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20160308 Daily Question: Regarding electrical instrumentation knowledge – how is the power of a motor calculated, and how are useful work and useless work taken into account? Additionally, how is the mechanical efficiency determined?
p = w ÷ t. The useful work done is equal to G × H; the total work done is equal to the total work minus the useful work. Mechanical efficiency is the ratio of the useful work to the total work. η = Useful Work / Total Work. The useful work done by a heat engine refers to the work done on the machinery as a result of the energy generated by the combustion of fuel
The actual power consumption refers to the active power, and the calculation formula is P=1.732×U×I×cosφ. P is power, U is the voltage at the motor terminals, I is the operating current, and cosφ is the power factor indicated on the motor’s nameplate. Power multiplied by time equals energy consumption. Reactive power is not included in the electricity measurement; the formula involves replacing cosφ with sinφ. The sum of the squares of sinφ and cosφ equals 1, and using this value, sinφ can be calculated.
In AC circuits, when the phase angle between voltage and current is zero degrees, the current does work on the load; this is known as useful power. When the phase angle between voltage and current is ninety degrees, the current does no work on the load; this is known as useless power.
The actual power consumption refers to the active power, and the calculation formula is P=1.732×U×I×cosφ. P is power, U is the voltage at the motor terminals, I is the operating current, and cosφ is the power factor indicated on the motor’s nameplate. Power multiplied by time equals energy consumption. Reactive power is not included in the electricity measurement; the formula involves replacing cosφ with sinφ. The sum of the squares of sinφ and cosφ equals 1, and using this value, sinφ can be calculated.
Even though I passed, I still need to keep learning*