Why is apparent power measured

However, reactive circuits actually store or return power. The reactive components cause a phase shift up to 90 degrees between the voltage and current waveforms which reduces the overlap between the two curves and effectively delivers less power to the loads. This phenomenon is represented by three different power measurements: reactive power , apparent power, and real power.

These three power measurements have a phase relationship that can be visualized in the power triangle, shown below. Apparent power is the combination of reactive power and real power, without reference to a phase angle.

Often, the decay will be an exponential damped ringing waveform, with a frequency of approximately kHz. They are caused by arcing faults, such as bad brushes in motors, and are rapidly damped out by even a few meters of distribution wiring.

Chipkin has Modbus solutions for almost every situation. Contact Us. Search Keyword:. The value of current and voltage keeps changing.

Which value do you use? The voltage and the current may not be in phase. Multiplying the current and the voltage when they are not in phase requires and adjustment to compensate for the phase. It is this phase shift that forces us to define Real, Apparent and Reactive Power.

Most loads are either inductive motors or resistive heaters and therefore the phase shift is typically in one direction. A motor has a winding. A wound conductor essentially defines an inductor.

Thus the winding presents the resistance of the wound wire and the inductance resulting from the winding. RMS or Effective Value Peak values in the alternating voltage or current curves only lasts a short instant. Apparent Power Apparent Power is the power delivered by a power source to a load like a motor. Did you know that we also do Modbus Integration Solutions? Need a Modbus Integration Solution?

The reason for this is that while the apparent power may be greater than the true power being consumed, the current flowing through the load is very real. For example, a reactive load across a VAC source may have a true power rating of 2, W, but an apparent power rating of 3, VA. The load current in this case would be 30 A, and not only would the AC source need to provide 30 A, wire sizes and circuit protection devices would need to be chosen to handle this current.

Power Factor. Power factor is the ratio unitless of true power measured in watts to apparent power measured in volt-amperes. Power factor can range from 0 for a purely reactive load to 1 for a purely resistive load.

When the load is purely resistive, the power factor is 1, and the true power equals apparent power. When a load is reactive, the power factor will be less than 1, and the true power will be less than the apparent power.