GE EPM 5350, EPM 5200, EPM 5300 instruction manual = E I cosΘ, Power W in a single phase system is

SINGLE PHASE SYSTEM CHAPTER 1: AC POWER MEASUREMENT

The power (W) in a single phase system is:

W = E • I • cosΘ

E = potential, I = current, and cosΘ = phase difference between the potential and the current.

Power in a 120/240V AC system is:

W = (ELine 1 • ILine 1 • cosΘ) + (ELine 2 • ILine 2 • cosΘ)

Phase differential between the potential and the current results from a non-resistive load, either reactive or capacitive.

Reactive power (VAR): The additional power consumed that does not produce any work

but must be delivered to the load: .

VAR = E ⋅ I ⋅ sinΘ

This is a measure of the inefficiency of the electrical system.

Apparent power (VA): The total power delivered to the load, and the vector sum of real power and reactive power.

Power Factor (PF): The ratio between real power and apparent power:

Reactive

Apparent Power (VA)Power

(VAR)

Real Power (W)

FIGURE 1–2:Relationship between apparent, real and reactive power

Ideal power distribution should have a PF of 1. This condition can be met only if no reactive power loads exist. In real life applications, many loads are inductive loads. Often, corrective capacitors are installed to correct Poor Power Factor (see Section 1.3).

1–2 EPM 5300 SERIES ADVANCED POWER METERS – INSTRUCTION MANUAL