. The street railway review . b-station eipiip-meut can be taken to the crippled station and be connected readyto opeiate until the repairs have been made. The storage battery in a sub-station of this character has manyadvantages. It supplies all the sudden and excessive demandsfor current, due to the fluctuating load, peculiar to a road ofthis kind, operating few and heavy trains. The rotaiy convertercan be made to carry a fairly average load, and in turn thegenerating machinery at the power house can be operated underconstant conditions. This feature of steady load cannot fail tocontribute t
. The street railway review . b-station eipiip-meut can be taken to the crippled station and be connected readyto opeiate until the repairs have been made. The storage battery in a sub-station of this character has manyadvantages. It supplies all the sudden and excessive demandsfor current, due to the fluctuating load, peculiar to a road ofthis kind, operating few and heavy trains. The rotaiy convertercan be made to carry a fairly average load, and in turn thegenerating machinery at the power house can be operated underconstant conditions. This feature of steady load cannot fail tocontribute to the fuel economy of the generating .station. Asthe station is relieved of the necessity of supplying the occasion-al maximum load by the ability of the sub-station batteries torespond for short periods to an excessive demand, machineryof iiue-h less capacity is required in the power house than if thebatteries were not used. A correspondingly reduced investmentis required in transmission lines and rotary converters. To these. PLAN OF SUB-STATION. advantagfs may be added one more, which is peculiar to thealternating-direct current system of distribution. The effect ofthe self induction of the alternating current motors in the sub-stations compels consideration of leading and lagging cur-rents, which may become extremely troublesome. The best con-dition for operation is when the power factor of the circuit isunity; that is when the apparent energy is equal to the realenergy. The strength of the motor field can be adjusted at anygiven load so as to neutralize the inductance of the line, andleave the current nearly in phase witl) tlir r. m. f. If the motorcan operate at or near this given the power factor willnot depart far from unity, and the circuit will act like a con-tinuous current line. If the load varies, however, to any great ^1JiM%ib^v^%tor :u\:, extent, the resulting false current may compel the transmis-sion over the lines of a cvirrent greater than that really
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Keywords: ., book, bookcentury1800, bookdecade1890, booksubjectstreetrailroads
