The Single-Phase Wattmeter

Author: E.E. Kimberly

The most common type of wattmeter operates on the same- general principle as does the dynamometer-type voltmeter. The fixed coil contains a few turns of large wire and is connected in series with the power circuit, just as is an ammeter. The movable coil with its series resistor is connected across that part of a circuit in which the power is to be measured. The divisions of the scale are somewhat crowded in the lowest part, and readings obtained in the lowest 10 per cent of the range should be regarded as unreliable. A wattmeter measures average power.