How do you calculate reactive and apparent powers for a three phase induction motor?

Calculation of reactive power

Reactive power (Q) can be calculated by the following formula 4:

Q = UIsin Φ

Among them:

U is the effective value of the voltage,

I is the effective value of the current,

sinΦ is the sine of the phase difference between voltage and current.

In three-phase induction motors, the unit of reactive power is usually watt (var), kilowatt (kvar) or megawatt (Mvar).

Calculation of apparent power

The apparent power (S) can be calculated by the following formula 4:

S=UI

Alternatively, for a three-phase system, the apparent power can also be expressed as 3:

S=1.732 x U wire x I wire

U-wire is the line voltage,

Line I is line current.

The units of apparent power are usually volt-ampere (VA), kilovolt-ampere (kVA), or mega-volt-ampere (MVA).

Power factor

The power factor (cosΦ) is the ratio of the active power (P) consumed by the load to the apparent power (S), expressed as:

Φ= P/S

The power factor is a value between 0 and 1 that reflects the active power consumed by the load as a percentage of the apparent power.

Sum up

By the above formula, you can calculate the reactive power and apparent power of the three-phase induction motor. Note that these calculations assume that you already know the voltage, current, and phase difference of the system. If you need further help or specific examples, feel free to ask.