructed tocomply with requirements quite other and morerigorous than does the ordinary installation material.and their price must therefore be higher.In order to reply to the question whether it willpay to install this more expensive material it isnecessary to know the relative life-time of thevarious systems. Unfortunately it is not yetpossible to answer to this question in full, hutexperience has furnished certain figures whichmay be guiding. In the case, for instance, of avery complicated installation where the singlecoreconductor system had to be replaced everythree months the rubber-lead conductor installationwas still after six years in a satisfactoryshape. The construction of the system excludesany condensation whatever in the conductingcables and if it should occur in the fittings theyought to have been exceptionally badly mounted.The fact that all live parts are hermeticallyFig. 17. Total installation costs for installations indicated in figure IS.enclosed in a carefully grounded metal coveringalmost excludes leakage. The result of all thisis that the rubber-lead conductor installationsare the least dangerous and the most fire-proofof all the systems. The electrical strength andthe high insulation of this system place it in aspecial class. For an installation with leadcovered ruhber cable it is stipulated a minimuminsulation of 5 megohms, or more than 22 timesas high as that prescribed for armoured conduitinstallations. To this comes that there are nodifficulties whatever to reach this value, and asa rule the insulation is many times higher.In addition the rubber-lead conductor systemhas been throughout worked out with a view toneutralize chemical action. As has been mentionedabove this purpose has also been fulfilled.This installation system is the only one whichit is allowed to use in damp places where thereis at the same time a risk of fire. According tothe actual prescriptions it can and may be installedin any place where electrical installationis at all allowed. It makes possible unificationand standardization of installation technics, oneinstallation system for all kinds of places.In order to make it possible for owners ofelectric plants to have their installations modernizedwithout undue loss of time, a close collaborationof all parties busy in the sphere of instal-216 -
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VOL. 7 1930Nos. 7 to 12KARL FREDRIK
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The Svenska Radioaktiebolaget Audio
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the condenser C and the coil L. The
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showing a continuous large increase
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The Hallsberg Electric Interlocking
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with groups of express trainsbetwee
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R 1724 Fig. 5.The new L. M. Ericsso
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signal levers that must be moved fo
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terminals A and B. 5, and S,' are t
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X is the distance to the point refe
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Through W r . — W llt (equation 7
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) line 2:where a is the wave-length
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or also:I. e.: If the inducing line
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φ is the angular velocity and y, r
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coupling may b2 distributed along t
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Fig. 2. An Automatic Fire Alarm Sta
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Fig. 7. Thermo.-contact filled in W
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R 1591Fig. 16. Fire Station Apparat
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Fig. 20 a. "Svenska Tcatern" lire i
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A further demonstration of the risk
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New Interlocking and Signalling Pla
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is effected automatically by the tr
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the old plant, with its three inter
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Fig. 2.Fig. 1.Sonic drawbacks or di
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The characteristic impedance Z. of
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Fig. 4.is taken from this paper, an
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Fig. 5.If we measure the impedance
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geneity can be calculated from the
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with any greater accuracy than one
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n is, however, a scalar magnitude f
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that ZL is almost equal to Z B and
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Fig. 15.Fig. 16.160
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The air core transformer can, there
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Fig. 1.Fig. 2. Fig. 3.
Page 72 and 73: F 1584 Fig. 4. Interlocking Machine
Page 74 and 75: Porcelain Insulators and Insulator
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Page 78 and 79: R 1751 Fig. 3. Above, Distribution
Page 80 and 81: always had a relatively short life,
Page 82 and 83: Fig. 1.When the D. C. voltages and
Page 84 and 85: orIf the resistance H 0 of the pote
Page 86 and 87: valve not being the same as the ano
Page 88 and 89: -10Fig. 9.sistance W, of a valve, t
Page 90 and 91: non-linear distortion, the magnitud
Page 92 and 93: On the Calculation of Delays in an
Page 94 and 95: By the use of the previously deduce
Page 96 and 97: We, therefore, make an extremely sl
Page 98 and 99: generally thusExample: We supposel
Page 100 and 101: Fig. 2. Delays at free selection of
Page 108 and 109: Working Reliability and Maintenance
Page 110 and 111: TABLEII.The results of the control
Page 112 and 113: Lead Covered Rubber Cable Installat
Page 114 and 115: Husum sulphate mill, hall of paper
Page 116 and 117: ed lead impregnated cable is not re
Page 118 and 119: Fig. 7. Connecting cover for pendan
Page 120 and 121: Fig. 12. Junction box for switch.wa
Page 124 and 125: lation technics is required. Above
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Nos. 7 to 12 KARL FREDRIK WINCRANTZ. Managing Director of ...

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