Watt Meter

Watt Meter

Watt Meters, or Wattmeters, measure single and three phase power usage (kW).
 
These units may also have data logging, memory of minimum and maximum values, memory hold and peak hold functions. They are primarily used for measurement of single phase and three phase Energy and Power. They can measure and display many of the following parameters using either a single or three phase wiring system.

• Apparent Power (kVA)
• Reactive Power (kVAR)
• Active Power (kWh)
• Power Factor
• Phase Angle
• True Power
• AC Current
• AC Voltage
• Frequency
• Harmonics
• Harmonic Distortion
• Phase Rotation

Here, a discussion of the Power Triangle follows:
There are three types of power -- true, reactive, and apparent -- relate to one another in what is referred to as the power triangle. The relationship between real power, reactive power and apparent power is shown below as vectors. P, Real power (true power, watts) is the horizontal vector and Q, reactive power (VAR) is the vertical vector. S, apparent power, (VA), is the hypotenuse of the right triangle below. The angle between the hypotenuse and the base of the triangle is Z, the impedance phase angle.