NEC EXPRESS800, Service Manual

Page: 36 / 78

3-8 Planning Your System Rack Configuration
Calculating Load and Determining UPS
On-Battery Run Time
When you have chosen your configuration, you can use Table 3-4 and Table 3-5
to determine the load on a single power source and how much run time your
configuration can expect from your UPS in the event your main AC service is
interrupted.
To calculate the load and your on-battery run time, perform the following steps:
1.
Determine the total load placed on each power source. The maximum load
you can place on a single power source is:
Source Maximum Load
UPS 3000VA (2250W)
PDU 2880VA
Table 3-4 provides Volt/Amp load values of system components and
provides space to include other options.
You can calculate Volt/Amps by multiplying a component’s voltage by its
current requirement.

Voltage * Amps = VA
Or if your component’s power requirement is expressed in watts, multiply its
wattage rating by 1.4.

Watts * 1.4 = VA