Uninterruptible runtime and/or redundancy increase. The battery strings

 

Uninterruptible
power systems (UPS’s) are often being referred to merely as a “batteries in a
box”. While in fact, they are very complex systems which perform numerous
functions. Those important functions ensure clean power and continuous uptime of
sensitive electronic facilities.

Nevertheless, performing
regular UPS maintenance is of crucial importance.
Without it, main UPS components will decay in time. To prevent that from happening we advise
you to schedule regular service visits, which must be done by trained and experienced experts. Performing
a regular service enhances your own knowledge about the power system. Understanding
how the main elements of your UPS function is of vital importance. This
knowledge enables you to more easily identify, and avoid, potential failures
and unwanted delays.

Allow us to introduce you
to four primary components of each UPS:

 

1.     Battery 

This main component can be compared to a “heart”
of UPS system. Essential battery function is to “kick in” when the system detects a loss of power from the primary
power source. The main purpose of batteries is to support the connected
load during a utility power failure. This component is the most critical UPS
component since it guarantees system reliability. Nevertheless, the battery can
be often considered as a part which doesn’t require inspection or maintenance. Such
a mistake can prove costly and can potentially cause a power failure.

The UPS can have many different configurations,
but each UPS must contain minimally one battery string. It is possible to add
multiple battery string which will result with runtime and/or redundancy increase.
The battery strings are serially connected, so if only one battery fails, the
whole battery string will fail.

Experience shows that up to 20% of UPS failures happen due to a bad battery. This fact
underlines the need and importance of regular inspection and maintenance.

The most commonly used batteries in UPS’s
are valve regulated lead acid (VRLA) batteries, including Gel
and AGM (Absorbed Glass Mat) batteries.

A VRLA battery works
on a basis of a pressure-relief valve system. That means that the negative
plate absorbs the oxygen which is normally produces on the positive plate. This
process prevents the creation of hydrogen on the negative plate. Instead of
hydrogen, the resulting product is water (H2O). In this way, the moisture is
retained within the battery. This type of battery never needs watering, and
they should never be opened as this would expose them to excess oxygen from the
air. In addition to damaging the batteries, opening also voids the warranty.

AGM batteries
(Absorbed Glass Mat)

This type of
batteries completely absorb electrolyte in separators. Separators are made of matted
glass fibers. Significant advantage of this type of batteries is that they are spill
proof. The AGM separators are wound around the positive plate and protect it
from the vibration damage. The battery strings and their components have a very
durable and compact housing. If regularly serviced and used in correct
application AGM batteries can have two
times longer life expectancy than the conventional batteries.

Gel (Gelled
Electrolyte) batteries

Most of the traditional
batteries contain electrolyte in liquid form. Instead, gel batteries contain
electrolyte a gelled state. Because there is no electrolyte in a liquid state, this
type of battery will not leak if tipped on its side. Noteworthy advantage of gel
batteries is increased resistance to significant discharge. This type of
batteries can have two or even three
times longer life expectancy, compared to regular AGM battery.

 

2.     Rectifier 

First important role of a rectifier in UPS is
to charge the batteries. His second function is to convert power from AC to DC.
In
case of a power surge, the system recognizes power loss and excludes rectifier from
the power circuit. Even in that case, power stays unchanged and utility is
being powered on batteries. After the utility main power is restored, the
rectifier starts to charge the batteries. At first, charging process is being
slowed down, to prevent overheating the batteries. Our Company uses a refined charging approach
which, which greatly slows the decay process.

 

3.     Inverter 

The UPS inverter receives the DC from the
DC buss. In case of a power surge,
the rectifier stops providing current to the DC buss, in which case the
batteries become main power source. During the power surge, inverter receives power
from
the batteries and maintains to run. After power restoration, the inverter
continues to receive DC from the rectifier. As long as inverter receives
power from any source, he newer stops to run.

 

4.     Static bypass 

Almost
all of the UPS’s contain a static bypass. His role is very important and we can
refer to it as a last line of defense. His function prevents loose of power in
case the inverter fails. In that case, static bypass switches the load directly
to the mains input feed. This way, the power circuit is being closed and the incoming power can be transferred to
the batteries, rectifier and the rest of the system. Main advantage of this
important component is that it allows functioning of the critical systems, even
in case of internal UPS components failure. Almost always, a
static bypass is an internal UPS part, but can also contain external switch.

 

Getting familiar with your
UPS and its primary components is important. When you understand main functions
and identify the critical components, you are able to act preventatively and assure optimal performance of your
system. Our recommendation is to plan minimally two maintenances each year. Such services should
incorporate an overall range of critical components inspections, in order to ensure
the good condition of your UPS.

Author: