Induction type indicating instruments

The modern switchboard, controlling as it does large amounts of power, and often situated where space is at a premium, demands a different type of switchboard instrument from that to be found on older switchboards. Moreover, modern generating equipments, generally turbine driven, have resulted in a readjustment of the comparative importance of the different kind of electrical errors to which indicating meters are subject. not example, the frequency of a modern system does not usually vary more than one or two cycles from the normal speed, and therefore frequency characteristics are less important whereas formerly this was one of the great sources of error. Again, due to operation with larger currents or higher potentials, the external magnetic or electrostatic field effects are greatly increased.