Help, calculating motor power

P=VI, isn’t it that formula?

P=√3 UI cos∅

The formula for calculating the power of a three-phase motor is P=1.732*U*I*COSΦ; from this, the formula for calculating current is I=P/1.732/U/cosΦ. This relationship holds only in a delta connection, and it is precisely because of this delta connection that such trigonometric calculations are applicable. There are three types of power: active power P, reactive power Q, and apparent power S. The cosine of the phase difference (Φ) between voltage and current is called the power factor, denoted by cosΦ. Numerically, the power factor is the ratio of active power to apparent power, that is, cosΦ = P/S. The three types of power and the power factor cosΦ are related within a right-angled power triangle: the two legs are the active power and reactive power, while the hypotenuse is the apparent power. Real power squared + Reactive power squared = Apparent power squared. In a three-phase load, these three types of power are always present at the same time: Apparent power S = 1.732UI, Active power P = 1.732UIcosΦ, Reactive power Q = 1.732UIsinΦ. The power factor is cosΦ = P/S, and sinΦ = Q/S

Since there are no flow meters or pressure gauges for monitoring the pump’s operating conditions, it can only be estimated based on power! I’m also a complete newbie when it comes to electricity, so I’m here to ask for advice! Thank you

P = (√3) * U * I * cosΦ – this is the power under a three-phase 380V voltage system. Sometimes I simplify it by using P = 3*220*I*cosΦ; the power calculated this way is basically similar to the value obtained from the first formula

P=1.732UIcosΦ

The motor nameplate indicates the mechanical power output at the shaft; it is also necessary to calculate the efficiency…… I forgot to mention that earlier. . .

This post was last edited by DAOMS on 2017-3-24 at 12:28. 1. Determine the shaft power based on the load characteristics and power requirements. 2. Calculate the motor power based on shaft power, efficiency, and power factor. 3. Generally, the shaft power is 1.1–1.3 times the power required by the load; the exact value depends on the characteristics of the load (such as constant torque or constant speed), with an efficiency factor of 0.95. I can’t remember the specifics; the original poster can check out the book “Electric Drive,” as it contains detailed calculation methods. What I learned on my own in the past has been almost forgotten due to the long passage of time