Total power measured using two-wattmeter or per-phase methods.
Total power in a balanced load is 3V_phI_phcosφ. The two-wattmeter method uses P=W₁+W₂ for three-wire systems and gives power factor from W₁/W₂. Energy meters in practice use digital sampling.
W₁=3 kW and W₂=1 kW gives P=4 kW.
Three-phase power measurement must be done correctly for billing and diagnosis, and the method depends on whether the system is balanced.
Total power measured using two-wattmeter or per-phase methods.
Three-phase power measurement must be done correctly for billing and diagnosis, and the method depends on whether the system is balanced.
In a three-wire system, the sum of two properly connected wattmeter readings gives the total power, even if the load is unbalanced.
Yes. Total power equals the square root of three times the line voltage times the line current times the power factor.
Typical applications include measuring the power of a three-phase motor during commissioning, checking the energy use of an industrial feeder for a billing audit and diagnosing an imbalance in a three-phase load using per-phase readings.
Study "Star and delta connections" first (topic 54 of 106 in Electrical Engineering). It covers the groundwork this topic builds on.
Blondel's theorem. Reverse reading indicates PF<0.5. Unbalance needs three meters.
W₁=3 kW and W₂=1 kW gives P=4 kW.
The next topic is "Electromagnetic induction in machines", which builds directly on this one.
It is classed as Intermediate in Electrical Engineering (topic 55 of 106). It is an intermediate topic. Work through the beginner topics in Electrical Engineering first.
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