GE EPM 5200 Three-Phase System, 2 Relationship between apparent, real and reactive power, 3 3

CHAPTER 1: AC POWER MEASUREMENT

Apparent Power (VA)	Reactive
	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: Three-Phase System

A three-phase system delivers higher levels of power for industrial and commercial applications; the three phases correspond to three potential lines. A 120° phase shift exists between the three potential lines.

A typical configuration has either a Delta connection or a Wye connection (see Figure 1.3, below).

In a three-phase system, the voltage levels between the phases and the neutral are uniform and defined by:

Ean = Ebn = Ecn = Eab = Ebc = Eac

3 3 3

A

C

A

1) Delta

B

B

2) Wye

N

C

Figure 1.3: Three-Phase System: (1) Delta, (2) Wye

2 EPM 5000 series Advanced Power Meters GE Multilin