Eaton Power Xpert PXM 4000, Руководство пользователя и инструкция по установке

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1 Introduction
Where the phase difference between the Current and the Potential is the result of a non-resistive
load, which can be either capacitive or reactive.
Reactive Power (VAR) is defined as any additional power consumed by the load that doesn’t do
any actual work. You can think of this as a measure of the inefficiency of the system. VAR is calcu -
lated as:
Apparent Power (VA) is defined as the total power that’s delivered to the load. It’s the vector sum
of the Power (W) and the Reactive Power (VAR).
Power Factor (PF) is the ratio between Power (W) and the Apparent Power (VA). Ideally, the power
factor should be 1; however, this can only occur if there are no inductive loads. In actuality, many
loads are inductive and capacitors are installed to correct a poor Power Factor. Power Factor (PF)
is calculated as:
THREE-PHASE
Three-phase is typically used for power transmission, but is also often used to power motors and
other industrial or commercial equipment. In three-phase systems, three conductors carry three
alternating currents of the same frequency. One conductor is the reference and the remaining con-
ductors have their currents delayed by one-third and two-thirds of a cycle.
Three-Phase Current
Phase A
Phase C
Phase B
Typically, three-phase systems use either a Delta connection or a Wye conncetion, as shown in the
following figure:
Typical Three-Phase Systems
B
A
C
A
N
B C
4-Wire “Wye” 3-Wire “Delta”