How
long can equipment on a UPS keep
running after the power goes off
?
It
depends on how big a UPS do you
have and what kind of equipment
it protects? For most typical computer
workstations, one might have a UPS
that was rated to keep the machine
alive through a 15 minute power
loss. If you need a machine to survive
hours without power, you should
probably look at a more robust power
backup solution. Even if a UPS has
a very small load, it must still
operate it's DC (battery) to AC
converter, which costs power.
What
are the problems usually happen
to the power supply ?
Blackout,
power slump, power surge, continuous
under voltage, continuous over voltage,
frequency fluctuation, interference
of computers, switching transient,
harmonic distortion, etc.
How
are the "sizes" of UPS's determined
?
Typically,
a UPS has a VA rating. The VA rating
is the maximum number of Volts *
Amps it can deliver. The VA rating
is not the same as the power drain
(in Watts) of the equipment. Computers
are non linear load (non-resistive).
A typical PF (power factor: Watts/VA)
for workstations may be as low as
0.6, which means that if you record
a drain of 100 Watts, you need a
UPS with a VA rating of 167. Some
literature suggests that 0.7 may
be a good conversion factor, but
this will depend heavily on the
machine.
The
definition of UPS ?
An
Uninterruptible Power Supply is
a device that sits between a power
supply and your computer and other
valuable electronic equipment to
prevent undesired features of the
power source from adversely affecting
the performance of your devices.
Those undesired features include
blackouts, power sags and power
surges, etc. Your equipment can
maintain optimum performance and
lifetime with UPS protection.
UPS can provide
continuous, optimal power supplying
in the event of a power down instead
of utility line. The power supply
can resume within 4 to 8 milliseconds,
or even 0 milliseconds, which depends
on different types.
