APC AP9606 Specifications download pdf (Page 11)

Chapter 2. APC hardware and software background 3

Chapter 2. APC hardware and software background

In the following chapters, we describe some UPS units that are important for

cluster solutions. All described UPS units are by American Power Conversion

(APC). You can also get the Smart UPS units as an IBM option.

For a correct sizing of the UPS capacity you need some background information

on power.

They are different power types in alternate current (AC):

• Real power

• Blind or reactive power

• Apparent power

Real power is the actual power dissipated by the load and is calculated as

follows:

Where:

P Real power

U RMS voltage

I RMS current

ϕ Phase angle (phi) between the current and voltage

However, with a purely resistive load, there is no phase shift between current and

voltage, hence cos(

ϕ)=1.

Blind power, or reactive power, is the power that swings between generator and

load without any work in the load.

Blind power comes into coexistence if there is a phase shift between current and

voltage.

Apparent power is the quadratic sum of real and blind power:

PUI ϕcos⋅⋅=

PUI⋅=

QUI ϕ

sin⋅⋅=

Q+

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APC AP9606 Specifications Page 11