. Electric railway gazette . generators. The synchron-ous motors in the sub-stations may be started either fromthe three-phase mains or by the commutating machines, suit-able means being provided. In the sub-stations are auto-matic circuit breakers, such as are commonly used in thepractice of the General Electric Company. Duplicate tripleconcentric cables are laid between Balls Bridge and Black-rock, so that in any emergency there will be no failure ofservice. Allowing one and one-half Board of Trade unitsper motor car with trailer per car mile, the percentage dropin the three-phase main, plus
. Electric railway gazette . generators. The synchron-ous motors in the sub-stations may be started either fromthe three-phase mains or by the commutating machines, suit-able means being provided. In the sub-stations are auto-matic circuit breakers, such as are commonly used in thepractice of the General Electric Company. Duplicate tripleconcentric cables are laid between Balls Bridge and Black-rock, so that in any emergency there will be no failure ofservice. Allowing one and one-half Board of Trade unitsper motor car with trailer per car mile, the percentage dropin the three-phase main, plus that in the trolley main, willbe less than 8 per cent. With the same weight of copperat 500 volts, the drop would amount to 30 per cent. Themaximum drop in the earth return under normal conditionsof working will not exceed two volts. The current densityin all of the underground contacts is so extremely low thatany likelihood of trouble from electrolysis is avoided. Themachinery, as well as the general installation, has been. GENERAL PLAN OF SYSTEM. and adequate supply of condensing and feed water, and thatthe present buildings are suitable for offices, shop-, and soforth, while certain further local conditions had also to bemet. By referring to the accompanying diagram it willbe seen that the Balls Bridge station is about half a milefrom the city end of the lines. In case the whole currenthad been brought over the rails for return, the drop wouldhave amounted to about 20 volts; the cross-section of eachof the four rails being seven and one-half square inches, itbecame evident that if the road was to be operated from BallsBridge several points of distribution were necessary. Thetramway company possesses suitable buildings for sub-sta-tions at Blackrock and Dalkey; it was, therefore, decidedthatthe most satisfactory way of meeting the conditions wasto operate the portions of the road sufficiently accessible tothe main station f:om ordinary railway generators, and totransmit the
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Keywords: ., bookcentury1800, bookdecade1890, bookpublishernewyo, bookyear1895
