exp%2047 wk5 - Experiment 47 Three-Phase Power Measurement...

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Experiment 4 7 Three-Phase Power Measurement To measure power in a three-phase circuit using the two wattmeter method. To determine the active and reactive power, and the power factor of a three- phase system. DISCUSSION A wattmeter, used for measuring power, isan electrodynamometer type instrument. This meter usually has two coils, one fixed, the other capable of turning in the magnetic field of the first. The fPced coil is connected in series with the line so as to cany the line current. The movable coil, which is of high resistance, is connected across the load (that portion of the circuit in which the power is to be measured). The small current in the coil is, therefore, proportional to the voltage between these terminals. Thb coil turns against a helical spring, and, since toque is proportional to the product of the values of the currents in the coils, it is proportional to the product of the current I vottage E. lie scale may, therefore, be graduated directly in watts. See Figure 47-1. The fixed current coil A si in series with the load, and the movable voltage coil V is across load. The resulting deflection is directly proportional to the active power delivered to the load.
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This note was uploaded on 02/22/2010 for the course EEE 360 taught by Professor Gorur during the Spring '08 term at University of Arizona- Tucson.

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exp%2047 wk5 - Experiment 47 Three-Phase Power Measurement...

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