GE EPM 5200 - Manual (Page 6)

CHAPTER 1: AC POWER MEASUREMENT
2 EPM 5000 series Advanced Power Meters GE Multilin
Apparent Power (VA)
Real Power (W)
Reactive
Power
(VAR)
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:
3
E
3
E
3
E
E E E ac bc ab
cn bn an
= = = = =
B
A
C
N
A B
C
1) Delta
2) Wye
Figure 1.3: Three-Phase System: (1) Delta, (2) Wye