How to calculate three phase power

Three-phase circuit represents the main type of circuits that are actively used today in the production of electric energy, its transmission and distribution. This is a special case of a symmetrical polyphase network. But to correctly construct three-phase circuit, we first need to calculate its capacity, and other parameters.

You will need

• - personal computer with access to a global network;
• - source data.

Instruction

1. Set search string of the browser request "formulas to calculate power of three-phase circuit". In the proposed list of answers, select the in detail guide to perform calculations.
2. Calculate active power three-phase network. Remember that under the condition of unbalanced load active power three-phase circuit is equal to the sum of active powers of individual phases. That is, P = Pa + Pb + Pc. The formula for calculating the capacity of the individual phase is: P = UIcos φ, where U is phase voltage; I – current; φ is the phase angle between voltage and current. Substitute the original data and calculate the active power of separate phases, and then sum up the obtained results.
3. Calculate the reactive power three-phase network. This value is equal to the sum of reactive powers of individual phases. In other words, Q = Qa + Qb + Qc. For calculating reactive power of each phase use the following formula: Q = UIc sin φ, where the value of U - the value of the phase voltage; I – current; φ is the phase angle between voltage and current. Substitute in the formula the original data. Once you learn the reactive power of each phase, find the sum of the results obtained.
4. Calculate the full power three-phase network. Full power individual phase is given by: S = UI, where U - phase voltage and I is current.
5. Hoping the power of three-phase network, remember that for a symmetrical system voltage indicator phase voltage on each phase equal. Moreover, when a symmetrical load current at three different sections is equal, and the same angle of phase shift between voltage and current current. Therefore, the active power can be determined by the formula: P = cos φ 3UФ F. To calculate the reactive power use the formula: Q = 3 IF cos φ F. A calculation of full capacity perform, according to the formula: S = 3 IF F.