. Journal of electricity, power, and gas . ing on no load. or adjustment, which can be easily made, they may beused with accuracy on 60 cycle circuits. This is onaccount of the fact that 60 cycles is the standard light-ing and power frequency, and as the majority of thehigher frequency plants will sooner or later be changedover to 60 cycles, it will evidently be a great savingto them if they can use their old meters rather thanhave to purchase new 60 cycle meters when such achange may be made. Meters so constructed areknown as double lagged meters, since they arelagged at the factory for two d
. Journal of electricity, power, and gas . ing on no load. or adjustment, which can be easily made, they may beused with accuracy on 60 cycle circuits. This is onaccount of the fact that 60 cycles is the standard light-ing and power frequency, and as the majority of thehigher frequency plants will sooner or later be changedover to 60 cycles, it will evidently be a great savingto them if they can use their old meters rather thanhave to purchase new 60 cycle meters when such achange may be made. Meters so constructed areknown as double lagged meters, since they arelagged at the factory for two different frequencies. The effect of a frequency other than normal can bebest shown by reference to the diagram shown in , in which OE=the impressed , OI=current in potential coil at normal fre(|uency, ()Ii=current in potential coil at low frequency, Ol5=current in potential coil at high frequency, 234 JOURNAL OF ELECTRICITY, POWER AND GAS Oil,, OI,..i and Oil,.) ^ the cunents in the laggingcoil for these different Now suppose that the meter is properly laggedfor a frequency, f, the current in the potential windingbeing OI, and the flux therefrom being 0. The cur-rent in the lagging coil will be 01^, and the flux there-from will be O-^l; these two fluxes, 0 anc Otl^i. com-bine to produce the resultant flux 0<^R. which is exactly90 degrees behind the impressed Now supposethat the meter is used on a frequency, fi, which is belownormal. With a lower frequency the flux set up by thepotential coil will be greater, as the rate of change offlux must remain the same. The magnetizing , will therefore be greater, the core loss and the RVlosses will be higher, so that there will be a largerenergy component of the current, and it will thereforenot lag by as great an angle as with normal frequency ;the current 01. sets up the flux 0</)., which representsthe condition for a frequency below normal. The flux,O^i, combining with the flux 0<^l-
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Keywords: ., bookcentury1800, bookdecade1890, bookidjo, booksubjectelectricity
